From 3cf708e179dfc81956d75cd919733c2cdf2160ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 8 Aug 2024 17:58:20 +0200
Subject: [PATCH 01/11] Fixed types of properties of contextual filtering
 mapped types (#56201)

---
 src/compiler/checker.ts                       |   2 +-
 ...opertyOfGenericFilteringMappedType.symbols |  90 +++++++++++++
 ...PropertyOfGenericFilteringMappedType.types | 127 ++++++++++++++++++
 ...ualPropertyOfGenericFilteringMappedType.ts |  33 +++++
 4 files changed, 251 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.symbols
 create mode 100644 tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.types
 create mode 100644 tests/cases/compiler/contextualPropertyOfGenericFilteringMappedType.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 06346c66ba0ac..4cdd0531b1c04 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -31620,7 +31620,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function getTypeOfPropertyOfContextualType(type: Type, name: __String, nameType?: Type) {
         return mapType(type, t => {
-            if (isGenericMappedType(t) && !t.declaration.nameType) {
+            if (isGenericMappedType(t) && getMappedTypeNameTypeKind(t) !== MappedTypeNameTypeKind.Remapping) {
                 const constraint = getConstraintTypeFromMappedType(t);
                 const constraintOfConstraint = getBaseConstraintOfType(constraint) || constraint;
                 const propertyNameType = nameType || getStringLiteralType(unescapeLeadingUnderscores(name));
diff --git a/tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.symbols b/tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.symbols
new file mode 100644
index 0000000000000..5bcaba07ec255
--- /dev/null
+++ b/tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.symbols
@@ -0,0 +1,90 @@
+//// [tests/cases/compiler/contextualPropertyOfGenericFilteringMappedType.ts] ////
+
+=== contextualPropertyOfGenericFilteringMappedType.ts ===
+declare function f1<T extends object>(
+>f1 : Symbol(f1, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 0, 0))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 0, 20))
+
+  data: T,
+>data : Symbol(data, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 0, 38))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 0, 20))
+
+  handlers: { [P in keyof T as P]: (value: T[P], prop: P) => void },
+>handlers : Symbol(handlers, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 1, 10))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 2, 15))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 0, 20))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 2, 15))
+>value : Symbol(value, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 2, 36))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 0, 20))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 2, 15))
+>prop : Symbol(prop, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 2, 48))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 2, 15))
+
+): void;
+
+f1(
+>f1 : Symbol(f1, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 0, 0))
+  {
+    foo: 0,
+>foo : Symbol(foo, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 6, 3))
+
+    bar: "",
+>bar : Symbol(bar, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 7, 11))
+
+  },
+  {
+    foo: (value, key) => {},
+>foo : Symbol(foo, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 10, 3))
+>value : Symbol(value, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 11, 10))
+>key : Symbol(key, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 11, 16))
+
+    bar: (value, key) => {},
+>bar : Symbol(bar, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 11, 28))
+>value : Symbol(value, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 12, 10))
+>key : Symbol(key, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 12, 16))
+
+  },
+);
+
+declare function f2<T extends object>(
+>f2 : Symbol(f2, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 14, 2))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 16, 20))
+
+  data: T,
+>data : Symbol(data, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 16, 38))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 16, 20))
+
+  handlers: { [P in keyof T as T[P] extends string ? P : never]: (value: T[P], prop: P) => void },
+>handlers : Symbol(handlers, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 17, 10))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 18, 15))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 16, 20))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 16, 20))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 18, 15))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 18, 15))
+>value : Symbol(value, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 18, 66))
+>T : Symbol(T, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 16, 20))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 18, 15))
+>prop : Symbol(prop, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 18, 78))
+>P : Symbol(P, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 18, 15))
+
+): void;
+
+f2(
+>f2 : Symbol(f2, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 14, 2))
+  {
+    foo: 0,
+>foo : Symbol(foo, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 22, 3))
+
+    bar: "",
+>bar : Symbol(bar, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 23, 11))
+
+  },
+  {
+    bar: (value, key) => {},
+>bar : Symbol(bar, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 26, 3))
+>value : Symbol(value, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 27, 10))
+>key : Symbol(key, Decl(contextualPropertyOfGenericFilteringMappedType.ts, 27, 16))
+
+  },
+);
+
diff --git a/tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.types b/tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.types
new file mode 100644
index 0000000000000..b55c98f6f650f
--- /dev/null
+++ b/tests/baselines/reference/contextualPropertyOfGenericFilteringMappedType.types
@@ -0,0 +1,127 @@
+//// [tests/cases/compiler/contextualPropertyOfGenericFilteringMappedType.ts] ////
+
+=== contextualPropertyOfGenericFilteringMappedType.ts ===
+declare function f1<T extends object>(
+>f1 : <T extends object>(data: T, handlers: { [P in keyof T as P]: (value: T[P], prop: P) => void; }) => void
+>   : ^ ^^^^^^^^^      ^^    ^^ ^^        ^^                                                        ^^^^^    
+
+  data: T,
+>data : T
+>     : ^
+
+  handlers: { [P in keyof T as P]: (value: T[P], prop: P) => void },
+>handlers : { [P in keyof T as P]: (value: T[P], prop: P) => void; }
+>         : ^^^ ^^^^^^^^^^^^^^^^^^^^     ^^    ^^    ^^ ^^^^^    ^^^
+>value : T[P]
+>      : ^^^^
+>prop : P
+>     : ^
+
+): void;
+
+f1(
+>f1(  {    foo: 0,    bar: "",  },  {    foo: (value, key) => {},    bar: (value, key) => {},  },) : void
+>                                                                                                  : ^^^^
+>f1 : <T extends object>(data: T, handlers: { [P in keyof T as P]: (value: T[P], prop: P) => void; }) => void
+>   : ^ ^^^^^^^^^      ^^    ^^ ^^        ^^                                                        ^^^^^    
+  {
+>{    foo: 0,    bar: "",  } : { foo: number; bar: string; }
+>                            : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+    foo: 0,
+>foo : number
+>    : ^^^^^^
+>0 : 0
+>  : ^
+
+    bar: "",
+>bar : string
+>    : ^^^^^^
+>"" : ""
+>   : ^^
+
+  },
+  {
+>{    foo: (value, key) => {},    bar: (value, key) => {},  } : { foo: (value: number, key: "foo") => void; bar: (value: string, key: "bar") => void; }
+>                                                             : ^^^^^^^^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^^^^^^^^^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^^^^
+
+    foo: (value, key) => {},
+>foo : (value: number, key: "foo") => void
+>    : ^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^
+>(value, key) => {} : (value: number, key: "foo") => void
+>                   : ^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^
+>value : number
+>      : ^^^^^^
+>key : "foo"
+>    : ^^^^^
+
+    bar: (value, key) => {},
+>bar : (value: string, key: "bar") => void
+>    : ^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^
+>(value, key) => {} : (value: string, key: "bar") => void
+>                   : ^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^
+>value : string
+>      : ^^^^^^
+>key : "bar"
+>    : ^^^^^
+
+  },
+);
+
+declare function f2<T extends object>(
+>f2 : <T extends object>(data: T, handlers: { [P in keyof T as T[P] extends string ? P : never]: (value: T[P], prop: P) => void; }) => void
+>   : ^ ^^^^^^^^^      ^^    ^^ ^^        ^^                                                                                      ^^^^^    
+
+  data: T,
+>data : T
+>     : ^
+
+  handlers: { [P in keyof T as T[P] extends string ? P : never]: (value: T[P], prop: P) => void },
+>handlers : { [P in keyof T as T[P] extends string ? P : never]: (value: T[P], prop: P) => void; }
+>         : ^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^     ^^    ^^    ^^ ^^^^^    ^^^
+>value : T[P]
+>      : ^^^^
+>prop : P
+>     : ^
+
+): void;
+
+f2(
+>f2(  {    foo: 0,    bar: "",  },  {    bar: (value, key) => {},  },) : void
+>                                                                      : ^^^^
+>f2 : <T extends object>(data: T, handlers: { [P in keyof T as T[P] extends string ? P : never]: (value: T[P], prop: P) => void; }) => void
+>   : ^ ^^^^^^^^^      ^^    ^^ ^^        ^^                                                                                      ^^^^^    
+  {
+>{    foo: 0,    bar: "",  } : { foo: number; bar: string; }
+>                            : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+    foo: 0,
+>foo : number
+>    : ^^^^^^
+>0 : 0
+>  : ^
+
+    bar: "",
+>bar : string
+>    : ^^^^^^
+>"" : ""
+>   : ^^
+
+  },
+  {
+>{    bar: (value, key) => {},  } : { bar: (value: string, key: "bar") => void; }
+>                                 : ^^^^^^^^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^^^^
+
+    bar: (value, key) => {},
+>bar : (value: string, key: "bar") => void
+>    : ^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^
+>(value, key) => {} : (value: string, key: "bar") => void
+>                   : ^     ^^^^^^^^^^   ^^^^^^^^^^^^^^^^
+>value : string
+>      : ^^^^^^
+>key : "bar"
+>    : ^^^^^
+
+  },
+);
+
diff --git a/tests/cases/compiler/contextualPropertyOfGenericFilteringMappedType.ts b/tests/cases/compiler/contextualPropertyOfGenericFilteringMappedType.ts
new file mode 100644
index 0000000000000..824a6d554344c
--- /dev/null
+++ b/tests/cases/compiler/contextualPropertyOfGenericFilteringMappedType.ts
@@ -0,0 +1,33 @@
+// @strict: true
+// @noEmit: true
+
+declare function f1<T extends object>(
+  data: T,
+  handlers: { [P in keyof T as P]: (value: T[P], prop: P) => void },
+): void;
+
+f1(
+  {
+    foo: 0,
+    bar: "",
+  },
+  {
+    foo: (value, key) => {},
+    bar: (value, key) => {},
+  },
+);
+
+declare function f2<T extends object>(
+  data: T,
+  handlers: { [P in keyof T as T[P] extends string ? P : never]: (value: T[P], prop: P) => void },
+): void;
+
+f2(
+  {
+    foo: 0,
+    bar: "",
+  },
+  {
+    bar: (value, key) => {},
+  },
+);

From 67d0fc13cedbcbe47029270ffcfba2c9dbdc9a96 Mon Sep 17 00:00:00 2001
From: Ron Buckton <ron.buckton@microsoft.com>
Date: Thu, 8 Aug 2024 12:20:59 -0400
Subject: [PATCH 02/11] Use global `Iterator.prototype` for down-level
 generators (#59514)

---
 src/compiler/factory/emitHelpers.ts           |  6 +--
 .../unittests/evaluation/asyncGenerator.ts    | 22 ++++++++
 .../unittests/evaluation/generator.ts         | 22 ++++++++
 .../reference/asyncArrowFunction11_es5.js     |  4 +-
 .../asyncAwaitIsolatedModules_es5.js          |  4 +-
 tests/baselines/reference/asyncAwait_es5.js   |  4 +-
 .../reference/asyncFunctionNoReturnType.js    |  4 +-
 ...asyncFunctionReturnExpressionErrorSpans.js |  4 +-
 .../asyncFunctionTempVariableScoping.js       |  4 +-
 ...ncFunctionWithForStatementNoInitializer.js |  4 +-
 .../reference/asyncImportNestedYield.js       |  6 +--
 .../reference/asyncImportedPromise_es5.js     |  4 +-
 .../baselines/reference/asyncMultiFile_es5.js |  4 +-
 ...awaitUsingDeclarations.1(target=es2015).js |  2 +-
 ...awaitUsingDeclarations.1(target=es2017).js |  2 +-
 .../awaitUsingDeclarations.1(target=es5).js   |  6 +--
 .../awaitUsingDeclarations.2(target=es5).js   |  4 +-
 .../awaitUsingDeclarations.3(target=es5).js   |  4 +-
 ...awaitUsingDeclarationsInFor(target=es5).js |  4 +-
 ...ingDeclarationsInForAwaitOf(target=es5).js |  4 +-
 ...gDeclarationsInForAwaitOf.3(target=es5).js |  4 +-
 ...tUsingDeclarationsInForOf.1(target=es5).js |  4 +-
 ...tUsingDeclarationsInForOf.5(target=es5).js |  4 +-
 ...blockScopedBindingsInDownlevelGenerator.js |  4 +-
 .../blockScopedVariablesUseBeforeDef.js       |  6 +--
 tests/baselines/reference/castOfYield.js      |  4 +-
 .../checkJsxSubtleSkipContextSensitiveBug.js  |  4 +-
 .../baselines/reference/classStaticBlock6.js  |  4 +-
 .../baselines/reference/classStaticBlock7.js  |  4 +-
 .../reference/contextualReturnTypeOfIIFE.js   |  4 +-
 .../controlFlowForCatchAndFinally.js          |  4 +-
 .../reference/correctOrderOfPromiseMethod.js  |  4 +-
 .../reference/declarationEmitPrivateAsync.js  |  4 +-
 .../dependentDestructuredVariables.js         |  2 +-
 .../destructureOfVariableSameAsShorthand.js   |  4 +-
 .../destructuringControlFlowNoCrash.js        |  4 +-
 ...tElaborateAssignabilityToTypeParameters.js |  4 +-
 ...ter.asyncGenerators.classMethods.es2015.js | 18 +++----
 ...mitter.asyncGenerators.classMethods.es5.js | 54 +++++++++----------
 ...cGenerators.functionDeclarations.es2015.js | 14 ++---
 ...syncGenerators.functionDeclarations.es5.js | 42 +++++++--------
 ...ncGenerators.functionExpressions.es2015.js | 14 ++---
 ...asyncGenerators.functionExpressions.es5.js | 42 +++++++--------
 ...cGenerators.objectLiteralMethods.es2015.js | 14 ++---
 ...syncGenerators.objectLiteralMethods.es5.js | 42 +++++++--------
 .../emitter.forAwait(target=es2015).js        |  8 +--
 .../emitter.forAwait(target=es2017).js        |  8 +--
 .../reference/emitter.forAwait(target=es5).js | 36 ++++++-------
 .../baselines/reference/es5-asyncFunction.js  |  4 +-
 .../es5-asyncFunctionLongObjectLiteral.js     |  4 +-
 .../es5-importHelpersAsyncFunctions.js        |  4 +-
 .../exportDefaultFunctionInNamespace.js       |  4 +-
 ...essionsForbiddenInParameterInitializers.js |  4 +-
 .../forAwaitPerIterationBindingDownlevel.js   |  6 +--
 .../baselines/reference/importAttributes7.js  |  4 +-
 .../importCallExpressionAsyncES5AMD.js        |  4 +-
 .../importCallExpressionAsyncES5CJS.js        |  4 +-
 .../importCallExpressionAsyncES5System.js     |  4 +-
 .../importCallExpressionAsyncES5UMD.js        |  4 +-
 .../importCallExpressionNestedAMD2.js         |  4 +-
 .../importCallExpressionNestedCJS2.js         |  4 +-
 .../importCallExpressionNestedES20152.js      |  4 +-
 .../importCallExpressionNestedES20202.js      |  4 +-
 .../importCallExpressionNestedSystem2.js      |  4 +-
 .../importCallExpressionNestedUMD2.js         |  4 +-
 ...portCallExpressionNoModuleKindSpecified.js |  4 +-
 .../importMeta(module=commonjs,target=es5).js |  4 +-
 .../importMeta(module=es2020,target=es5).js   |  4 +-
 .../importMeta(module=esnext,target=es5).js   |  4 +-
 .../importMeta(module=system,target=es5).js   |  4 +-
 .../invalidContinueInDownlevelAsync.js        |  4 +-
 .../jsFileCompilationAwaitModifier.js         |  4 +-
 tests/baselines/reference/jsxElementType.js   |  4 +-
 .../reference/labeledStatementWithLabel.js    |  4 +-
 ...lesExportsSpecifierGenerationConditions.js |  4 +-
 .../neverAsDiscriminantType(strict=false).js  |  4 +-
 .../neverAsDiscriminantType(strict=true).js   |  4 +-
 tests/baselines/reference/objectRestSpread.js |  2 +-
 .../operationsAvailableOnPromisedType.js      |  4 +-
 .../parenthesizedAsyncArrowFunction.js        |  4 +-
 .../privateNamesIncompatibleModifiers.js      |  2 +-
 .../reference/promiseDefinitionTest.js        |  4 +-
 ...uxLikeDeferredInferenceAllowsAssignment.js |  4 +-
 ...fParamsFromGeneratorMakesRequiredParams.js |  4 +-
 .../templateStringWithEmbeddedYieldKeyword.js |  4 +-
 .../transformNestedGeneratorsWithTry.js       |  4 +-
 .../usingDeclarations.1(target=es2015).js     |  2 +-
 .../usingDeclarations.1(target=es2017).js     |  2 +-
 .../usingDeclarations.1(target=es5).js        |  6 +--
 ...ingDeclarationsInForAwaitOf(target=es5).js |  4 +-
 .../yieldInForInInDownlevelGenerator.js       |  4 +-
 91 files changed, 345 insertions(+), 301 deletions(-)

diff --git a/src/compiler/factory/emitHelpers.ts b/src/compiler/factory/emitHelpers.ts
index 3b3dc97ddb43f..8cc453299e3f8 100644
--- a/src/compiler/factory/emitHelpers.ts
+++ b/src/compiler/factory/emitHelpers.ts
@@ -836,7 +836,7 @@ const asyncGeneratorHelper: UnscopedEmitHelper = {
         var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
             if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
             var g = generator.apply(thisArg, _arguments || []), i, q = [];
-            return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+            return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
             function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
             function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
             function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -1102,8 +1102,8 @@ const generatorHelper: UnscopedEmitHelper = {
     priority: 6,
     text: `
             var __generator = (this && this.__generator) || function (thisArg, body) {
-                var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-                return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+                var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+                return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
                 function verb(n) { return function (v) { return step([n, v]); }; }
                 function step(op) {
                     if (f) throw new TypeError("Generator is already executing.");
diff --git a/src/testRunner/unittests/evaluation/asyncGenerator.ts b/src/testRunner/unittests/evaluation/asyncGenerator.ts
index 78c54bde9238e..bcfff9215b0db 100644
--- a/src/testRunner/unittests/evaluation/asyncGenerator.ts
+++ b/src/testRunner/unittests/evaluation/asyncGenerator.ts
@@ -83,4 +83,26 @@ describe("unittests:: evaluation:: asyncGeneratorEvaluation", () => {
             { done: true, value: 2 },
         ]);
     });
+    it("Supports global `AsyncIterator.prototype` if present", () => {
+        class AsyncIterator {}
+        const { gen } = evaluator.evaluateTypeScript(
+            `
+            export async function * gen() {}
+            `,
+            { target: ts.ScriptTarget.ES5 },
+            { AsyncIterator },
+        );
+        const g = gen();
+        assert.instanceOf(g, AsyncIterator);
+    });
+    it("Ignores global `AsyncIterator.prototype` if missing", () => {
+        const { gen } = evaluator.evaluateTypeScript(
+            `
+            export async function * gen() {}
+            `,
+            { target: ts.ScriptTarget.ES5 },
+            { AsyncIterator: undefined },
+        );
+        gen();
+    });
 });
diff --git a/src/testRunner/unittests/evaluation/generator.ts b/src/testRunner/unittests/evaluation/generator.ts
index 06f22c3680fa5..4b1e3a1ffd319 100644
--- a/src/testRunner/unittests/evaluation/generator.ts
+++ b/src/testRunner/unittests/evaluation/generator.ts
@@ -39,4 +39,26 @@ describe("unittests:: evaluation:: generatorEvaluation", () => {
         assert.deepEqual(g.next(), { value: undefined, done: true });
         assert.deepEqual(output, []);
     });
+    it("Supports global `Iterator.prototype` if present", () => {
+        class Iterator {}
+        const { gen } = evaluator.evaluateTypeScript(
+            `
+            export function * gen() {}
+            `,
+            { target: ts.ScriptTarget.ES5 },
+            { Iterator },
+        );
+        const g = gen();
+        assert.instanceOf(g, Iterator);
+    });
+    it("Ignores global `Iterator.prototype` if missing", () => {
+        const { gen } = evaluator.evaluateTypeScript(
+            `
+            export function * gen() {}
+            `,
+            { target: ts.ScriptTarget.ES5 },
+            { Iterator: undefined },
+        );
+        gen();
+    });
 });
diff --git a/tests/baselines/reference/asyncArrowFunction11_es5.js b/tests/baselines/reference/asyncArrowFunction11_es5.js
index 3f1f3491d7aca..932079f3c83f9 100644
--- a/tests/baselines/reference/asyncArrowFunction11_es5.js
+++ b/tests/baselines/reference/asyncArrowFunction11_es5.js
@@ -20,8 +20,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js b/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js
index 7c763f9ecf8ab..c5e0e7aaa34f5 100644
--- a/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js
+++ b/tests/baselines/reference/asyncAwaitIsolatedModules_es5.js
@@ -53,8 +53,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncAwait_es5.js b/tests/baselines/reference/asyncAwait_es5.js
index 2fd12346bb883..8bc581f48de17 100644
--- a/tests/baselines/reference/asyncAwait_es5.js
+++ b/tests/baselines/reference/asyncAwait_es5.js
@@ -59,8 +59,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncFunctionNoReturnType.js b/tests/baselines/reference/asyncFunctionNoReturnType.js
index fb4f9585cc2ae..ef0a529fcc5ad 100644
--- a/tests/baselines/reference/asyncFunctionNoReturnType.js
+++ b/tests/baselines/reference/asyncFunctionNoReturnType.js
@@ -18,8 +18,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncFunctionReturnExpressionErrorSpans.js b/tests/baselines/reference/asyncFunctionReturnExpressionErrorSpans.js
index 523416cff6a76..2863404726a47 100644
--- a/tests/baselines/reference/asyncFunctionReturnExpressionErrorSpans.js
+++ b/tests/baselines/reference/asyncFunctionReturnExpressionErrorSpans.js
@@ -34,8 +34,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncFunctionTempVariableScoping.js b/tests/baselines/reference/asyncFunctionTempVariableScoping.js
index 16b6afaf7a54d..a5a52a5c518b7 100644
--- a/tests/baselines/reference/asyncFunctionTempVariableScoping.js
+++ b/tests/baselines/reference/asyncFunctionTempVariableScoping.js
@@ -17,8 +17,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncFunctionWithForStatementNoInitializer.js b/tests/baselines/reference/asyncFunctionWithForStatementNoInitializer.js
index ddc852cb93a92..8ea440e35cad1 100644
--- a/tests/baselines/reference/asyncFunctionWithForStatementNoInitializer.js
+++ b/tests/baselines/reference/asyncFunctionWithForStatementNoInitializer.js
@@ -37,8 +37,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncImportNestedYield.js b/tests/baselines/reference/asyncImportNestedYield.js
index f7e42c3e3df25..a6251abe5203d 100644
--- a/tests/baselines/reference/asyncImportNestedYield.js
+++ b/tests/baselines/reference/asyncImportNestedYield.js
@@ -7,8 +7,8 @@ async function* foo() {
 
 //// [asyncImportNestedYield.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -37,7 +37,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/asyncImportedPromise_es5.js b/tests/baselines/reference/asyncImportedPromise_es5.js
index aaaf4a95491f8..c6841ddd8a6f1 100644
--- a/tests/baselines/reference/asyncImportedPromise_es5.js
+++ b/tests/baselines/reference/asyncImportedPromise_es5.js
@@ -48,8 +48,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/asyncMultiFile_es5.js b/tests/baselines/reference/asyncMultiFile_es5.js
index 2dd73b8b6c76e..e022b1e864a6b 100644
--- a/tests/baselines/reference/asyncMultiFile_es5.js
+++ b/tests/baselines/reference/asyncMultiFile_es5.js
@@ -16,8 +16,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/awaitUsingDeclarations.1(target=es2015).js b/tests/baselines/reference/awaitUsingDeclarations.1(target=es2015).js
index 60d690d76bda0..6468ced72c728 100644
--- a/tests/baselines/reference/awaitUsingDeclarations.1(target=es2015).js
+++ b/tests/baselines/reference/awaitUsingDeclarations.1(target=es2015).js
@@ -165,7 +165,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/awaitUsingDeclarations.1(target=es2017).js b/tests/baselines/reference/awaitUsingDeclarations.1(target=es2017).js
index 31b8b0bdf0b82..1277db5bcdd32 100644
--- a/tests/baselines/reference/awaitUsingDeclarations.1(target=es2017).js
+++ b/tests/baselines/reference/awaitUsingDeclarations.1(target=es2017).js
@@ -156,7 +156,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/awaitUsingDeclarations.1(target=es5).js b/tests/baselines/reference/awaitUsingDeclarations.1(target=es5).js
index a34ff4098232c..eb4005130a99b 100644
--- a/tests/baselines/reference/awaitUsingDeclarations.1(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarations.1(target=es5).js
@@ -110,8 +110,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -192,7 +192,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/awaitUsingDeclarations.2(target=es5).js b/tests/baselines/reference/awaitUsingDeclarations.2(target=es5).js
index 80fa7d99ba97b..7241ac59bb64e 100644
--- a/tests/baselines/reference/awaitUsingDeclarations.2(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarations.2(target=es5).js
@@ -19,8 +19,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/awaitUsingDeclarations.3(target=es5).js b/tests/baselines/reference/awaitUsingDeclarations.3(target=es5).js
index 57e87730665f5..c774b207cdb52 100644
--- a/tests/baselines/reference/awaitUsingDeclarations.3(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarations.3(target=es5).js
@@ -21,8 +21,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInFor(target=es5).js b/tests/baselines/reference/awaitUsingDeclarationsInFor(target=es5).js
index f01f673a98836..d8226409a5dac 100644
--- a/tests/baselines/reference/awaitUsingDeclarationsInFor(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarationsInFor(target=es5).js
@@ -20,8 +20,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es5).js b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es5).js
index 2e401a484063b..4deda344151fc 100644
--- a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf(target=es5).js
@@ -17,8 +17,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf.3(target=es5).js b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf.3(target=es5).js
index abe97e09c15d0..f929d3d0c6ced 100644
--- a/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf.3(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarationsInForAwaitOf.3(target=es5).js
@@ -24,8 +24,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es5).js b/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es5).js
index 3dab903ba3c89..b48951bbe6d5e 100644
--- a/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarationsInForOf.1(target=es5).js
@@ -18,8 +18,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/awaitUsingDeclarationsInForOf.5(target=es5).js b/tests/baselines/reference/awaitUsingDeclarationsInForOf.5(target=es5).js
index 1b0ea1fd6307e..6b9e8308d45a9 100644
--- a/tests/baselines/reference/awaitUsingDeclarationsInForOf.5(target=es5).js
+++ b/tests/baselines/reference/awaitUsingDeclarationsInForOf.5(target=es5).js
@@ -24,8 +24,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js b/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js
index fa6167ff384bf..ca74ec4d9ddb1 100644
--- a/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js
+++ b/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js
@@ -10,8 +10,8 @@ function* a() {
 
 //// [blockScopedBindingsInDownlevelGenerator.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/blockScopedVariablesUseBeforeDef.js b/tests/baselines/reference/blockScopedVariablesUseBeforeDef.js
index fa9bd38069f63..92f6719edaf89 100644
--- a/tests/baselines/reference/blockScopedVariablesUseBeforeDef.js
+++ b/tests/baselines/reference/blockScopedVariablesUseBeforeDef.js
@@ -164,8 +164,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -198,7 +198,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/castOfYield.js b/tests/baselines/reference/castOfYield.js
index 0392eb7e354fa..94de9e5dddfdd 100644
--- a/tests/baselines/reference/castOfYield.js
+++ b/tests/baselines/reference/castOfYield.js
@@ -10,8 +10,8 @@ function* f() {
 
 //// [castOfYield.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/checkJsxSubtleSkipContextSensitiveBug.js b/tests/baselines/reference/checkJsxSubtleSkipContextSensitiveBug.js
index 0393f492811df..2eca8424cd89c 100644
--- a/tests/baselines/reference/checkJsxSubtleSkipContextSensitiveBug.js
+++ b/tests/baselines/reference/checkJsxSubtleSkipContextSensitiveBug.js
@@ -53,8 +53,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/classStaticBlock6.js b/tests/baselines/reference/classStaticBlock6.js
index ff75c42c44a50..be445fb7d4969 100644
--- a/tests/baselines/reference/classStaticBlock6.js
+++ b/tests/baselines/reference/classStaticBlock6.js
@@ -91,8 +91,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/classStaticBlock7.js b/tests/baselines/reference/classStaticBlock7.js
index 238a20e14297d..29d74bf42609d 100644
--- a/tests/baselines/reference/classStaticBlock7.js
+++ b/tests/baselines/reference/classStaticBlock7.js
@@ -57,8 +57,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/contextualReturnTypeOfIIFE.js b/tests/baselines/reference/contextualReturnTypeOfIIFE.js
index 74b82182ceb1b..7baee9f0d4c96 100644
--- a/tests/baselines/reference/contextualReturnTypeOfIIFE.js
+++ b/tests/baselines/reference/contextualReturnTypeOfIIFE.js
@@ -25,8 +25,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/controlFlowForCatchAndFinally.js b/tests/baselines/reference/controlFlowForCatchAndFinally.js
index 949a178f7e413..65f0fe897cc92 100644
--- a/tests/baselines/reference/controlFlowForCatchAndFinally.js
+++ b/tests/baselines/reference/controlFlowForCatchAndFinally.js
@@ -54,8 +54,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/correctOrderOfPromiseMethod.js b/tests/baselines/reference/correctOrderOfPromiseMethod.js
index 900ffee4fb9cc..4ae573b834198 100644
--- a/tests/baselines/reference/correctOrderOfPromiseMethod.js
+++ b/tests/baselines/reference/correctOrderOfPromiseMethod.js
@@ -43,8 +43,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/declarationEmitPrivateAsync.js b/tests/baselines/reference/declarationEmitPrivateAsync.js
index 336c908724ff4..b3da5fed3f089 100644
--- a/tests/baselines/reference/declarationEmitPrivateAsync.js
+++ b/tests/baselines/reference/declarationEmitPrivateAsync.js
@@ -19,8 +19,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/dependentDestructuredVariables.js b/tests/baselines/reference/dependentDestructuredVariables.js
index 7d32808909bf7..a91ecf55ada98 100644
--- a/tests/baselines/reference/dependentDestructuredVariables.js
+++ b/tests/baselines/reference/dependentDestructuredVariables.js
@@ -482,7 +482,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/destructureOfVariableSameAsShorthand.js b/tests/baselines/reference/destructureOfVariableSameAsShorthand.js
index 26cf986a844e3..c8e0620ea8ae9 100644
--- a/tests/baselines/reference/destructureOfVariableSameAsShorthand.js
+++ b/tests/baselines/reference/destructureOfVariableSameAsShorthand.js
@@ -39,8 +39,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/destructuringControlFlowNoCrash.js b/tests/baselines/reference/destructuringControlFlowNoCrash.js
index 8335829ac4335..1cadd21894ac1 100644
--- a/tests/baselines/reference/destructuringControlFlowNoCrash.js
+++ b/tests/baselines/reference/destructuringControlFlowNoCrash.js
@@ -30,8 +30,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/doNotElaborateAssignabilityToTypeParameters.js b/tests/baselines/reference/doNotElaborateAssignabilityToTypeParameters.js
index 5d8d8ca8f4bb5..e0cc967c19563 100644
--- a/tests/baselines/reference/doNotElaborateAssignabilityToTypeParameters.js
+++ b/tests/baselines/reference/doNotElaborateAssignabilityToTypeParameters.js
@@ -25,8 +25,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/emitter.asyncGenerators.classMethods.es2015.js b/tests/baselines/reference/emitter.asyncGenerators.classMethods.es2015.js
index 5be6ad0fe3911..34333f4d0bc8e 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.classMethods.es2015.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.classMethods.es2015.js
@@ -65,7 +65,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -85,7 +85,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -106,7 +106,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -139,7 +139,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -160,7 +160,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -193,7 +193,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -214,7 +214,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -235,7 +235,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -258,7 +258,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js b/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js
index 9bbe5eb71297e..d39903e283504 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js
@@ -62,8 +62,8 @@ class C9 extends B9 {
 
 //// [C1.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -92,7 +92,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -115,8 +115,8 @@ var C1 = /** @class */ (function () {
 }());
 //// [C2.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -145,7 +145,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -175,8 +175,8 @@ var C2 = /** @class */ (function () {
 }());
 //// [C3.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -205,7 +205,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -235,8 +235,8 @@ var C3 = /** @class */ (function () {
 }());
 //// [C4.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -277,7 +277,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -318,8 +318,8 @@ var C4 = /** @class */ (function () {
 }());
 //// [C5.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -348,7 +348,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -409,8 +409,8 @@ var C5 = /** @class */ (function () {
 }());
 //// [C6.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -439,7 +439,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -468,8 +468,8 @@ var C6 = /** @class */ (function () {
 }());
 //// [C7.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -498,7 +498,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -524,8 +524,8 @@ var C7 = /** @class */ (function () {
 }());
 //// [C8.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -554,7 +554,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -595,8 +595,8 @@ var __extends = (this && this.__extends) || (function () {
     };
 })();
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -625,7 +625,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es2015.js b/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es2015.js
index bebb30336dbb2..2271510771807 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es2015.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es2015.js
@@ -34,7 +34,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -52,7 +52,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -71,7 +71,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -102,7 +102,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -121,7 +121,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -152,7 +152,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -171,7 +171,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js b/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js
index 04b4bc949ac78..a129d13003af0 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js
@@ -31,8 +31,8 @@ async function * f7() {
 
 //// [F1.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -61,7 +61,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -79,8 +79,8 @@ function f1() {
 }
 //// [F2.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -109,7 +109,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -134,8 +134,8 @@ function f2() {
 }
 //// [F3.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -164,7 +164,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -189,8 +189,8 @@ function f3() {
 }
 //// [F4.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -231,7 +231,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -267,8 +267,8 @@ function f4() {
 }
 //// [F5.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -297,7 +297,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -353,8 +353,8 @@ function f5() {
 }
 //// [F6.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -383,7 +383,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -407,8 +407,8 @@ function f6() {
 }
 //// [F7.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -437,7 +437,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es2015.js b/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es2015.js
index e89e9b9d6a89f..88ae6f0e40597 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es2015.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es2015.js
@@ -34,7 +34,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -52,7 +52,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -71,7 +71,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -102,7 +102,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -121,7 +121,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -152,7 +152,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -171,7 +171,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js b/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js
index 699df6cff0b1b..e4076be6c7a0b 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js
@@ -31,8 +31,8 @@ const f7 = async function * () {
 
 //// [F1.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -61,7 +61,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -79,8 +79,8 @@ var f1 = function () {
 };
 //// [F2.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -109,7 +109,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -134,8 +134,8 @@ var f2 = function () {
 };
 //// [F3.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -164,7 +164,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -189,8 +189,8 @@ var f3 = function () {
 };
 //// [F4.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -231,7 +231,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -267,8 +267,8 @@ var f4 = function () {
 };
 //// [F5.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -297,7 +297,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -353,8 +353,8 @@ var f5 = function () {
 };
 //// [F6.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -383,7 +383,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -407,8 +407,8 @@ var f6 = function () {
 };
 //// [F7.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -437,7 +437,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es2015.js b/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es2015.js
index 97ea27906a2c4..e24410353e555 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es2015.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es2015.js
@@ -48,7 +48,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -68,7 +68,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -89,7 +89,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -122,7 +122,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -143,7 +143,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -176,7 +176,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -197,7 +197,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js b/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js
index f65bf2d3caea3..194c26f59da1f 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js
@@ -45,8 +45,8 @@ const o7 = {
 
 //// [O1.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -75,7 +75,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -95,8 +95,8 @@ var o1 = {
 };
 //// [O2.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -125,7 +125,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -152,8 +152,8 @@ var o2 = {
 };
 //// [O3.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -182,7 +182,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -209,8 +209,8 @@ var o3 = {
 };
 //// [O4.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -251,7 +251,7 @@ var __asyncDelegator = (this && this.__asyncDelegator) || function (o) {
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -289,8 +289,8 @@ var o4 = {
 };
 //// [O5.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -319,7 +319,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -377,8 +377,8 @@ var o5 = {
 };
 //// [O6.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -407,7 +407,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -433,8 +433,8 @@ var o6 = {
 };
 //// [O7.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -463,7 +463,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.forAwait(target=es2015).js b/tests/baselines/reference/emitter.forAwait(target=es2015).js
index 5e77358f5efab..1fe4ae6da47bd 100644
--- a/tests/baselines/reference/emitter.forAwait(target=es2015).js
+++ b/tests/baselines/reference/emitter.forAwait(target=es2015).js
@@ -136,7 +136,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -177,7 +177,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -257,7 +257,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -300,7 +300,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.forAwait(target=es2017).js b/tests/baselines/reference/emitter.forAwait(target=es2017).js
index 9477434034b60..76499a01b26fe 100644
--- a/tests/baselines/reference/emitter.forAwait(target=es2017).js
+++ b/tests/baselines/reference/emitter.forAwait(target=es2017).js
@@ -114,7 +114,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -155,7 +155,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -224,7 +224,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -267,7 +267,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/emitter.forAwait(target=es5).js b/tests/baselines/reference/emitter.forAwait(target=es5).js
index da767cdc76492..212f6b4eeb990 100644
--- a/tests/baselines/reference/emitter.forAwait(target=es5).js
+++ b/tests/baselines/reference/emitter.forAwait(target=es5).js
@@ -61,8 +61,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -147,8 +147,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -224,8 +224,8 @@ function f2() {
 }
 //// [file3.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -261,7 +261,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -314,8 +314,8 @@ function f3() {
 }
 //// [file4.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -351,7 +351,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -413,8 +413,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -491,8 +491,8 @@ function f5() {
 }
 //// [file6.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -528,7 +528,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
@@ -582,8 +582,8 @@ function f6() {
 }
 //// [file7.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -619,7 +619,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/es5-asyncFunction.js b/tests/baselines/reference/es5-asyncFunction.js
index df6b0627cd566..9b262e16c8844 100644
--- a/tests/baselines/reference/es5-asyncFunction.js
+++ b/tests/baselines/reference/es5-asyncFunction.js
@@ -21,8 +21,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/es5-asyncFunctionLongObjectLiteral.js b/tests/baselines/reference/es5-asyncFunctionLongObjectLiteral.js
index 76cbea45560a7..48fdc5eb3600e 100644
--- a/tests/baselines/reference/es5-asyncFunctionLongObjectLiteral.js
+++ b/tests/baselines/reference/es5-asyncFunctionLongObjectLiteral.js
@@ -41,8 +41,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/es5-importHelpersAsyncFunctions.js b/tests/baselines/reference/es5-importHelpersAsyncFunctions.js
index 472c206c08ef1..03a239f92195d 100644
--- a/tests/baselines/reference/es5-importHelpersAsyncFunctions.js
+++ b/tests/baselines/reference/es5-importHelpersAsyncFunctions.js
@@ -40,8 +40,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/exportDefaultFunctionInNamespace.js b/tests/baselines/reference/exportDefaultFunctionInNamespace.js
index 0ef66b3be8402..a0746a0e49282 100644
--- a/tests/baselines/reference/exportDefaultFunctionInNamespace.js
+++ b/tests/baselines/reference/exportDefaultFunctionInNamespace.js
@@ -21,8 +21,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/expressionsForbiddenInParameterInitializers.js b/tests/baselines/reference/expressionsForbiddenInParameterInitializers.js
index 851d68ec37295..986f220e6572f 100644
--- a/tests/baselines/reference/expressionsForbiddenInParameterInitializers.js
+++ b/tests/baselines/reference/expressionsForbiddenInParameterInitializers.js
@@ -20,8 +20,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/forAwaitPerIterationBindingDownlevel.js b/tests/baselines/reference/forAwaitPerIterationBindingDownlevel.js
index 0f14a1b85df58..b9d78e748190a 100644
--- a/tests/baselines/reference/forAwaitPerIterationBindingDownlevel.js
+++ b/tests/baselines/reference/forAwaitPerIterationBindingDownlevel.js
@@ -37,8 +37,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -67,7 +67,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/importAttributes7.js b/tests/baselines/reference/importAttributes7.js
index 66ff33e5bc507..30f45f2386d47 100644
--- a/tests/baselines/reference/importAttributes7.js
+++ b/tests/baselines/reference/importAttributes7.js
@@ -35,8 +35,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionAsyncES5AMD.js b/tests/baselines/reference/importCallExpressionAsyncES5AMD.js
index 44a3dcc0619ff..4a458837a45ac 100644
--- a/tests/baselines/reference/importCallExpressionAsyncES5AMD.js
+++ b/tests/baselines/reference/importCallExpressionAsyncES5AMD.js
@@ -41,8 +41,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionAsyncES5CJS.js b/tests/baselines/reference/importCallExpressionAsyncES5CJS.js
index a816ecf6e46d0..4f2657547fe75 100644
--- a/tests/baselines/reference/importCallExpressionAsyncES5CJS.js
+++ b/tests/baselines/reference/importCallExpressionAsyncES5CJS.js
@@ -42,8 +42,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionAsyncES5System.js b/tests/baselines/reference/importCallExpressionAsyncES5System.js
index f701d06d2d4b8..352be31696e94 100644
--- a/tests/baselines/reference/importCallExpressionAsyncES5System.js
+++ b/tests/baselines/reference/importCallExpressionAsyncES5System.js
@@ -43,8 +43,8 @@ System.register([], function (exports_1, context_1) {
         });
     };
     var __generator = (this && this.__generator) || function (thisArg, body) {
-        var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-        return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+        var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+        return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
         function verb(n) { return function (v) { return step([n, v]); }; }
         function step(op) {
             if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionAsyncES5UMD.js b/tests/baselines/reference/importCallExpressionAsyncES5UMD.js
index 707b41f01ee3b..799fb08ad48dc 100644
--- a/tests/baselines/reference/importCallExpressionAsyncES5UMD.js
+++ b/tests/baselines/reference/importCallExpressionAsyncES5UMD.js
@@ -41,8 +41,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionNestedAMD2.js b/tests/baselines/reference/importCallExpressionNestedAMD2.js
index 3200a5831d936..4f90f4e7732a2 100644
--- a/tests/baselines/reference/importCallExpressionNestedAMD2.js
+++ b/tests/baselines/reference/importCallExpressionNestedAMD2.js
@@ -25,8 +25,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionNestedCJS2.js b/tests/baselines/reference/importCallExpressionNestedCJS2.js
index a40cf58f67480..5d2371ea723d5 100644
--- a/tests/baselines/reference/importCallExpressionNestedCJS2.js
+++ b/tests/baselines/reference/importCallExpressionNestedCJS2.js
@@ -23,8 +23,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionNestedES20152.js b/tests/baselines/reference/importCallExpressionNestedES20152.js
index 7d52515fd233b..07e9f0ced120e 100644
--- a/tests/baselines/reference/importCallExpressionNestedES20152.js
+++ b/tests/baselines/reference/importCallExpressionNestedES20152.js
@@ -21,8 +21,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionNestedES20202.js b/tests/baselines/reference/importCallExpressionNestedES20202.js
index 619b9b105a5c0..999f8ce28e6be 100644
--- a/tests/baselines/reference/importCallExpressionNestedES20202.js
+++ b/tests/baselines/reference/importCallExpressionNestedES20202.js
@@ -22,8 +22,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionNestedSystem2.js b/tests/baselines/reference/importCallExpressionNestedSystem2.js
index 62dc40ce6ac20..1490a4690022d 100644
--- a/tests/baselines/reference/importCallExpressionNestedSystem2.js
+++ b/tests/baselines/reference/importCallExpressionNestedSystem2.js
@@ -31,8 +31,8 @@ System.register([], function (exports_1, context_1) {
         });
     };
     var __generator = (this && this.__generator) || function (thisArg, body) {
-        var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-        return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+        var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+        return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
         function verb(n) { return function (v) { return step([n, v]); }; }
         function step(op) {
             if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionNestedUMD2.js b/tests/baselines/reference/importCallExpressionNestedUMD2.js
index 812cf0aa1c62f..c74e8d9eda23e 100644
--- a/tests/baselines/reference/importCallExpressionNestedUMD2.js
+++ b/tests/baselines/reference/importCallExpressionNestedUMD2.js
@@ -33,8 +33,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importCallExpressionNoModuleKindSpecified.js b/tests/baselines/reference/importCallExpressionNoModuleKindSpecified.js
index 08338407d4134..e7bf6909ce642 100644
--- a/tests/baselines/reference/importCallExpressionNoModuleKindSpecified.js
+++ b/tests/baselines/reference/importCallExpressionNoModuleKindSpecified.js
@@ -55,8 +55,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importMeta(module=commonjs,target=es5).js b/tests/baselines/reference/importMeta(module=commonjs,target=es5).js
index f2728bb75ae20..6d5e4033ca07c 100644
--- a/tests/baselines/reference/importMeta(module=commonjs,target=es5).js
+++ b/tests/baselines/reference/importMeta(module=commonjs,target=es5).js
@@ -50,8 +50,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importMeta(module=es2020,target=es5).js b/tests/baselines/reference/importMeta(module=es2020,target=es5).js
index 7cdf12ba8fe0a..03e7011012f38 100644
--- a/tests/baselines/reference/importMeta(module=es2020,target=es5).js
+++ b/tests/baselines/reference/importMeta(module=es2020,target=es5).js
@@ -49,8 +49,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importMeta(module=esnext,target=es5).js b/tests/baselines/reference/importMeta(module=esnext,target=es5).js
index 7cdf12ba8fe0a..03e7011012f38 100644
--- a/tests/baselines/reference/importMeta(module=esnext,target=es5).js
+++ b/tests/baselines/reference/importMeta(module=esnext,target=es5).js
@@ -49,8 +49,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/importMeta(module=system,target=es5).js b/tests/baselines/reference/importMeta(module=system,target=es5).js
index 2be9428dee726..b854483f66f5c 100644
--- a/tests/baselines/reference/importMeta(module=system,target=es5).js
+++ b/tests/baselines/reference/importMeta(module=system,target=es5).js
@@ -51,8 +51,8 @@ System.register([], function (exports_1, context_1) {
         });
     };
     var __generator = (this && this.__generator) || function (thisArg, body) {
-        var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-        return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+        var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+        return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
         function verb(n) { return function (v) { return step([n, v]); }; }
         function step(op) {
             if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/invalidContinueInDownlevelAsync.js b/tests/baselines/reference/invalidContinueInDownlevelAsync.js
index 1bf7a7a88e549..7aa96b7fc6c1c 100644
--- a/tests/baselines/reference/invalidContinueInDownlevelAsync.js
+++ b/tests/baselines/reference/invalidContinueInDownlevelAsync.js
@@ -21,8 +21,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/jsFileCompilationAwaitModifier.js b/tests/baselines/reference/jsFileCompilationAwaitModifier.js
index 148037d7006df..92361660afc56 100644
--- a/tests/baselines/reference/jsFileCompilationAwaitModifier.js
+++ b/tests/baselines/reference/jsFileCompilationAwaitModifier.js
@@ -23,8 +23,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/jsxElementType.js b/tests/baselines/reference/jsxElementType.js
index b2864d2740ce0..6d8349d54728a 100644
--- a/tests/baselines/reference/jsxElementType.js
+++ b/tests/baselines/reference/jsxElementType.js
@@ -141,8 +141,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/labeledStatementWithLabel.js b/tests/baselines/reference/labeledStatementWithLabel.js
index ba62abb97dbf1..f384e217dbb20 100644
--- a/tests/baselines/reference/labeledStatementWithLabel.js
+++ b/tests/baselines/reference/labeledStatementWithLabel.js
@@ -27,8 +27,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/legacyNodeModulesExportsSpecifierGenerationConditions.js b/tests/baselines/reference/legacyNodeModulesExportsSpecifierGenerationConditions.js
index b78501533ba4c..b942776c84403 100644
--- a/tests/baselines/reference/legacyNodeModulesExportsSpecifierGenerationConditions.js
+++ b/tests/baselines/reference/legacyNodeModulesExportsSpecifierGenerationConditions.js
@@ -43,8 +43,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/neverAsDiscriminantType(strict=false).js b/tests/baselines/reference/neverAsDiscriminantType(strict=false).js
index df00f302ae753..61e0670ff721d 100644
--- a/tests/baselines/reference/neverAsDiscriminantType(strict=false).js
+++ b/tests/baselines/reference/neverAsDiscriminantType(strict=false).js
@@ -79,8 +79,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/neverAsDiscriminantType(strict=true).js b/tests/baselines/reference/neverAsDiscriminantType(strict=true).js
index df00f302ae753..61e0670ff721d 100644
--- a/tests/baselines/reference/neverAsDiscriminantType(strict=true).js
+++ b/tests/baselines/reference/neverAsDiscriminantType(strict=true).js
@@ -79,8 +79,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/objectRestSpread.js b/tests/baselines/reference/objectRestSpread.js
index 5908b8d2d419e..a689b3f57614a 100644
--- a/tests/baselines/reference/objectRestSpread.js
+++ b/tests/baselines/reference/objectRestSpread.js
@@ -40,7 +40,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/operationsAvailableOnPromisedType.js b/tests/baselines/reference/operationsAvailableOnPromisedType.js
index 8ba23a7a47c6e..c84b83aed12d3 100644
--- a/tests/baselines/reference/operationsAvailableOnPromisedType.js
+++ b/tests/baselines/reference/operationsAvailableOnPromisedType.js
@@ -42,8 +42,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/parenthesizedAsyncArrowFunction.js b/tests/baselines/reference/parenthesizedAsyncArrowFunction.js
index 522b34f977925..e4fd9b3826362 100644
--- a/tests/baselines/reference/parenthesizedAsyncArrowFunction.js
+++ b/tests/baselines/reference/parenthesizedAsyncArrowFunction.js
@@ -18,8 +18,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/privateNamesIncompatibleModifiers.js b/tests/baselines/reference/privateNamesIncompatibleModifiers.js
index 6b6c916a43b37..7db58dd9ddb69 100644
--- a/tests/baselines/reference/privateNamesIncompatibleModifiers.js
+++ b/tests/baselines/reference/privateNamesIncompatibleModifiers.js
@@ -51,7 +51,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/promiseDefinitionTest.js b/tests/baselines/reference/promiseDefinitionTest.js
index f2d4d10dfe92e..ef7cd20fd9ef2 100644
--- a/tests/baselines/reference/promiseDefinitionTest.js
+++ b/tests/baselines/reference/promiseDefinitionTest.js
@@ -17,8 +17,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/reactReduxLikeDeferredInferenceAllowsAssignment.js b/tests/baselines/reference/reactReduxLikeDeferredInferenceAllowsAssignment.js
index 6283c4097c898..b000368f44808 100644
--- a/tests/baselines/reference/reactReduxLikeDeferredInferenceAllowsAssignment.js
+++ b/tests/baselines/reference/reactReduxLikeDeferredInferenceAllowsAssignment.js
@@ -176,8 +176,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.js b/tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.js
index 429f2bf360800..18694bfa14cb4 100644
--- a/tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.js
+++ b/tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.js
@@ -10,8 +10,8 @@ call(function* (a: 'a') { }); // error, 2nd argument required
 
 //// [spreadOfParamsFromGeneratorMakesRequiredParams.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/templateStringWithEmbeddedYieldKeyword.js b/tests/baselines/reference/templateStringWithEmbeddedYieldKeyword.js
index 9165eaf7d05d0..3c767adb91b29 100644
--- a/tests/baselines/reference/templateStringWithEmbeddedYieldKeyword.js
+++ b/tests/baselines/reference/templateStringWithEmbeddedYieldKeyword.js
@@ -9,8 +9,8 @@ function* gen {
 
 //// [templateStringWithEmbeddedYieldKeyword.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/transformNestedGeneratorsWithTry.js b/tests/baselines/reference/transformNestedGeneratorsWithTry.js
index fafab23513f62..03e601481e87c 100644
--- a/tests/baselines/reference/transformNestedGeneratorsWithTry.js
+++ b/tests/baselines/reference/transformNestedGeneratorsWithTry.js
@@ -34,8 +34,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/usingDeclarations.1(target=es2015).js b/tests/baselines/reference/usingDeclarations.1(target=es2015).js
index a32dd5c254fb5..e007092478438 100644
--- a/tests/baselines/reference/usingDeclarations.1(target=es2015).js
+++ b/tests/baselines/reference/usingDeclarations.1(target=es2015).js
@@ -219,7 +219,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/usingDeclarations.1(target=es2017).js b/tests/baselines/reference/usingDeclarations.1(target=es2017).js
index afc9c8a3d9d92..6759e29ae4561 100644
--- a/tests/baselines/reference/usingDeclarations.1(target=es2017).js
+++ b/tests/baselines/reference/usingDeclarations.1(target=es2017).js
@@ -210,7 +210,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/usingDeclarations.1(target=es5).js b/tests/baselines/reference/usingDeclarations.1(target=es5).js
index 96d3e7e0311e7..d9a8c2e561e93 100644
--- a/tests/baselines/reference/usingDeclarations.1(target=es5).js
+++ b/tests/baselines/reference/usingDeclarations.1(target=es5).js
@@ -179,8 +179,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
@@ -261,7 +261,7 @@ var __await = (this && this.__await) || function (v) { return this instanceof __
 var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    return i = Object.create((typeof AsyncIterator === "function" ? AsyncIterator : Object).prototype), verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
     function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
     function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
diff --git a/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es5).js b/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es5).js
index 73e60e2988694..31d3c5ab036bb 100644
--- a/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es5).js
+++ b/tests/baselines/reference/usingDeclarationsInForAwaitOf(target=es5).js
@@ -18,8 +18,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
diff --git a/tests/baselines/reference/yieldInForInInDownlevelGenerator.js b/tests/baselines/reference/yieldInForInInDownlevelGenerator.js
index 205d535ba8569..db5011137f0fc 100644
--- a/tests/baselines/reference/yieldInForInInDownlevelGenerator.js
+++ b/tests/baselines/reference/yieldInForInInDownlevelGenerator.js
@@ -12,8 +12,8 @@ function* gen() {
 
 //// [yieldInForInInDownlevelGenerator.js]
 var __generator = (this && this.__generator) || function (thisArg, body) {
-    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
-    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");

From 1f54d0a9356d92e6f2fe63d5991c50e7892f3f12 Mon Sep 17 00:00:00 2001
From: "Oleksandr T." <oleksandr.tarasiuk@outlook.com>
Date: Thu, 8 Aug 2024 19:37:57 +0300
Subject: [PATCH 03/11] fix(59484): Constructor overload still present in
 emitted JS (#59491)

---
 src/compiler/factory/nodeFactory.ts           | 13 +++++---
 .../reference/constructorOverloads9.js        | 19 ++++++++++++
 .../reference/constructorOverloads9.symbols   | 21 +++++++++++++
 .../reference/constructorOverloads9.types     | 30 +++++++++++++++++++
 tests/cases/compiler/constructorOverloads9.ts |  8 +++++
 5 files changed, 87 insertions(+), 4 deletions(-)
 create mode 100644 tests/baselines/reference/constructorOverloads9.js
 create mode 100644 tests/baselines/reference/constructorOverloads9.symbols
 create mode 100644 tests/baselines/reference/constructorOverloads9.types
 create mode 100644 tests/cases/compiler/constructorOverloads9.ts

diff --git a/src/compiler/factory/nodeFactory.ts b/src/compiler/factory/nodeFactory.ts
index 8f3b15690f7e2..90b9071efe594 100644
--- a/src/compiler/factory/nodeFactory.ts
+++ b/src/compiler/factory/nodeFactory.ts
@@ -1985,10 +1985,15 @@ export function createNodeFactory(flags: NodeFactoryFlags, baseFactory: BaseNode
         node.parameters = createNodeArray(parameters);
         node.body = body;
 
-        node.transformFlags = propagateChildrenFlags(node.modifiers) |
-            propagateChildrenFlags(node.parameters) |
-            (propagateChildFlags(node.body) & ~TransformFlags.ContainsPossibleTopLevelAwait) |
-            TransformFlags.ContainsES2015;
+        if (!node.body) {
+            node.transformFlags = TransformFlags.ContainsTypeScript;
+        }
+        else {
+            node.transformFlags = propagateChildrenFlags(node.modifiers) |
+                propagateChildrenFlags(node.parameters) |
+                (propagateChildFlags(node.body) & ~TransformFlags.ContainsPossibleTopLevelAwait) |
+                TransformFlags.ContainsES2015;
+        }
 
         node.typeParameters = undefined; // initialized by parser for grammar errors
         node.type = undefined; // initialized by parser for grammar errors
diff --git a/tests/baselines/reference/constructorOverloads9.js b/tests/baselines/reference/constructorOverloads9.js
new file mode 100644
index 0000000000000..868263711d818
--- /dev/null
+++ b/tests/baselines/reference/constructorOverloads9.js
@@ -0,0 +1,19 @@
+//// [tests/cases/compiler/constructorOverloads9.ts] ////
+
+//// [constructorOverloads9.ts]
+export class C {
+    a;
+    constructor();
+    constructor(x = '') {
+        this.a = x;
+    }
+}
+
+
+//// [constructorOverloads9.js]
+export class C {
+    a;
+    constructor(x = '') {
+        this.a = x;
+    }
+}
diff --git a/tests/baselines/reference/constructorOverloads9.symbols b/tests/baselines/reference/constructorOverloads9.symbols
new file mode 100644
index 0000000000000..27527a8d823dd
--- /dev/null
+++ b/tests/baselines/reference/constructorOverloads9.symbols
@@ -0,0 +1,21 @@
+//// [tests/cases/compiler/constructorOverloads9.ts] ////
+
+=== constructorOverloads9.ts ===
+export class C {
+>C : Symbol(C, Decl(constructorOverloads9.ts, 0, 0))
+
+    a;
+>a : Symbol(C.a, Decl(constructorOverloads9.ts, 0, 16))
+
+    constructor();
+    constructor(x = '') {
+>x : Symbol(x, Decl(constructorOverloads9.ts, 3, 16))
+
+        this.a = x;
+>this.a : Symbol(C.a, Decl(constructorOverloads9.ts, 0, 16))
+>this : Symbol(C, Decl(constructorOverloads9.ts, 0, 0))
+>a : Symbol(C.a, Decl(constructorOverloads9.ts, 0, 16))
+>x : Symbol(x, Decl(constructorOverloads9.ts, 3, 16))
+    }
+}
+
diff --git a/tests/baselines/reference/constructorOverloads9.types b/tests/baselines/reference/constructorOverloads9.types
new file mode 100644
index 0000000000000..0f5459e0d816a
--- /dev/null
+++ b/tests/baselines/reference/constructorOverloads9.types
@@ -0,0 +1,30 @@
+//// [tests/cases/compiler/constructorOverloads9.ts] ////
+
+=== constructorOverloads9.ts ===
+export class C {
+>C : C
+>  : ^
+
+    a;
+>a : any
+
+    constructor();
+    constructor(x = '') {
+>x : string
+>  : ^^^^^^
+>'' : ""
+>   : ^^
+
+        this.a = x;
+>this.a = x : string
+>           : ^^^^^^
+>this.a : any
+>this : this
+>     : ^^^^
+>a : any
+>  : ^^^
+>x : string
+>  : ^^^^^^
+    }
+}
+
diff --git a/tests/cases/compiler/constructorOverloads9.ts b/tests/cases/compiler/constructorOverloads9.ts
new file mode 100644
index 0000000000000..3ac84ad8964db
--- /dev/null
+++ b/tests/cases/compiler/constructorOverloads9.ts
@@ -0,0 +1,8 @@
+// @target: esnext
+export class C {
+    a;
+    constructor();
+    constructor(x = '') {
+        this.a = x;
+    }
+}

From 5e9e6ad2953e8097cb2e90283f656988f2ddd563 Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Thu, 8 Aug 2024 09:38:10 -0700
Subject: [PATCH 04/11] Fix accidental relative imports from non namespace
 barrels (#59544)

---
 eslint.config.mjs                             |  8 ++
 scripts/eslint/rules/no-direct-import.cjs     | 81 +++++++++++++++++++
 .../fixMissingTypeAnnotationOnExports.ts      | 21 +++--
 src/services/pasteEdits.ts                    | 16 ++--
 src/services/refactors/moveToFile.ts          | 10 ++-
 src/services/stringCompletions.ts             |  3 +-
 6 files changed, 113 insertions(+), 26 deletions(-)
 create mode 100644 scripts/eslint/rules/no-direct-import.cjs

diff --git a/eslint.config.mjs b/eslint.config.mjs
index 13729d3ee83be..f2566c3b631f8 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -210,12 +210,20 @@ export default tseslint.config(
                 { name: "clearImmediate" },
                 { name: "performance" },
             ],
+            "local/no-direct-import": "error",
         },
     },
     {
         files: ["src/harness/**", "src/testRunner/**"],
         rules: {
             "no-restricted-globals": "off",
+            "local/no-direct-import": "off",
+        },
+    },
+    {
+        files: ["src/**/_namespaces/**"],
+        rules: {
+            "local/no-direct-import": "off",
         },
     },
     {
diff --git a/scripts/eslint/rules/no-direct-import.cjs b/scripts/eslint/rules/no-direct-import.cjs
new file mode 100644
index 0000000000000..614e67db30be3
--- /dev/null
+++ b/scripts/eslint/rules/no-direct-import.cjs
@@ -0,0 +1,81 @@
+const { createRule } = require("./utils.cjs");
+const path = require("path");
+
+/** @import { TSESTree } from "@typescript-eslint/utils" */
+void 0;
+
+module.exports = createRule({
+    name: "no-direct-import",
+    meta: {
+        docs: {
+            description: ``,
+        },
+        messages: {
+            noDirectImport: `This import relatively references another project; did you mean to import from a local _namespace module?`,
+        },
+        schema: [],
+        type: "problem",
+    },
+    defaultOptions: [],
+
+    create(context) {
+        const containingFileName = context.filename;
+        const containingDirectory = path.dirname(containingFileName);
+
+        /** @type {(node: TSESTree.ImportDeclaration | TSESTree.TSImportEqualsDeclaration) => void} */
+        const check = node => {
+            let source;
+            if (node.type === "TSImportEqualsDeclaration") {
+                const moduleReference = node.moduleReference;
+                if (
+                    moduleReference.type === "TSExternalModuleReference"
+                    && moduleReference.expression.type === "Literal"
+                    && typeof moduleReference.expression.value === "string"
+                ) {
+                    source = moduleReference.expression;
+                }
+            }
+            else {
+                source = node.source;
+            }
+
+            if (!source) return;
+
+            const p = source.value;
+
+            // These appear in place of public API imports.
+            if (p.endsWith("../typescript/typescript.js")) return;
+
+            // The below is similar to https://github.com/microsoft/DefinitelyTyped-tools/blob/main/packages/eslint-plugin/src/rules/no-bad-reference.ts
+
+            // Any relative path that goes to the wrong place will contain "..".
+            if (!p.includes("..")) return;
+
+            const parts = p.split("/");
+            let cwd = containingDirectory;
+            for (const part of parts) {
+                if (part === "" || part === ".") {
+                    continue;
+                }
+                if (part === "..") {
+                    cwd = path.dirname(cwd);
+                }
+                else {
+                    cwd = path.join(cwd, part);
+                }
+
+                if (path.basename(cwd) === "src") {
+                    context.report({
+                        messageId: "noDirectImport",
+                        node: source,
+                    });
+                }
+            }
+        };
+
+        return {
+            ImportDeclaration: check,
+            TSImportEqualsDeclaration: check,
+        };
+    },
+});
diff --git a/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts b/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts
index db117935dea2d..deea661f2e72a 100644
--- a/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts
+++ b/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts
@@ -1,3 +1,12 @@
+import {
+    createCodeFixAction,
+    createCombinedCodeActions,
+    createImportAdder,
+    eachDiagnostic,
+    registerCodeFix,
+    typePredicateToAutoImportableTypeNode,
+    typeToAutoImportableTypeNode,
+} from "../_namespaces/ts.codefix.js";
 import {
     ArrayBindingPattern,
     ArrayLiteralExpression,
@@ -97,17 +106,7 @@ import {
     VariableStatement,
     walkUpParenthesizedExpressions,
 } from "../_namespaces/ts.js";
-
-import {
-    createCodeFixAction,
-    createCombinedCodeActions,
-    createImportAdder,
-    eachDiagnostic,
-    registerCodeFix,
-    typePredicateToAutoImportableTypeNode,
-    typeToAutoImportableTypeNode,
-} from "../_namespaces/ts.codefix.js";
-import { getIdentifierForNode } from "../refactors/helpers.js";
+import { getIdentifierForNode } from "../_namespaces/ts.refactor.js";
 
 const fixId = "fixMissingTypeAnnotationOnExports";
 
diff --git a/src/services/pasteEdits.ts b/src/services/pasteEdits.ts
index f3b350816781e..e39a51bf45076 100644
--- a/src/services/pasteEdits.ts
+++ b/src/services/pasteEdits.ts
@@ -1,22 +1,20 @@
-import { findIndex } from "../compiler/core.js";
 import {
     CancellationToken,
-    Program,
-    SourceFile,
-    Statement,
-    SymbolFlags,
-    TextRange,
-    UserPreferences,
-} from "../compiler/types.js";
-import {
     codefix,
     Debug,
     fileShouldUseJavaScriptRequire,
+    findIndex,
     forEachChild,
     formatting,
     getQuotePreference,
     isIdentifier,
+    Program,
+    SourceFile,
+    Statement,
+    SymbolFlags,
     textChanges,
+    TextRange,
+    UserPreferences,
 } from "./_namespaces/ts.js";
 import { addTargetFileImports } from "./refactors/helpers.js";
 import {
diff --git a/src/services/refactors/moveToFile.ts b/src/services/refactors/moveToFile.ts
index da6d806a06f30..85c040013edcb 100644
--- a/src/services/refactors/moveToFile.ts
+++ b/src/services/refactors/moveToFile.ts
@@ -1,4 +1,3 @@
-import { getModuleSpecifier } from "../../compiler/_namespaces/ts.moduleSpecifiers.js";
 import {
     ApplicableRefactorInfo,
     arrayFrom,
@@ -118,6 +117,7 @@ import {
     ModifierLike,
     ModuleDeclaration,
     ModuleKind,
+    moduleSpecifiers,
     moduleSpecifierToValidIdentifier,
     NamedImportBindings,
     Node,
@@ -157,8 +157,10 @@ import {
     VariableDeclarationList,
     VariableStatement,
 } from "../_namespaces/ts.js";
-import { addTargetFileImports } from "../_namespaces/ts.refactor.js";
-import { registerRefactor } from "../refactorProvider.js";
+import {
+    addTargetFileImports,
+    registerRefactor,
+} from "../_namespaces/ts.refactor.js";
 
 const refactorNameForMoveToFile = "Move to file";
 const description = getLocaleSpecificMessage(Diagnostics.Move_to_file);
@@ -358,7 +360,7 @@ function updateImportsInOtherFiles(
 
                 if (getStringComparer(!program.useCaseSensitiveFileNames())(pathToTargetFileWithExtension, sourceFile.fileName) === Comparison.EqualTo) return;
 
-                const newModuleSpecifier = getModuleSpecifier(program.getCompilerOptions(), sourceFile, sourceFile.fileName, pathToTargetFileWithExtension, createModuleSpecifierResolutionHost(program, host));
+                const newModuleSpecifier = moduleSpecifiers.getModuleSpecifier(program.getCompilerOptions(), sourceFile, sourceFile.fileName, pathToTargetFileWithExtension, createModuleSpecifierResolutionHost(program, host));
                 const newImportDeclaration = filterImport(importNode, makeStringLiteral(newModuleSpecifier, quotePreference), shouldMove);
                 if (newImportDeclaration) changes.insertNodeAfter(sourceFile, statement, newImportDeclaration);
 
diff --git a/src/services/stringCompletions.ts b/src/services/stringCompletions.ts
index a26959d57f2dc..667cdf24ca8aa 100644
--- a/src/services/stringCompletions.ts
+++ b/src/services/stringCompletions.ts
@@ -1,4 +1,3 @@
-import { getModuleSpecifierPreferences } from "../compiler/moduleSpecifiers.js";
 import {
     CompletionKind,
     createCompletionDetails,
@@ -823,7 +822,7 @@ function getFilenameWithExtensionOption(name: string, program: Program, extensio
         return { name, extension: tryGetExtensionFromPath(name) };
     }
 
-    let allowedEndings = getModuleSpecifierPreferences(
+    let allowedEndings = moduleSpecifiers.getModuleSpecifierPreferences(
         { importModuleSpecifierEnding: extensionOptions.endingPreference },
         program,
         program.getCompilerOptions(),

From aa8a2c0bb45a84d59f5837a488669561517d9b13 Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Thu, 8 Aug 2024 10:04:34 -0700
Subject: [PATCH 05/11] Remove unused variable in ts transform (#59467)

---
 src/compiler/transformers/ts.ts | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/src/compiler/transformers/ts.ts b/src/compiler/transformers/ts.ts
index d2b3e1121f406..9549d5b322f5e 100644
--- a/src/compiler/transformers/ts.ts
+++ b/src/compiler/transformers/ts.ts
@@ -60,7 +60,6 @@ import {
     getStrictOptionValue,
     getTextOfNode,
     hasDecorators,
-    hasStaticModifier,
     hasSyntacticModifier,
     HeritageClause,
     Identifier,
@@ -266,7 +265,6 @@ export function transformTypeScript(context: TransformationContext) {
     let currentNamespaceContainerName: Identifier;
     let currentLexicalScope: SourceFile | Block | ModuleBlock | CaseBlock;
     let currentScopeFirstDeclarationsOfName: Map<__String, Node> | undefined;
-    let currentClassHasParameterProperties: boolean | undefined;
 
     /**
      * Keeps track of whether expression substitution has been enabled for specific edge cases.
@@ -323,7 +321,6 @@ export function transformTypeScript(context: TransformationContext) {
         // Save state
         const savedCurrentScope = currentLexicalScope;
         const savedCurrentScopeFirstDeclarationsOfName = currentScopeFirstDeclarationsOfName;
-        const savedCurrentClassHasParameterProperties = currentClassHasParameterProperties;
 
         // Handle state changes before visiting a node.
         onBeforeVisitNode(node);
@@ -336,7 +333,6 @@ export function transformTypeScript(context: TransformationContext) {
         }
 
         currentLexicalScope = savedCurrentScope;
-        currentClassHasParameterProperties = savedCurrentClassHasParameterProperties;
         return visited;
     }
 
@@ -1239,10 +1235,8 @@ export function transformTypeScript(context: TransformationContext) {
     function visitPropertyNameOfClassElement(member: ClassElement): PropertyName {
         const name = member.name!;
         // Computed property names need to be transformed into a hoisted variable when they are used more than once.
-        // The names are used more than once when:
-        //   - the property is non-static and its initializer is moved to the constructor (when there are parameter property assignments).
-        //   - the property has a decorator.
-        if (isComputedPropertyName(name) && ((!hasStaticModifier(member) && currentClassHasParameterProperties) || hasDecorators(member) && legacyDecorators)) {
+        // The names are used more than once when the property has a decorator.
+        if (legacyDecorators && isComputedPropertyName(name) && hasDecorators(member)) {
             const expression = visitNode(name.expression, visitor, isExpression);
             Debug.assert(expression);
             const innerExpression = skipPartiallyEmittedExpressions(expression);

From 5f79e16d33aff625258d5e018f6d1ba9c98b3307 Mon Sep 17 00:00:00 2001
From: Armando Aguirre <armando.aguirre@microsoft.com>
Date: Thu, 8 Aug 2024 13:19:24 -0700
Subject: [PATCH 06/11] Refactored node builder flags and tests (#59440)

Co-authored-by: Armando Aguirre Sepulveda <araguir@microsoft.com>
---
 src/compiler/checker.ts                       | 150 ++++++++++--------
 src/compiler/transformers/declarations.ts     |  16 +-
 src/compiler/types.ts                         |  33 ++--
 src/harness/typeWriter.ts                     |   2 +-
 .../codefixes/fixAddMissingConstraint.ts      |   2 +-
 src/services/codefixes/fixAddMissingMember.ts |   7 +-
 src/services/codefixes/fixAddMissingParam.ts  |   3 +-
 .../fixClassIncorrectlyImplementsInterface.ts |   2 +-
 .../fixMissingTypeAnnotationOnExports.ts      |  10 +-
 src/services/codefixes/helpers.ts             |  26 +--
 src/services/completions.ts                   |   2 +-
 src/services/refactors/extractSymbol.ts       |  15 +-
 .../refactors/inferFunctionReturnType.ts      |   5 +-
 src/services/utilities.ts                     |   3 +-
 14 files changed, 156 insertions(+), 120 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 4cdd0531b1c04..3c6713a826280 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -447,6 +447,7 @@ import {
     InterfaceDeclaration,
     InterfaceType,
     InterfaceTypeWithDeclaredMembers,
+    InternalNodeBuilderFlags,
     InternalSymbolName,
     IntersectionFlags,
     IntersectionType,
@@ -5916,6 +5917,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function symbolToString(symbol: Symbol, enclosingDeclaration?: Node, meaning?: SymbolFlags, flags: SymbolFormatFlags = SymbolFormatFlags.AllowAnyNodeKind, writer?: EmitTextWriter): string {
         let nodeFlags = NodeBuilderFlags.IgnoreErrors;
+        let internalNodeFlags = InternalNodeBuilderFlags.None;
         if (flags & SymbolFormatFlags.UseOnlyExternalAliasing) {
             nodeFlags |= NodeBuilderFlags.UseOnlyExternalAliasing;
         }
@@ -5926,16 +5928,16 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             nodeFlags |= NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope;
         }
         if (flags & SymbolFormatFlags.DoNotIncludeSymbolChain) {
-            nodeFlags |= NodeBuilderFlags.DoNotIncludeSymbolChain;
+            internalNodeFlags |= InternalNodeBuilderFlags.DoNotIncludeSymbolChain;
         }
         if (flags & SymbolFormatFlags.WriteComputedProps) {
-            nodeFlags |= NodeBuilderFlags.WriteComputedProps;
+            internalNodeFlags |= InternalNodeBuilderFlags.WriteComputedProps;
         }
         const builder = flags & SymbolFormatFlags.AllowAnyNodeKind ? nodeBuilder.symbolToNode : nodeBuilder.symbolToEntityName;
         return writer ? symbolToStringWorker(writer).getText() : usingSingleLineStringWriter(symbolToStringWorker);
 
         function symbolToStringWorker(writer: EmitTextWriter) {
-            const entity = builder(symbol, meaning!, enclosingDeclaration, nodeFlags)!; // TODO: GH#18217
+            const entity = builder(symbol, meaning!, enclosingDeclaration, nodeFlags, internalNodeFlags)!; // TODO: GH#18217
             // add neverAsciiEscape for GH#39027
             const printer = enclosingDeclaration?.kind === SyntaxKind.SourceFile
                 ? createPrinterWithRemoveCommentsNeverAsciiEscape()
@@ -5967,7 +5969,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function typeToString(type: Type, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.AllowUniqueESSymbolType | TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer: EmitTextWriter = createTextWriter("")): string {
         const noTruncation = compilerOptions.noErrorTruncation || flags & TypeFormatFlags.NoTruncation;
-        const typeNode = nodeBuilder.typeToTypeNode(type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | (noTruncation ? NodeBuilderFlags.NoTruncation : 0));
+        const typeNode = nodeBuilder.typeToTypeNode(type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | (noTruncation ? NodeBuilderFlags.NoTruncation : NodeBuilderFlags.None), /*internalFlags*/ undefined);
         if (typeNode === undefined) return Debug.fail("should always get typenode");
         // The unresolved type gets a synthesized comment on `any` to hint to users that it's not a plain `any`.
         // Otherwise, we always strip comments out.
@@ -6018,20 +6020,20 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     }
     function createNodeBuilder() {
         return {
-            typeToTypeNode: (type: Type, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeToTypeNodeHelper(type, context)),
-            typePredicateToTypePredicateNode: (typePredicate: TypePredicate, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typePredicateToTypePredicateNodeHelper(typePredicate, context)),
-            expressionOrTypeToTypeNode: (expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => expressionOrTypeToTypeNode(context, expr, type, addUndefined)),
-            serializeTypeForDeclaration: (declaration: Declaration, type: Type, symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeTypeForDeclaration(context, declaration, type, symbol)),
-            serializeReturnTypeForSignature: (signature: Signature, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeReturnTypeForSignature(context, signature)),
-            indexInfoToIndexSignatureDeclaration: (indexInfo: IndexInfo, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => indexInfoToIndexSignatureDeclarationHelper(indexInfo, context, /*typeNode*/ undefined)),
-            signatureToSignatureDeclaration: (signature: Signature, kind: SignatureDeclaration["kind"], enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => signatureToSignatureDeclarationHelper(signature, kind, context)),
-            symbolToEntityName: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToName(symbol, context, meaning, /*expectsIdentifier*/ false)),
-            symbolToExpression: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToExpression(symbol, context, meaning)),
-            symbolToTypeParameterDeclarations: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParametersToTypeParameterDeclarations(symbol, context)),
-            symbolToParameterDeclaration: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToParameterDeclaration(symbol, context)),
-            typeParameterToDeclaration: (parameter: TypeParameter, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParameterToDeclaration(parameter, context)),
-            symbolTableToDeclarationStatements: (symbolTable: SymbolTable, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolTableToDeclarationStatements(symbolTable, context)),
-            symbolToNode: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToNode(symbol, context, meaning)),
+            typeToTypeNode: (type: Type, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => typeToTypeNodeHelper(type, context)),
+            typePredicateToTypePredicateNode: (typePredicate: TypePredicate, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => typePredicateToTypePredicateNodeHelper(typePredicate, context)),
+            expressionOrTypeToTypeNode: (expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => expressionOrTypeToTypeNode(context, expr, type, addUndefined)),
+            serializeTypeForDeclaration: (declaration: Declaration, type: Type, symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => serializeTypeForDeclaration(context, declaration, type, symbol)),
+            serializeReturnTypeForSignature: (signature: Signature, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => serializeReturnTypeForSignature(context, signature)),
+            indexInfoToIndexSignatureDeclaration: (indexInfo: IndexInfo, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => indexInfoToIndexSignatureDeclarationHelper(indexInfo, context, /*typeNode*/ undefined)),
+            signatureToSignatureDeclaration: (signature: Signature, kind: SignatureDeclaration["kind"], enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => signatureToSignatureDeclarationHelper(signature, kind, context)),
+            symbolToEntityName: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => symbolToName(symbol, context, meaning, /*expectsIdentifier*/ false)),
+            symbolToExpression: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => symbolToExpression(symbol, context, meaning)),
+            symbolToTypeParameterDeclarations: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => typeParametersToTypeParameterDeclarations(symbol, context)),
+            symbolToParameterDeclaration: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => symbolToParameterDeclaration(symbol, context)),
+            typeParameterToDeclaration: (parameter: TypeParameter, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => typeParameterToDeclaration(parameter, context)),
+            symbolTableToDeclarationStatements: (symbolTable: SymbolTable, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => symbolTableToDeclarationStatements(symbolTable, context)),
+            symbolToNode: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, internalFlags, tracker, context => symbolToNode(symbol, context, meaning)),
         };
 
         function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes?: false): Type;
@@ -6071,13 +6073,13 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
          * Same as expressionOrTypeToTypeNodeHelper, but also checks if the expression can be syntactically typed.
          */
         function expressionOrTypeToTypeNode(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) {
-            const oldFlags = context.flags;
-            if (expr && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) {
+            const restoreFlags = saveRestoreFlags(context);
+            if (expr && !(context.internalFlags & InternalNodeBuilderFlags.NoSyntacticPrinter)) {
                 syntacticNodeBuilder.serializeTypeOfExpression(expr, context, addUndefined);
             }
-            context.flags |= NodeBuilderFlags.NoSyntacticPrinter;
+            context.internalFlags |= InternalNodeBuilderFlags.NoSyntacticPrinter;
             const result = expressionOrTypeToTypeNodeHelper(context, expr, type, addUndefined);
-            context.flags = oldFlags;
+            restoreFlags();
             return result;
         }
         function expressionOrTypeToTypeNodeHelper(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) {
@@ -6145,7 +6147,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
 
         function symbolToNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) {
-            if (context.flags & NodeBuilderFlags.WriteComputedProps) {
+            if (context.internalFlags & InternalNodeBuilderFlags.WriteComputedProps) {
                 if (symbol.valueDeclaration) {
                     const name = getNameOfDeclaration(symbol.valueDeclaration);
                     if (name && isComputedPropertyName(name)) return name;
@@ -6159,14 +6161,15 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             return symbolToExpression(symbol, context, meaning);
         }
 
-        function withContext<T>(enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker: SymbolTracker | undefined, cb: (context: NodeBuilderContext) => T): T | undefined {
+        function withContext<T>(enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, internalFlags: InternalNodeBuilderFlags | undefined, tracker: SymbolTracker | undefined, cb: (context: NodeBuilderContext) => T): T | undefined {
             const moduleResolverHost = tracker?.trackSymbol ? tracker.moduleResolverHost :
-                flags! & NodeBuilderFlags.DoNotIncludeSymbolChain ? createBasicNodeBuilderModuleSpecifierResolutionHost(host) :
+                (internalFlags || InternalNodeBuilderFlags.None) & InternalNodeBuilderFlags.DoNotIncludeSymbolChain ? createBasicNodeBuilderModuleSpecifierResolutionHost(host) :
                 undefined;
             const context: NodeBuilderContext = {
                 enclosingDeclaration,
                 enclosingFile: enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration),
                 flags: flags || NodeBuilderFlags.None,
+                internalFlags: internalFlags || InternalNodeBuilderFlags.None,
                 tracker: undefined!,
                 encounteredError: false,
                 reportedDiagnostic: false,
@@ -6197,15 +6200,27 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             return context.encounteredError ? undefined : resultingNode;
         }
 
+        function saveRestoreFlags(context: NodeBuilderContext) {
+            const flags = context.flags;
+            const internalFlags = context.internalFlags;
+
+            return restore;
+
+            function restore() {
+                context.flags = flags;
+                context.internalFlags = internalFlags;
+            }
+        }
+
         function checkTruncationLength(context: NodeBuilderContext): boolean {
             if (context.truncating) return context.truncating;
             return context.truncating = context.approximateLength > ((context.flags & NodeBuilderFlags.NoTruncation) ? noTruncationMaximumTruncationLength : defaultMaximumTruncationLength);
         }
 
         function typeToTypeNodeHelper(type: Type, context: NodeBuilderContext): TypeNode {
-            const savedFlags = context.flags;
+            const restoreFlags = saveRestoreFlags(context);
             const typeNode = typeToTypeNodeWorker(type, context);
-            context.flags = savedFlags;
+            restoreFlags();
             return typeNode;
         }
 
@@ -6682,7 +6697,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 }
 
                 const links = context.enclosingDeclaration && getNodeLinks(context.enclosingDeclaration);
-                const key = `${getTypeId(type)}|${context.flags}`;
+                const key = `${getTypeId(type)}|${context.flags}|${context.internalFlags}`;
                 if (links) {
                     links.serializedTypes ||= new Map();
                 }
@@ -6803,10 +6818,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     return typeToTypeNodeHelper(getIntersectionType(types), context);
                 }
 
-                const savedFlags = context.flags;
+                const restoreFlags = saveRestoreFlags(context);
                 context.flags |= NodeBuilderFlags.InObjectTypeLiteral;
                 const members = createTypeNodesFromResolvedType(resolved);
-                context.flags = savedFlags;
+                restoreFlags();
                 const typeLiteralNode = factory.createTypeLiteralNode(members);
                 context.approximateLength += 2;
                 setEmitFlags(typeLiteralNode, (context.flags & NodeBuilderFlags.MultilineObjectLiterals) ? 0 : EmitFlags.SingleLine);
@@ -6887,10 +6902,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                             // the default outer type arguments), we don't show the group.
                             if (!rangeEquals(outerTypeParameters, typeArguments, start, i)) {
                                 const typeArgumentSlice = mapToTypeNodes(typeArguments.slice(start, i), context);
-                                const flags = context.flags;
+                                const restoreFlags = saveRestoreFlags(context);
                                 context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences;
                                 const ref = symbolToTypeNode(parent, context, SymbolFlags.Type, typeArgumentSlice) as TypeReferenceNode | ImportTypeNode;
-                                context.flags = flags;
+                                restoreFlags();
                                 resultType = !resultType ? ref : appendReferenceToType(resultType, ref as TypeReferenceNode);
                             }
                         }
@@ -6930,10 +6945,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
                         typeArgumentNodes = mapToTypeNodes(typeArguments.slice(i, typeParameterCount), context);
                     }
-                    const flags = context.flags;
+                    const restoreFlags = saveRestoreFlags(context);
                     context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences;
                     const finalRef = symbolToTypeNode(type.symbol, context, SymbolFlags.Type, typeArgumentNodes);
-                    context.flags = flags;
+                    restoreFlags();
                     return !resultType ? finalRef : appendReferenceToType(resultType, finalRef as TypeReferenceNode);
                 }
             }
@@ -7260,7 +7275,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     // once while referring to different types. If so, regenerate the
                     // type node for each entry by that name with the
                     // `UseFullyQualifiedType` flag enabled.
-                    const saveContextFlags = context.flags;
+                    const restoreFlags = saveRestoreFlags(context);
                     context.flags |= NodeBuilderFlags.UseFullyQualifiedType;
                     seenNames.forEach(types => {
                         if (!arrayIsHomogeneous(types, ([a], [b]) => typesAreSameReference(a, b))) {
@@ -7269,7 +7284,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                             }
                         }
                     });
-                    context.flags = saveContextFlags;
+                    restoreFlags();
                 }
 
                 return result;
@@ -7329,7 +7344,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 typeParameters = signature.typeParameters && signature.typeParameters.map(parameter => typeParameterToDeclaration(parameter, context));
             }
 
-            const flags = context.flags;
+            const restoreFlags = saveRestoreFlags(context);
             context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // SuppressAnyReturnType should only apply to the signature `return` position
             // If the expanded parameter list had a variadic in a non-trailing position, don't expand it
             const parameters = (some(expandedParams, p => p !== expandedParams[expandedParams.length - 1] && !!(getCheckFlags(p) & CheckFlags.RestParameter)) ? signature.parameters : expandedParams).map(parameter => symbolToParameterDeclaration(parameter, context, kind === SyntaxKind.Constructor));
@@ -7337,7 +7352,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             if (thisParameter) {
                 parameters.unshift(thisParameter);
             }
-            context.flags = flags;
+            restoreFlags();
 
             const returnTypeNode = serializeReturnTypeForSignature(context, signature);
 
@@ -7576,13 +7591,13 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
 
         function typeParameterToDeclarationWithConstraint(type: TypeParameter, context: NodeBuilderContext, constraintNode: TypeNode | undefined): TypeParameterDeclaration {
-            const savedContextFlags = context.flags;
+            const restoreFlags = saveRestoreFlags(context);
             context.flags &= ~NodeBuilderFlags.WriteTypeParametersInQualifiedName; // Avoids potential infinite loop when building for a claimspace with a generic
             const modifiers = factory.createModifiersFromModifierFlags(getTypeParameterModifiers(type));
             const name = typeParameterToName(type, context);
             const defaultParameter = getDefaultFromTypeParameter(type);
             const defaultParameterNode = defaultParameter && typeToTypeNodeHelper(defaultParameter, context);
-            context.flags = savedContextFlags;
+            restoreFlags();
             return factory.createTypeParameterDeclaration(modifiers, name, constraintNode, defaultParameterNode);
         }
 
@@ -7691,7 +7706,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             // Try to get qualified name if the symbol is not a type parameter and there is an enclosing declaration.
             let chain: Symbol[];
             const isTypeParameter = symbol.flags & SymbolFlags.TypeParameter;
-            if (!isTypeParameter && (context.enclosingDeclaration || context.flags & NodeBuilderFlags.UseFullyQualifiedType) && !(context.flags & NodeBuilderFlags.DoNotIncludeSymbolChain)) {
+            if (!isTypeParameter && (context.enclosingDeclaration || context.flags & NodeBuilderFlags.UseFullyQualifiedType) && !(context.internalFlags & InternalNodeBuilderFlags.DoNotIncludeSymbolChain)) {
                 chain = Debug.checkDefined(getSymbolChain(symbol, meaning, /*endOfChain*/ true));
                 Debug.assert(chain && chain.length > 0);
             }
@@ -8303,12 +8318,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         function serializeTypeForDeclaration(context: NodeBuilderContext, declaration: Declaration | undefined, type: Type, symbol: Symbol) {
             const addUndefinedForParameter = declaration && (isParameter(declaration) || isJSDocParameterTag(declaration)) && requiresAddingImplicitUndefined(declaration);
             const enclosingDeclaration = context.enclosingDeclaration;
-            const oldFlags = context.flags;
-            if (declaration && hasInferredType(declaration) && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) {
+            const restoreFlags = saveRestoreFlags(context);
+            if (declaration && hasInferredType(declaration) && !(context.internalFlags & InternalNodeBuilderFlags.NoSyntacticPrinter)) {
                 syntacticNodeBuilder.serializeTypeOfDeclaration(declaration, context);
             }
-            context.flags |= NodeBuilderFlags.NoSyntacticPrinter;
-            if (enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames))) {
+            context.internalFlags |= InternalNodeBuilderFlags.NoSyntacticPrinter;
+            if (enclosingDeclaration && (!isErrorType(type) || (context.internalFlags & InternalNodeBuilderFlags.AllowUnresolvedNames))) {
                 const declWithExistingAnnotation = declaration && getNonlocalEffectiveTypeAnnotationNode(declaration)
                     ? declaration
                     : getDeclarationWithTypeAnnotation(symbol);
@@ -8319,7 +8334,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     const addUndefined = addUndefinedForParameter || !!(symbol.flags & SymbolFlags.Property && symbol.flags & SymbolFlags.Optional && isOptionalDeclaration(declWithExistingAnnotation) && (symbol as MappedSymbol).links?.mappedType && containsNonMissingUndefinedType(type));
                     const result = !isTypePredicateNode(existing) && tryReuseExistingTypeNode(context, existing, type, declWithExistingAnnotation, addUndefined);
                     if (result) {
-                        context.flags = oldFlags;
+                        restoreFlags();
                         return result;
                     }
                 }
@@ -8335,7 +8350,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             const expr = decl && isDeclarationWithPossibleInnerTypeNodeReuse(decl) ? getPossibleTypeNodeReuseExpression(decl) : undefined;
 
             const result = expressionOrTypeToTypeNode(context, expr, type, addUndefinedForParameter);
-            context.flags = oldFlags;
+            restoreFlags();
             return result;
         }
 
@@ -8351,28 +8366,28 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
         function serializeReturnTypeForSignature(context: NodeBuilderContext, signature: Signature) {
             const suppressAny = context.flags & NodeBuilderFlags.SuppressAnyReturnType;
-            const flags = context.flags;
+            const restoreFlags = saveRestoreFlags(context);
             if (suppressAny) context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // suppress only toplevel `any`s
             let returnTypeNode: TypeNode | undefined;
             const returnType = getReturnTypeOfSignature(signature);
             if (returnType && !(suppressAny && isTypeAny(returnType))) {
-                if (signature.declaration && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) {
+                if (signature.declaration && !(context.internalFlags & InternalNodeBuilderFlags.NoSyntacticPrinter)) {
                     syntacticNodeBuilder.serializeReturnTypeForSignature(signature.declaration, context);
                 }
-                context.flags |= NodeBuilderFlags.NoSyntacticPrinter;
+                context.internalFlags |= InternalNodeBuilderFlags.NoSyntacticPrinter;
                 returnTypeNode = serializeReturnTypeForSignatureWorker(context, signature);
             }
             else if (!suppressAny) {
                 returnTypeNode = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword);
             }
-            context.flags = flags;
+            restoreFlags();
             return returnTypeNode;
         }
 
         function serializeReturnTypeForSignatureWorker(context: NodeBuilderContext, signature: Signature) {
             const typePredicate = getTypePredicateOfSignature(signature);
             const type = getReturnTypeOfSignature(signature);
-            if (context.enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames)) && signature.declaration && !nodeIsSynthesized(signature.declaration)) {
+            if (context.enclosingDeclaration && (!isErrorType(type) || (context.internalFlags & InternalNodeBuilderFlags.AllowUnresolvedNames)) && signature.declaration && !nodeIsSynthesized(signature.declaration)) {
                 const annotation = getNonlocalEffectiveReturnTypeAnnotationNode(signature.declaration);
                 if (annotation) {
                     const result = tryReuseExistingTypeNode(context, annotation, type, context.enclosingDeclaration);
@@ -8891,7 +8906,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     if (!hasDynamicName(node)) {
                         return visitEachChild(node, visitExistingNodeTreeSymbols);
                     }
-                    if (!(context.flags & NodeBuilderFlags.AllowUnresolvedNames && isEntityNameExpression(node.name.expression) && checkComputedPropertyName(node.name).flags & TypeFlags.Any)) {
+                    if (!(context.internalFlags & InternalNodeBuilderFlags.AllowUnresolvedNames && isEntityNameExpression(node.name.expression) && checkComputedPropertyName(node.name).flags & TypeFlags.Any)) {
                         return undefined;
                     }
                 }
@@ -9623,7 +9638,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 const typeParamDecls = map(typeParams, p => typeParameterToDeclaration(p, context));
                 const jsdocAliasDecl = symbol.declarations?.find(isJSDocTypeAlias);
                 const commentText = getTextOfJSDocComment(jsdocAliasDecl ? jsdocAliasDecl.comment || jsdocAliasDecl.parent.comment : undefined);
-                const oldFlags = context.flags;
+                const restoreFlags = saveRestoreFlags(context);
                 context.flags |= NodeBuilderFlags.InTypeAlias;
                 const oldEnclosingDecl = context.enclosingDeclaration;
                 context.enclosingDeclaration = jsdocAliasDecl;
@@ -9638,7 +9653,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     ),
                     modifierFlags,
                 );
-                context.flags = oldFlags;
+                restoreFlags();
                 context.enclosingDeclaration = oldEnclosingDecl;
             }
 
@@ -10651,10 +10666,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
             function getNameCandidateWorker(symbol: Symbol, localName: string) {
                 if (localName === InternalSymbolName.Default || localName === InternalSymbolName.Class || localName === InternalSymbolName.Function) {
-                    const flags = context.flags;
+                    const restoreFlags = saveRestoreFlags(context);
                     context.flags |= NodeBuilderFlags.InInitialEntityName;
                     const nameCandidate = getNameOfSymbolAsWritten(symbol, context);
-                    context.flags = flags;
+                    restoreFlags();
                     localName = nameCandidate.length > 0 && isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? stripQuotes(nameCandidate) : nameCandidate;
                 }
                 if (localName === InternalSymbolName.Default) {
@@ -49879,7 +49894,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
     }
 
-    function createTypeOfDeclaration(declarationIn: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) {
+    function createTypeOfDeclaration(declarationIn: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, internalFlags: InternalNodeBuilderFlags, tracker: SymbolTracker) {
         const declaration = getParseTreeNode(declarationIn, isVariableLikeOrAccessor);
         if (!declaration) {
             return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode;
@@ -49890,7 +49905,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             ? getWidenedLiteralType(getTypeOfSymbol(symbol))
             : errorType;
 
-        return nodeBuilder.serializeTypeForDeclaration(declaration, type, symbol, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker);
+        return nodeBuilder.serializeTypeForDeclaration(declaration, type, symbol, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, internalFlags, tracker);
     }
 
     type DeclarationWithPotentialInnerNodeReuse =
@@ -49956,21 +49971,21 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         return candidateExpr;
     }
 
-    function createReturnTypeOfSignatureDeclaration(signatureDeclarationIn: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) {
+    function createReturnTypeOfSignatureDeclaration(signatureDeclarationIn: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, internalFlags: InternalNodeBuilderFlags, tracker: SymbolTracker) {
         const signatureDeclaration = getParseTreeNode(signatureDeclarationIn, isFunctionLike);
         if (!signatureDeclaration) {
             return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode;
         }
-        return nodeBuilder.serializeReturnTypeForSignature(getSignatureFromDeclaration(signatureDeclaration), enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker);
+        return nodeBuilder.serializeReturnTypeForSignature(getSignatureFromDeclaration(signatureDeclaration), enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, internalFlags, tracker);
     }
 
-    function createTypeOfExpression(exprIn: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) {
+    function createTypeOfExpression(exprIn: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, internalFlags: InternalNodeBuilderFlags, tracker: SymbolTracker) {
         const expr = getParseTreeNode(exprIn, isExpression);
         if (!expr) {
             return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode;
         }
         const type = getWidenedType(getRegularTypeOfExpression(expr));
-        return nodeBuilder.expressionOrTypeToTypeNode(expr, type, /*addUndefined*/ undefined, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker);
+        return nodeBuilder.expressionOrTypeToTypeNode(expr, type, /*addUndefined*/ undefined, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, internalFlags, tracker);
     }
 
     function hasGlobalName(name: string): boolean {
@@ -50078,7 +50093,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     }
 
     function literalTypeToNode(type: FreshableType, enclosing: Node, tracker: SymbolTracker): Expression {
-        const enumResult = type.flags & TypeFlags.EnumLike ? nodeBuilder.symbolToExpression(type.symbol, SymbolFlags.Value, enclosing, /*flags*/ undefined, tracker)
+        const enumResult = type.flags & TypeFlags.EnumLike ? nodeBuilder.symbolToExpression(type.symbol, SymbolFlags.Value, enclosing, /*flags*/ undefined, /*internalFlags*/ undefined, tracker)
             : type === trueType ? factory.createTrue() : type === falseType && factory.createFalse();
         if (enumResult) return enumResult;
         const literalValue = (type as LiteralType).value;
@@ -50218,15 +50233,15 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 const parseDecl = getParseTreeNode(decl);
                 return !!parseNode && !!parseDecl && (isVariableDeclaration(parseDecl) || isBindingElement(parseDecl)) && isBindingCapturedByNode(parseNode, parseDecl);
             },
-            getDeclarationStatementsForSourceFile: (node, flags, tracker) => {
+            getDeclarationStatementsForSourceFile: (node, flags, internalFlags, tracker) => {
                 const n = getParseTreeNode(node) as SourceFile;
                 Debug.assert(n && n.kind === SyntaxKind.SourceFile, "Non-sourcefile node passed into getDeclarationsForSourceFile");
                 const sym = getSymbolOfDeclaration(node);
                 if (!sym) {
-                    return !node.locals ? [] : nodeBuilder.symbolTableToDeclarationStatements(node.locals, node, flags, tracker);
+                    return !node.locals ? [] : nodeBuilder.symbolTableToDeclarationStatements(node.locals, node, flags, internalFlags, tracker);
                 }
                 resolveExternalModuleSymbol(sym); // ensures cjs export assignment is setup
-                return !sym.exports ? [] : nodeBuilder.symbolTableToDeclarationStatements(sym.exports, node, flags, tracker);
+                return !sym.exports ? [] : nodeBuilder.symbolTableToDeclarationStatements(sym.exports, node, flags, internalFlags, tracker);
             },
             isImportRequiredByAugmentation,
             isDefinitelyReferenceToGlobalSymbolObject,
@@ -52553,6 +52568,7 @@ interface NodeBuilderContext {
      */
     enclosingFile: SourceFile | undefined;
     flags: NodeBuilderFlags;
+    internalFlags: InternalNodeBuilderFlags;
     tracker: SymbolTrackerImpl;
 
     // State
diff --git a/src/compiler/transformers/declarations.ts b/src/compiler/transformers/declarations.ts
index 166431a745069..536e0cf5d9c22 100644
--- a/src/compiler/transformers/declarations.ts
+++ b/src/compiler/transformers/declarations.ts
@@ -87,6 +87,7 @@ import {
     ImportTypeNode,
     IndexSignatureDeclaration,
     InterfaceDeclaration,
+    InternalNodeBuilderFlags,
     isAmbientModule,
     isArray,
     isArrayBindingElement,
@@ -239,10 +240,11 @@ const declarationEmitNodeBuilderFlags = NodeBuilderFlags.MultilineObjectLiterals
     NodeBuilderFlags.UseTypeOfFunction |
     NodeBuilderFlags.UseStructuralFallback |
     NodeBuilderFlags.AllowEmptyTuple |
-    NodeBuilderFlags.AllowUnresolvedNames |
     NodeBuilderFlags.GenerateNamesForShadowedTypeParams |
     NodeBuilderFlags.NoTruncation;
 
+const declarationEmitInternalNodeBuilderFlags = InternalNodeBuilderFlags.AllowUnresolvedNames;
+
 /**
  * Transforms a ts file into a .d.ts file
  * This process requires type information, which is retrieved through the emit resolver. Because of this,
@@ -429,7 +431,7 @@ export function transformDeclarations(context: TransformationContext) {
                 : Diagnostics.Declaration_emit_for_this_file_requires_using_private_name_0_An_explicit_type_annotation_may_unblock_declaration_emit,
             errorNode: s.errorNode || sourceFile,
         }));
-        const result = resolver.getDeclarationStatementsForSourceFile(sourceFile, declarationEmitNodeBuilderFlags, symbolTracker);
+        const result = resolver.getDeclarationStatementsForSourceFile(sourceFile, declarationEmitNodeBuilderFlags, declarationEmitInternalNodeBuilderFlags, symbolTracker);
         getSymbolAccessibilityDiagnostic = oldDiag;
         return result;
     }
@@ -696,7 +698,7 @@ export function transformDeclarations(context: TransformationContext) {
             case SyntaxKind.PropertyDeclaration:
             case SyntaxKind.BindingElement:
             case SyntaxKind.VariableDeclaration:
-                typeNode = resolver.createTypeOfDeclaration(node, enclosingDeclaration, declarationEmitNodeBuilderFlags, symbolTracker);
+                typeNode = resolver.createTypeOfDeclaration(node, enclosingDeclaration, declarationEmitNodeBuilderFlags, declarationEmitInternalNodeBuilderFlags, symbolTracker);
                 break;
             case SyntaxKind.FunctionDeclaration:
             case SyntaxKind.ConstructSignature:
@@ -704,7 +706,7 @@ export function transformDeclarations(context: TransformationContext) {
             case SyntaxKind.MethodDeclaration:
             case SyntaxKind.GetAccessor:
             case SyntaxKind.CallSignature:
-                typeNode = resolver.createReturnTypeOfSignatureDeclaration(node, enclosingDeclaration, declarationEmitNodeBuilderFlags, symbolTracker);
+                typeNode = resolver.createReturnTypeOfSignatureDeclaration(node, enclosingDeclaration, declarationEmitNodeBuilderFlags, declarationEmitInternalNodeBuilderFlags, symbolTracker);
                 break;
             default:
                 Debug.assertNever(node);
@@ -1329,7 +1331,7 @@ export function transformDeclarations(context: TransformationContext) {
                         errorNode: input,
                     });
                     errorFallbackNode = input;
-                    const varDecl = factory.createVariableDeclaration(newId, /*exclamationToken*/ undefined, resolver.createTypeOfExpression(input.expression, input, declarationEmitNodeBuilderFlags, symbolTracker), /*initializer*/ undefined);
+                    const varDecl = factory.createVariableDeclaration(newId, /*exclamationToken*/ undefined, resolver.createTypeOfExpression(input.expression, input, declarationEmitNodeBuilderFlags, declarationEmitInternalNodeBuilderFlags, symbolTracker), /*initializer*/ undefined);
                     errorFallbackNode = undefined;
                     const statement = factory.createVariableStatement(needsDeclare ? [factory.createModifier(SyntaxKind.DeclareKeyword)] : [], factory.createVariableDeclarationList([varDecl], NodeFlags.Const));
 
@@ -1471,7 +1473,7 @@ export function transformDeclarations(context: TransformationContext) {
                             return undefined; // unique symbol or non-identifier name - omit, since there's no syntax that can preserve it
                         }
                         getSymbolAccessibilityDiagnostic = createGetSymbolAccessibilityDiagnosticForNode(p.valueDeclaration);
-                        const type = resolver.createTypeOfDeclaration(p.valueDeclaration, fakespace, declarationEmitNodeBuilderFlags | NodeBuilderFlags.NoSyntacticPrinter, symbolTracker);
+                        const type = resolver.createTypeOfDeclaration(p.valueDeclaration, fakespace, declarationEmitNodeBuilderFlags, declarationEmitInternalNodeBuilderFlags | InternalNodeBuilderFlags.NoSyntacticPrinter, symbolTracker);
                         getSymbolAccessibilityDiagnostic = oldDiag;
                         const isNonContextualKeywordName = isStringANonContextualKeyword(nameStr);
                         const name = isNonContextualKeywordName ? factory.getGeneratedNameForNode(p.valueDeclaration) : factory.createIdentifier(nameStr);
@@ -1666,7 +1668,7 @@ export function transformDeclarations(context: TransformationContext) {
                         errorNode: extendsClause,
                         typeName: input.name,
                     });
-                    const varDecl = factory.createVariableDeclaration(newId, /*exclamationToken*/ undefined, resolver.createTypeOfExpression(extendsClause.expression, input, declarationEmitNodeBuilderFlags, symbolTracker), /*initializer*/ undefined);
+                    const varDecl = factory.createVariableDeclaration(newId, /*exclamationToken*/ undefined, resolver.createTypeOfExpression(extendsClause.expression, input, declarationEmitNodeBuilderFlags, declarationEmitInternalNodeBuilderFlags, symbolTracker), /*initializer*/ undefined);
                     const statement = factory.createVariableStatement(needsDeclare ? [factory.createModifier(SyntaxKind.DeclareKeyword)] : [], factory.createVariableDeclarationList([varDecl], NodeFlags.Const));
                     const heritageClauses = factory.createNodeArray(map(input.heritageClauses, clause => {
                         if (clause.token === SyntaxKind.ExtendsKeyword) {
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 9b0ab54b0aa0e..3f5306cec0383 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -5073,14 +5073,14 @@ export interface TypeChecker {
     // TODO: GH#18217 `xToDeclaration` calls are frequently asserted as defined.
     /** Note that the resulting nodes cannot be checked. */
     typeToTypeNode(type: Type, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined): TypeNode | undefined;
-    /** @internal */ typeToTypeNode(type: Type, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker?: SymbolTracker): TypeNode | undefined; // eslint-disable-line @typescript-eslint/unified-signatures
-    /** @internal */ typePredicateToTypePredicateNode(typePredicate: TypePredicate, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker?: SymbolTracker): TypePredicateNode | undefined;
+    /** @internal */ typeToTypeNode(type: Type, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, internalFlags?: InternalNodeBuilderFlags | undefined, tracker?: SymbolTracker): TypeNode | undefined; // eslint-disable-line @typescript-eslint/unified-signatures
+    /** @internal */ typePredicateToTypePredicateNode(typePredicate: TypePredicate, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, internalFlags?: InternalNodeBuilderFlags | undefined, tracker?: SymbolTracker): TypePredicateNode | undefined;
     /** Note that the resulting nodes cannot be checked. */
     signatureToSignatureDeclaration(signature: Signature, kind: SyntaxKind, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined): SignatureDeclaration & { typeArguments?: NodeArray<TypeNode>; } | undefined;
-    /** @internal */ signatureToSignatureDeclaration(signature: Signature, kind: SyntaxKind, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker?: SymbolTracker): SignatureDeclaration & { typeArguments?: NodeArray<TypeNode>; } | undefined; // eslint-disable-line @typescript-eslint/unified-signatures
+    /** @internal */ signatureToSignatureDeclaration(signature: Signature, kind: SyntaxKind, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, internalFlags?: InternalNodeBuilderFlags | undefined, tracker?: SymbolTracker): SignatureDeclaration & { typeArguments?: NodeArray<TypeNode>; } | undefined; // eslint-disable-line @typescript-eslint/unified-signatures
     /** Note that the resulting nodes cannot be checked. */
     indexInfoToIndexSignatureDeclaration(indexInfo: IndexInfo, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined): IndexSignatureDeclaration | undefined;
-    /** @internal */ indexInfoToIndexSignatureDeclaration(indexInfo: IndexInfo, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker?: SymbolTracker): IndexSignatureDeclaration | undefined; // eslint-disable-line @typescript-eslint/unified-signatures
+    /** @internal */ indexInfoToIndexSignatureDeclaration(indexInfo: IndexInfo, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, internalFlags?: InternalNodeBuilderFlags | undefined, tracker?: SymbolTracker): IndexSignatureDeclaration | undefined; // eslint-disable-line @typescript-eslint/unified-signatures
     /** Note that the resulting nodes cannot be checked. */
     symbolToEntityName(symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined): EntityName | undefined;
     /** Note that the resulting nodes cannot be checked. */
@@ -5090,7 +5090,7 @@ export interface TypeChecker {
      *
      * @internal
      */
-    symbolToNode(symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined): Node | undefined;
+    symbolToNode(symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, internalFlags: InternalNodeBuilderFlags | undefined): Node | undefined;
     /** Note that the resulting nodes cannot be checked. */
     symbolToTypeParameterDeclarations(symbol: Symbol, enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined): NodeArray<TypeParameterDeclaration> | undefined;
     /** Note that the resulting nodes cannot be checked. */
@@ -5459,12 +5459,9 @@ export const enum NodeBuilderFlags {
     AllowEmptyTuple                         = 1 << 19,
     AllowUniqueESSymbolType                 = 1 << 20,
     AllowEmptyIndexInfoType                 = 1 << 21,
-    /** @internal */ WriteComputedProps      = 1 << 30, // { [E.A]: 1 }
-    /** @internal */ NoSyntacticPrinter     = 1 << 31,
     // Errors (cont.)
     AllowNodeModulesRelativePaths           = 1 << 26,
-    /** @internal */ DoNotIncludeSymbolChain = 1 << 27,    // Skip looking up and printing an accessible symbol chain
-    /** @internal */ AllowUnresolvedNames = 1 << 32,
+    
 
     IgnoreErrors = AllowThisInObjectLiteral | AllowQualifiedNameInPlaceOfIdentifier | AllowAnonymousIdentifier | AllowEmptyUnionOrIntersection | AllowEmptyTuple | AllowEmptyIndexInfoType | AllowNodeModulesRelativePaths,
 
@@ -5474,6 +5471,16 @@ export const enum NodeBuilderFlags {
     InInitialEntityName                     = 1 << 24,    // Set when writing the LHS of an entity name or entity name expression
 }
 
+/** @internal */
+// dprint-ignore
+export const enum InternalNodeBuilderFlags {
+    None                                    = 0,
+    WriteComputedProps                      = 1 << 0, // { [E.A]: 1 }
+    NoSyntacticPrinter                      = 1 << 1,
+    DoNotIncludeSymbolChain                 = 1 << 2,    // Skip looking up and printing an accessible symbol chain
+    AllowUnresolvedNames                    = 1 << 3,
+}
+
 // Ensure the shared flags between this and `NodeBuilderFlags` stay in alignment
 // dprint-ignore
 export const enum TypeFormatFlags {
@@ -5810,9 +5817,9 @@ export interface EmitResolver {
     requiresAddingImplicitUndefined(node: ParameterDeclaration): boolean;
     isExpandoFunctionDeclaration(node: FunctionDeclaration | VariableDeclaration): boolean;
     getPropertiesOfContainerFunction(node: Declaration): Symbol[];
-    createTypeOfDeclaration(declaration: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression | ElementAccessExpression | BinaryExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
-    createReturnTypeOfSignatureDeclaration(signatureDeclaration: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
-    createTypeOfExpression(expr: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
+    createTypeOfDeclaration(declaration: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression | ElementAccessExpression | BinaryExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, internalFlags: InternalNodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
+    createReturnTypeOfSignatureDeclaration(signatureDeclaration: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, internalFlags: InternalNodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
+    createTypeOfExpression(expr: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, internalFlags: InternalNodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
     createLiteralConstValue(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration, tracker: SymbolTracker): Expression;
     isSymbolAccessible(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags | undefined, shouldComputeAliasToMarkVisible: boolean): SymbolAccessibilityResult;
     isEntityNameVisible(entityName: EntityNameOrEntityNameExpression, enclosingDeclaration: Node): SymbolVisibilityResult;
@@ -5829,7 +5836,7 @@ export interface EmitResolver {
     getJsxFactoryEntity(location?: Node): EntityName | undefined;
     getJsxFragmentFactoryEntity(location?: Node): EntityName | undefined;
     isBindingCapturedByNode(node: Node, decl: VariableDeclaration | BindingElement): boolean;
-    getDeclarationStatementsForSourceFile(node: SourceFile, flags: NodeBuilderFlags, tracker: SymbolTracker): Statement[] | undefined;
+    getDeclarationStatementsForSourceFile(node: SourceFile, flags: NodeBuilderFlags, internalFlags: InternalNodeBuilderFlags, tracker: SymbolTracker): Statement[] | undefined;
     isImportRequiredByAugmentation(decl: ImportDeclaration): boolean;
     isDefinitelyReferenceToGlobalSymbolObject(node: Node): boolean;
 }
diff --git a/src/harness/typeWriter.ts b/src/harness/typeWriter.ts
index e09f8bd56a272..96bd527077d8e 100644
--- a/src/harness/typeWriter.ts
+++ b/src/harness/typeWriter.ts
@@ -279,7 +279,7 @@ export class TypeWriterWalker {
             }
             else {
                 const typeFormatFlags = ts.TypeFormatFlags.NoTruncation | ts.TypeFormatFlags.AllowUniqueESSymbolType | ts.TypeFormatFlags.GenerateNamesForShadowedTypeParams;
-                let typeNode = this.checker.typeToTypeNode(type, node.parent, (typeFormatFlags & ts.TypeFormatFlags.NodeBuilderFlagsMask) | ts.NodeBuilderFlags.IgnoreErrors)!;
+                let typeNode = this.checker.typeToTypeNode(type, node.parent, (typeFormatFlags & ts.TypeFormatFlags.NodeBuilderFlagsMask) | ts.NodeBuilderFlags.IgnoreErrors, ts.InternalNodeBuilderFlags.AllowUnresolvedNames)!;
                 if (ts.isIdentifier(node) && ts.isTypeAliasDeclaration(node.parent) && node.parent.name === node && ts.isIdentifier(typeNode) && ts.idText(typeNode) === ts.idText(node)) {
                     // for a complex type alias `type T = ...`, showing "T : T" isn't very helpful for type tests. When the type produced is the same as
                     // the name of the type alias, recreate the type string without reusing the alias name
diff --git a/src/services/codefixes/fixAddMissingConstraint.ts b/src/services/codefixes/fixAddMissingConstraint.ts
index fad9a8f003a5c..ba1e7aa0279c2 100644
--- a/src/services/codefixes/fixAddMissingConstraint.ts
+++ b/src/services/codefixes/fixAddMissingConstraint.ts
@@ -123,7 +123,7 @@ function addMissingConstraint(changes: textChanges.ChangeTracker, program: Progr
         const scriptTarget = getEmitScriptTarget(program.getCompilerOptions());
         const tracker = getNoopSymbolTrackerWithResolver({ program, host });
         const importAdder = createImportAdder(sourceFile, program, preferences, host);
-        const typeNode = typeToAutoImportableTypeNode(checker, importAdder, constraint, /*contextNode*/ undefined, scriptTarget, /*flags*/ undefined, tracker);
+        const typeNode = typeToAutoImportableTypeNode(checker, importAdder, constraint, /*contextNode*/ undefined, scriptTarget, /*flags*/ undefined, /*internalFlags*/ undefined, tracker);
         if (typeNode) {
             changes.replaceNode(sourceFile, declaration, factory.updateTypeParameterDeclaration(declaration, /*modifiers*/ undefined, declaration.name, typeNode, declaration.default));
             importAdder.writeFixes(changes);
diff --git a/src/services/codefixes/fixAddMissingMember.ts b/src/services/codefixes/fixAddMissingMember.ts
index 190fba39043c0..77bec1ed7f173 100644
--- a/src/services/codefixes/fixAddMissingMember.ts
+++ b/src/services/codefixes/fixAddMissingMember.ts
@@ -55,6 +55,7 @@ import {
     Identifier,
     idText,
     InterfaceDeclaration,
+    InternalNodeBuilderFlags,
     isCallExpression,
     isClassLike,
     isComputedPropertyName,
@@ -493,11 +494,11 @@ function getTypeNode(checker: TypeChecker, node: ClassLikeDeclaration | Interfac
         const binaryExpression = token.parent.parent as BinaryExpression;
         const otherExpression = token.parent === binaryExpression.left ? binaryExpression.right : binaryExpression.left;
         const widenedType = checker.getWidenedType(checker.getBaseTypeOfLiteralType(checker.getTypeAtLocation(otherExpression)));
-        typeNode = checker.typeToTypeNode(widenedType, node, NodeBuilderFlags.NoTruncation);
+        typeNode = checker.typeToTypeNode(widenedType, node, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames);
     }
     else {
         const contextualType = checker.getContextualType(token.parent as Expression);
-        typeNode = contextualType ? checker.typeToTypeNode(contextualType, /*enclosingDeclaration*/ undefined, NodeBuilderFlags.NoTruncation) : undefined;
+        typeNode = contextualType ? checker.typeToTypeNode(contextualType, /*enclosingDeclaration*/ undefined, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames) : undefined;
     }
     return typeNode || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword);
 }
@@ -775,7 +776,7 @@ function tryGetContainingMethodDeclaration(node: ClassLikeDeclaration | Interfac
 
 function createPropertyNameFromSymbol(symbol: Symbol, target: ScriptTarget, quotePreference: QuotePreference, checker: TypeChecker) {
     if (isTransientSymbol(symbol)) {
-        const prop = checker.symbolToNode(symbol, SymbolFlags.Value, /*enclosingDeclaration*/ undefined, NodeBuilderFlags.WriteComputedProps);
+        const prop = checker.symbolToNode(symbol, SymbolFlags.Value, /*enclosingDeclaration*/ undefined, /*flags*/ undefined, InternalNodeBuilderFlags.WriteComputedProps);
         if (prop && isComputedPropertyName(prop)) return prop;
     }
     // We're using these nodes as property names in an object literal; no need to quote names when not needed.
diff --git a/src/services/codefixes/fixAddMissingParam.ts b/src/services/codefixes/fixAddMissingParam.ts
index c5ac4f25b2b09..65c9cf861586e 100644
--- a/src/services/codefixes/fixAddMissingParam.ts
+++ b/src/services/codefixes/fixAddMissingParam.ts
@@ -26,6 +26,7 @@ import {
     getNameOfDeclaration,
     getSourceFileOfNode,
     getTokenAtPosition,
+    InternalNodeBuilderFlags,
     isAccessExpression,
     isCallExpression,
     isIdentifier,
@@ -221,7 +222,7 @@ function tryGetName(node: FunctionLikeDeclaration) {
 }
 
 function typeToTypeNode(checker: TypeChecker, type: Type, enclosingDeclaration: Node) {
-    return checker.typeToTypeNode(checker.getWidenedType(type), enclosingDeclaration, NodeBuilderFlags.NoTruncation)
+    return checker.typeToTypeNode(checker.getWidenedType(type), enclosingDeclaration, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames)
         ?? factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword);
 }
 
diff --git a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
index d5dacd51dc59d..a0dd5aa5e5899 100644
--- a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
+++ b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
@@ -108,7 +108,7 @@ function addMissingDeclarations(
     function createMissingIndexSignatureDeclaration(type: InterfaceType, kind: IndexKind): void {
         const indexInfoOfKind = checker.getIndexInfoOfType(type, kind);
         if (indexInfoOfKind) {
-            insertInterfaceMemberNode(sourceFile, classDeclaration, checker.indexInfoToIndexSignatureDeclaration(indexInfoOfKind, classDeclaration, /*flags*/ undefined, getNoopSymbolTrackerWithResolver(context))!);
+            insertInterfaceMemberNode(sourceFile, classDeclaration, checker.indexInfoToIndexSignatureDeclaration(indexInfoOfKind, classDeclaration, /*flags*/ undefined, /*internalFlags*/ undefined, getNoopSymbolTrackerWithResolver(context))!);
         }
     }
 
diff --git a/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts b/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts
index deea661f2e72a..0b84557078237 100644
--- a/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts
+++ b/src/services/codefixes/fixMissingTypeAnnotationOnExports.ts
@@ -45,6 +45,7 @@ import {
     hasInitializer,
     hasSyntacticModifier,
     Identifier,
+    InternalNodeBuilderFlags,
     isArrayBindingPattern,
     isArrayLiteralExpression,
     isAssertionExpression,
@@ -159,8 +160,9 @@ const declarationEmitNodeBuilderFlags = NodeBuilderFlags.MultilineObjectLiterals
     | NodeBuilderFlags.UseStructuralFallback
     | NodeBuilderFlags.AllowEmptyTuple
     | NodeBuilderFlags.GenerateNamesForShadowedTypeParams
-    | NodeBuilderFlags.NoTruncation
-    | NodeBuilderFlags.WriteComputedProps;
+    | NodeBuilderFlags.NoTruncation;
+
+const declarationEmitInternalNodeBuilderFlags = InternalNodeBuilderFlags.WriteComputedProps;
 
 enum TypePrintMode {
     // Prints its fully spelled out type
@@ -1095,7 +1097,7 @@ function withContext<T>(
 
     function typeToTypeNode(type: Type, enclosingDeclaration: Node, flags = NodeBuilderFlags.None) {
         let isTruncated = false;
-        const result = typeToAutoImportableTypeNode(typeChecker, importAdder, type, enclosingDeclaration, scriptTarget, declarationEmitNodeBuilderFlags | flags, {
+        const result = typeToAutoImportableTypeNode(typeChecker, importAdder, type, enclosingDeclaration, scriptTarget, declarationEmitNodeBuilderFlags | flags, declarationEmitInternalNodeBuilderFlags, {
             moduleResolverHost: program,
             trackSymbol() {
                 return true;
@@ -1109,7 +1111,7 @@ function withContext<T>(
 
     function typePredicateToTypeNode(typePredicate: TypePredicate, enclosingDeclaration: Node, flags = NodeBuilderFlags.None): TypeNode | undefined {
         let isTruncated = false;
-        const result = typePredicateToAutoImportableTypeNode(typeChecker, importAdder, typePredicate, enclosingDeclaration, scriptTarget, declarationEmitNodeBuilderFlags | flags, {
+        const result = typePredicateToAutoImportableTypeNode(typeChecker, importAdder, typePredicate, enclosingDeclaration, scriptTarget, declarationEmitNodeBuilderFlags | flags, declarationEmitInternalNodeBuilderFlags, {
             moduleResolverHost: program,
             trackSymbol() {
                 return true;
diff --git a/src/services/codefixes/helpers.ts b/src/services/codefixes/helpers.ts
index 0524080520582..f4a29c3751d12 100644
--- a/src/services/codefixes/helpers.ts
+++ b/src/services/codefixes/helpers.ts
@@ -41,6 +41,7 @@ import {
     hasAbstractModifier,
     Identifier,
     idText,
+    InternalNodeBuilderFlags,
     IntersectionType,
     isArrowFunction,
     isAutoAccessorPropertyDeclaration,
@@ -222,7 +223,7 @@ export function addNewNodeForMemberSymbol(
         case SyntaxKind.PropertyDeclaration:
             let flags = NodeBuilderFlags.NoTruncation;
             flags |= quotePreference === QuotePreference.Single ? NodeBuilderFlags.UseSingleQuotesForStringLiteralType : 0;
-            let typeNode = checker.typeToTypeNode(type, enclosingDeclaration, flags, getNoopSymbolTrackerWithResolver(context));
+            let typeNode = checker.typeToTypeNode(type, enclosingDeclaration, flags, InternalNodeBuilderFlags.AllowUnresolvedNames, getNoopSymbolTrackerWithResolver(context));
             if (importAdder) {
                 const importableReference = tryGetAutoImportableReferenceFromTypeNode(typeNode, scriptTarget);
                 if (importableReference) {
@@ -241,7 +242,7 @@ export function addNewNodeForMemberSymbol(
         case SyntaxKind.GetAccessor:
         case SyntaxKind.SetAccessor: {
             Debug.assertIsDefined(declarations);
-            let typeNode = checker.typeToTypeNode(type, enclosingDeclaration, /*flags*/ undefined, getNoopSymbolTrackerWithResolver(context));
+            let typeNode = checker.typeToTypeNode(type, enclosingDeclaration, /*flags*/ undefined, /*internalFlags*/ undefined, getNoopSymbolTrackerWithResolver(context));
             const allAccessors = getAllAccessorDeclarations(declarations, declaration as AccessorDeclaration);
             const orderedAccessors = allAccessors.secondAccessor
                 ? [allAccessors.firstAccessor, allAccessors.secondAccessor]
@@ -392,7 +393,7 @@ export function createSignatureDeclarationFromSignature(
         | NodeBuilderFlags.SuppressAnyReturnType
         | NodeBuilderFlags.AllowEmptyTuple
         | (quotePreference === QuotePreference.Single ? NodeBuilderFlags.UseSingleQuotesForStringLiteralType : NodeBuilderFlags.None);
-    const signatureDeclaration = checker.signatureToSignatureDeclaration(signature, kind, enclosingDeclaration, flags, getNoopSymbolTrackerWithResolver(context)) as ArrowFunction | FunctionExpression | MethodDeclaration | FunctionDeclaration;
+    const signatureDeclaration = checker.signatureToSignatureDeclaration(signature, kind, enclosingDeclaration, flags, InternalNodeBuilderFlags.AllowUnresolvedNames, getNoopSymbolTrackerWithResolver(context)) as ArrowFunction | FunctionExpression | MethodDeclaration | FunctionDeclaration;
     if (!signatureDeclaration) {
         return undefined;
     }
@@ -506,6 +507,7 @@ export function createSignatureDeclarationFromCallExpression(
         contextNode,
         scriptTarget,
         NodeBuilderFlags.NoTruncation,
+        InternalNodeBuilderFlags.AllowUnresolvedNames,
         tracker,
     );
 
@@ -519,7 +521,7 @@ export function createSignatureDeclarationFromCallExpression(
     const parameters = createDummyParameters(args.length, names, argumentTypeNodes, /*minArgumentCount*/ undefined, isJs);
     const type = isJs || contextualType === undefined
         ? undefined
-        : checker.typeToTypeNode(contextualType, contextNode, /*flags*/ undefined, tracker);
+        : checker.typeToTypeNode(contextualType, contextNode, /*flags*/ undefined, /*internalFlags*/ undefined, tracker);
 
     switch (kind) {
         case SyntaxKind.MethodDeclaration:
@@ -589,8 +591,8 @@ function createTypeParameterName(index: number) {
 }
 
 /** @internal */
-export function typeToAutoImportableTypeNode(checker: TypeChecker, importAdder: ImportAdder, type: Type, contextNode: Node | undefined, scriptTarget: ScriptTarget, flags?: NodeBuilderFlags, tracker?: SymbolTracker): TypeNode | undefined {
-    let typeNode = checker.typeToTypeNode(type, contextNode, flags, tracker);
+export function typeToAutoImportableTypeNode(checker: TypeChecker, importAdder: ImportAdder, type: Type, contextNode: Node | undefined, scriptTarget: ScriptTarget, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker): TypeNode | undefined {
+    let typeNode = checker.typeToTypeNode(type, contextNode, flags, internalFlags, tracker);
     if (typeNode && isImportTypeNode(typeNode)) {
         const importableReference = tryGetAutoImportableReferenceFromTypeNode(typeNode, scriptTarget);
         if (importableReference) {
@@ -604,8 +606,8 @@ export function typeToAutoImportableTypeNode(checker: TypeChecker, importAdder:
 }
 
 /** @internal */
-export function typePredicateToAutoImportableTypeNode(checker: TypeChecker, importAdder: ImportAdder, typePredicate: TypePredicate, contextNode: Node | undefined, scriptTarget: ScriptTarget, flags?: NodeBuilderFlags, tracker?: SymbolTracker): TypeNode | undefined {
-    let typePredicateNode = checker.typePredicateToTypePredicateNode(typePredicate, contextNode, flags, tracker);
+export function typePredicateToAutoImportableTypeNode(checker: TypeChecker, importAdder: ImportAdder, typePredicate: TypePredicate, contextNode: Node | undefined, scriptTarget: ScriptTarget, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker): TypeNode | undefined {
+    let typePredicateNode = checker.typePredicateToTypePredicateNode(typePredicate, contextNode, flags, internalFlags, tracker);
     if (typePredicateNode?.type && isImportTypeNode(typePredicateNode.type)) {
         const importableReference = tryGetAutoImportableReferenceFromTypeNode(typePredicateNode.type, scriptTarget);
         if (importableReference) {
@@ -625,7 +627,7 @@ function typeContainsTypeParameter(type: Type) {
     return type.flags & TypeFlags.TypeParameter;
 }
 
-function getArgumentTypesAndTypeParameters(checker: TypeChecker, importAdder: ImportAdder, instanceTypes: Type[], contextNode: Node | undefined, scriptTarget: ScriptTarget, flags?: NodeBuilderFlags, tracker?: SymbolTracker) {
+function getArgumentTypesAndTypeParameters(checker: TypeChecker, importAdder: ImportAdder, instanceTypes: Type[], contextNode: Node | undefined, scriptTarget: ScriptTarget, flags?: NodeBuilderFlags, internalFlags?: InternalNodeBuilderFlags, tracker?: SymbolTracker) {
     // Types to be used as the types of the parameters in the new function
     // E.g. from this source:
     //   added("", 0)
@@ -668,7 +670,7 @@ function getArgumentTypesAndTypeParameters(checker: TypeChecker, importAdder: Im
 
         // Widen the type so we don't emit nonsense annotations like "function fn(x: 3) {"
         const widenedInstanceType = checker.getBaseTypeOfLiteralType(instanceType);
-        const argumentTypeNode = typeToAutoImportableTypeNode(checker, importAdder, widenedInstanceType, contextNode, scriptTarget, flags, tracker);
+        const argumentTypeNode = typeToAutoImportableTypeNode(checker, importAdder, widenedInstanceType, contextNode, scriptTarget, flags, internalFlags, tracker);
         if (!argumentTypeNode) {
             continue;
         }
@@ -686,7 +688,7 @@ function getArgumentTypesAndTypeParameters(checker: TypeChecker, importAdder: Im
         // We instead want to output:
         //    function added<T extends string>(value: T) { ... }
         const instanceTypeConstraint = instanceType.isTypeParameter() && instanceType.constraint && !isAnonymousObjectConstraintType(instanceType.constraint)
-            ? typeToAutoImportableTypeNode(checker, importAdder, instanceType.constraint, contextNode, scriptTarget, flags, tracker)
+            ? typeToAutoImportableTypeNode(checker, importAdder, instanceType.constraint, contextNode, scriptTarget, flags, internalFlags, tracker)
             : undefined;
 
         if (argumentTypeParameter) {
@@ -795,7 +797,7 @@ function createMethodImplementingSignatures(
 function getReturnTypeFromSignatures(signatures: readonly Signature[], checker: TypeChecker, context: TypeConstructionContext, enclosingDeclaration: ClassLikeDeclaration): TypeNode | undefined {
     if (length(signatures)) {
         const type = checker.getUnionType(map(signatures, checker.getReturnTypeOfSignature));
-        return checker.typeToTypeNode(type, enclosingDeclaration, NodeBuilderFlags.NoTruncation, getNoopSymbolTrackerWithResolver(context));
+        return checker.typeToTypeNode(type, enclosingDeclaration, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames, getNoopSymbolTrackerWithResolver(context));
     }
 }
 
diff --git a/src/services/completions.ts b/src/services/completions.ts
index 1300005c8b570..ee67c03331563 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -2324,7 +2324,7 @@ function createObjectLiteralMethod(
                 // We don't support overloads in object literals.
                 return undefined;
             }
-            const typeNode = checker.typeToTypeNode(effectiveType, enclosingDeclaration, builderFlags, codefix.getNoopSymbolTrackerWithResolver({ program, host }));
+            const typeNode = checker.typeToTypeNode(effectiveType, enclosingDeclaration, builderFlags, /*internalFlags*/ undefined, codefix.getNoopSymbolTrackerWithResolver({ program, host }));
             if (!typeNode || !isFunctionTypeNode(typeNode)) {
                 return undefined;
             }
diff --git a/src/services/refactors/extractSymbol.ts b/src/services/refactors/extractSymbol.ts
index d5ebc4e3c040d..4093074b9575a 100644
--- a/src/services/refactors/extractSymbol.ts
+++ b/src/services/refactors/extractSymbol.ts
@@ -61,6 +61,7 @@ import {
     hasEffectiveModifier,
     hasSyntacticModifier,
     Identifier,
+    InternalNodeBuilderFlags,
     isArray,
     isArrowFunction,
     isAssignmentExpression,
@@ -1062,7 +1063,7 @@ function extractFunctionInScope(
             let type = checker.getTypeOfSymbolAtLocation(usage.symbol, usage.node);
             // Widen the type so we don't emit nonsense annotations like "function fn(x: 3) {"
             type = checker.getBaseTypeOfLiteralType(type);
-            typeNode = codefix.typeToAutoImportableTypeNode(checker, importAdder, type, scope, scriptTarget, NodeBuilderFlags.NoTruncation);
+            typeNode = codefix.typeToAutoImportableTypeNode(checker, importAdder, type, scope, scriptTarget, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames);
         }
 
         const paramDecl = factory.createParameterDeclaration(
@@ -1096,7 +1097,7 @@ function extractFunctionInScope(
     // to avoid problems when there are literal types present
     if (isExpression(node) && !isJS) {
         const contextualType = checker.getContextualType(node);
-        returnType = checker.typeToTypeNode(contextualType!, scope, NodeBuilderFlags.NoTruncation); // TODO: GH#18217
+        returnType = checker.typeToTypeNode(contextualType!, scope, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames); // TODO: GH#18217
     }
 
     const { body, returnValueProperty } = transformFunctionBody(node, exposedVariableDeclarations, writes, substitutions, !!(range.facts & RangeFacts.HasReturn));
@@ -1138,6 +1139,7 @@ function extractFunctionInScope(
                         checker.getTypeAtLocation(range.thisNode!),
                         scope,
                         NodeBuilderFlags.NoTruncation,
+                        InternalNodeBuilderFlags.AllowUnresolvedNames,
                     ),
                     /*initializer*/ undefined,
                 ),
@@ -1228,6 +1230,7 @@ function extractFunctionInScope(
                     checker.getBaseTypeOfLiteralType(checker.getTypeAtLocation(variableDeclaration)),
                     scope,
                     NodeBuilderFlags.NoTruncation,
+                    InternalNodeBuilderFlags.AllowUnresolvedNames,
                 );
 
                 typeElements.push(factory.createPropertySignature(
@@ -1378,7 +1381,7 @@ function extractConstantInScope(
 
     let variableType = isJS || !checker.isContextSensitive(node)
         ? undefined
-        : checker.typeToTypeNode(checker.getContextualType(node)!, scope, NodeBuilderFlags.NoTruncation); // TODO: GH#18217
+        : checker.typeToTypeNode(checker.getContextualType(node)!, scope, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames); // TODO: GH#18217
 
     let initializer = transformConstantInitializer(skipParentheses(node), substitutions);
 
@@ -1512,7 +1515,7 @@ function extractConstantInScope(
                 const paramType = checker.getTypeAtLocation(p);
                 if (paramType === checker.getAnyType()) hasAny = true;
 
-                parameters.push(factory.updateParameterDeclaration(p, p.modifiers, p.dotDotDotToken, p.name, p.questionToken, p.type || checker.typeToTypeNode(paramType, scope, NodeBuilderFlags.NoTruncation), p.initializer));
+                parameters.push(factory.updateParameterDeclaration(p, p.modifiers, p.dotDotDotToken, p.name, p.questionToken, p.type || checker.typeToTypeNode(paramType, scope, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames), p.initializer));
             }
         }
         // If a parameter was inferred as any we skip adding function parameters at all.
@@ -1521,7 +1524,7 @@ function extractConstantInScope(
         if (hasAny) return { variableType, initializer };
         variableType = undefined;
         if (isArrowFunction(initializer)) {
-            initializer = factory.updateArrowFunction(initializer, canHaveModifiers(node) ? getModifiers(node) : undefined, initializer.typeParameters, parameters, initializer.type || checker.typeToTypeNode(functionSignature.getReturnType(), scope, NodeBuilderFlags.NoTruncation), initializer.equalsGreaterThanToken, initializer.body);
+            initializer = factory.updateArrowFunction(initializer, canHaveModifiers(node) ? getModifiers(node) : undefined, initializer.typeParameters, parameters, initializer.type || checker.typeToTypeNode(functionSignature.getReturnType(), scope, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames), initializer.equalsGreaterThanToken, initializer.body);
         }
         else {
             if (functionSignature && !!functionSignature.thisParameter) {
@@ -1538,7 +1541,7 @@ function extractConstantInScope(
                             /*dotDotDotToken*/ undefined,
                             "this",
                             /*questionToken*/ undefined,
-                            checker.typeToTypeNode(thisType, scope, NodeBuilderFlags.NoTruncation),
+                            checker.typeToTypeNode(thisType, scope, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames),
                         ),
                     );
                 }
diff --git a/src/services/refactors/inferFunctionReturnType.ts b/src/services/refactors/inferFunctionReturnType.ts
index 42607e3888bda..d147fbbed19b9 100644
--- a/src/services/refactors/inferFunctionReturnType.ts
+++ b/src/services/refactors/inferFunctionReturnType.ts
@@ -11,6 +11,7 @@ import {
     FunctionExpression,
     getLocaleSpecificMessage,
     getTouchingPropertyName,
+    InternalNodeBuilderFlags,
     isArrowFunction,
     isBlock,
     isInJSFile,
@@ -126,7 +127,7 @@ function getInfo(context: RefactorContext): FunctionInfo | RefactorErrorInfo | u
         if (signature) {
             const typePredicate = typeChecker.getTypePredicateOfSignature(signature);
             if (typePredicate && typePredicate.type) {
-                const typePredicateTypeNode = typeChecker.typePredicateToTypePredicateNode(typePredicate, declaration, NodeBuilderFlags.NoTruncation);
+                const typePredicateTypeNode = typeChecker.typePredicateToTypePredicateNode(typePredicate, declaration, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames);
                 if (typePredicateTypeNode) {
                     return { declaration, returnTypeNode: typePredicateTypeNode };
                 }
@@ -141,7 +142,7 @@ function getInfo(context: RefactorContext): FunctionInfo | RefactorErrorInfo | u
         return { error: getLocaleSpecificMessage(Diagnostics.Could_not_determine_function_return_type) };
     }
 
-    const returnTypeNode = typeChecker.typeToTypeNode(returnType, declaration, NodeBuilderFlags.NoTruncation);
+    const returnTypeNode = typeChecker.typeToTypeNode(returnType, declaration, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames);
     if (returnTypeNode) {
         return { declaration, returnTypeNode };
     }
diff --git a/src/services/utilities.ts b/src/services/utilities.ts
index 55ab684196e3c..c3908e208b74f 100644
--- a/src/services/utilities.ts
+++ b/src/services/utilities.ts
@@ -132,6 +132,7 @@ import {
     ImportTypeNode,
     indexOfNode,
     IndexSignatureDeclaration,
+    InternalNodeBuilderFlags,
     InternalSymbolName,
     isAmbientModule,
     isAnyImportSyntax,
@@ -3440,7 +3441,7 @@ export function getTypeNodeIfAccessible(type: Type, enclosingScope: Node, progra
     const checker = program.getTypeChecker();
     let typeIsAccessible = true;
     const notAccessible = () => typeIsAccessible = false;
-    const res = checker.typeToTypeNode(type, enclosingScope, NodeBuilderFlags.NoTruncation, {
+    const res = checker.typeToTypeNode(type, enclosingScope, NodeBuilderFlags.NoTruncation, InternalNodeBuilderFlags.AllowUnresolvedNames, {
         trackSymbol: (symbol, declaration, meaning) => {
             typeIsAccessible = typeIsAccessible && checker.isSymbolAccessible(symbol, declaration, meaning, /*shouldComputeAliasToMarkVisible*/ false).accessibility === SymbolAccessibility.Accessible;
             return !typeIsAccessible;

From 278cb9489dbc8011c05573f26c33f46a005d3955 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Thu, 8 Aug 2024 13:38:46 -0700
Subject: [PATCH 07/11] Properly account for type parameters introduced by
 contextual types (#59516)

---
 src/compiler/checker.ts                       |  15 +-
 .../contextualOuterTypeParameters.symbols     |  90 ++++++++++
 .../contextualOuterTypeParameters.types       | 165 ++++++++++++++++++
 .../compiler/contextualOuterTypeParameters.ts |  28 +++
 4 files changed, 294 insertions(+), 4 deletions(-)
 create mode 100644 tests/baselines/reference/contextualOuterTypeParameters.symbols
 create mode 100644 tests/baselines/reference/contextualOuterTypeParameters.types
 create mode 100644 tests/cases/compiler/contextualOuterTypeParameters.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 3c6713a826280..9ca49d3cdee54 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -12573,7 +12573,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             if (!node) {
                 return undefined;
             }
-            switch (node.kind) {
+            const kind = node.kind;
+            switch (kind) {
                 case SyntaxKind.ClassDeclaration:
                 case SyntaxKind.ClassExpression:
                 case SyntaxKind.InterfaceDeclaration:
@@ -12595,15 +12596,21 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 case SyntaxKind.MappedType:
                 case SyntaxKind.ConditionalType: {
                     const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes);
-                    if (node.kind === SyntaxKind.MappedType) {
+                    if ((kind === SyntaxKind.FunctionExpression || kind === SyntaxKind.ArrowFunction || isObjectLiteralMethod(node)) && isContextSensitive(node as Expression | MethodDeclaration)) {
+                        const signature = firstOrUndefined(getSignaturesOfType(getTypeOfSymbol(getSymbolOfDeclaration(node as FunctionLikeDeclaration)), SignatureKind.Call));
+                        if (signature && signature.typeParameters) {
+                            return [...(outerTypeParameters || emptyArray), ...signature.typeParameters];
+                        }
+                    }
+                    if (kind === SyntaxKind.MappedType) {
                         return append(outerTypeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration((node as MappedTypeNode).typeParameter)));
                     }
-                    else if (node.kind === SyntaxKind.ConditionalType) {
+                    else if (kind === SyntaxKind.ConditionalType) {
                         return concatenate(outerTypeParameters, getInferTypeParameters(node as ConditionalTypeNode));
                     }
                     const outerAndOwnTypeParameters = appendTypeParameters(outerTypeParameters, getEffectiveTypeParameterDeclarations(node as DeclarationWithTypeParameters));
                     const thisType = includeThisTypes &&
-                        (node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression || node.kind === SyntaxKind.InterfaceDeclaration || isJSConstructor(node)) &&
+                        (kind === SyntaxKind.ClassDeclaration || kind === SyntaxKind.ClassExpression || kind === SyntaxKind.InterfaceDeclaration || isJSConstructor(node)) &&
                         getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node as ClassLikeDeclaration | InterfaceDeclaration)).thisType;
                     return thisType ? append(outerAndOwnTypeParameters, thisType) : outerAndOwnTypeParameters;
                 }
diff --git a/tests/baselines/reference/contextualOuterTypeParameters.symbols b/tests/baselines/reference/contextualOuterTypeParameters.symbols
new file mode 100644
index 0000000000000..72ec61e99b1a7
--- /dev/null
+++ b/tests/baselines/reference/contextualOuterTypeParameters.symbols
@@ -0,0 +1,90 @@
+//// [tests/cases/compiler/contextualOuterTypeParameters.ts] ////
+
+=== contextualOuterTypeParameters.ts ===
+// https://github.com/microsoft/TypeScript/issues/59450
+
+declare function f(fun: <T>(t: T) => void): void
+>f : Symbol(f, Decl(contextualOuterTypeParameters.ts, 0, 0))
+>fun : Symbol(fun, Decl(contextualOuterTypeParameters.ts, 2, 19))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 2, 25))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 2, 28))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 2, 25))
+
+f(t => {
+>f : Symbol(f, Decl(contextualOuterTypeParameters.ts, 0, 0))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 4, 2))
+
+    type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : Symbol(isArray, Decl(contextualOuterTypeParameters.ts, 4, 8))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 4, 2))
+
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : Symbol(IsObject, Decl(contextualOuterTypeParameters.ts, 5, 64))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 6, 21))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 4, 2))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 6, 45))
+
+});
+
+const fn1: <T>(x: T) => void = t => {
+>fn1 : Symbol(fn1, Decl(contextualOuterTypeParameters.ts, 9, 5))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 9, 12))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 9, 15))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 9, 12))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 9, 30))
+
+    type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : Symbol(isArray, Decl(contextualOuterTypeParameters.ts, 9, 37))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 9, 30))
+
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : Symbol(IsObject, Decl(contextualOuterTypeParameters.ts, 10, 64))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 11, 21))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 9, 30))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 11, 45))
+
+};
+
+const fn2: <T>(x: T) => void = function test(t) {
+>fn2 : Symbol(fn2, Decl(contextualOuterTypeParameters.ts, 14, 5))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 14, 12))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 14, 15))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 14, 12))
+>test : Symbol(test, Decl(contextualOuterTypeParameters.ts, 14, 30))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 14, 45))
+
+    type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : Symbol(isArray, Decl(contextualOuterTypeParameters.ts, 14, 49))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 14, 45))
+
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : Symbol(IsObject, Decl(contextualOuterTypeParameters.ts, 15, 64))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 16, 21))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 14, 45))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 16, 45))
+
+};
+
+const obj: { f: <T>(x: T) => void } = {
+>obj : Symbol(obj, Decl(contextualOuterTypeParameters.ts, 19, 5))
+>f : Symbol(f, Decl(contextualOuterTypeParameters.ts, 19, 12))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 19, 17))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 19, 20))
+>T : Symbol(T, Decl(contextualOuterTypeParameters.ts, 19, 17))
+
+    f(t) {
+>f : Symbol(f, Decl(contextualOuterTypeParameters.ts, 19, 39))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 20, 6))
+
+        type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : Symbol(isArray, Decl(contextualOuterTypeParameters.ts, 20, 10))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 20, 6))
+
+        type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : Symbol(IsObject, Decl(contextualOuterTypeParameters.ts, 21, 68))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 22, 25))
+>t : Symbol(t, Decl(contextualOuterTypeParameters.ts, 20, 6))
+>x : Symbol(x, Decl(contextualOuterTypeParameters.ts, 22, 49))
+    }
+};
+
diff --git a/tests/baselines/reference/contextualOuterTypeParameters.types b/tests/baselines/reference/contextualOuterTypeParameters.types
new file mode 100644
index 0000000000000..d18525d58c195
--- /dev/null
+++ b/tests/baselines/reference/contextualOuterTypeParameters.types
@@ -0,0 +1,165 @@
+//// [tests/cases/compiler/contextualOuterTypeParameters.ts] ////
+
+=== contextualOuterTypeParameters.ts ===
+// https://github.com/microsoft/TypeScript/issues/59450
+
+declare function f(fun: <T>(t: T) => void): void
+>f : (fun: <T>(t: T) => void) => void
+>  : ^   ^^                 ^^^^^    
+>fun : <T>(t: T) => void
+>    : ^ ^^ ^^ ^^^^^    
+>t : T
+>  : ^
+
+f(t => {
+>f(t => {    type isArray = (typeof t)[] extends string[] ? true : false;    type IsObject = { x: typeof t } extends { x: string } ? true : false;}) : void
+>                                                                                                                                                    : ^^^^
+>f : (fun: <T>(t: T) => void) => void
+>  : ^   ^^                 ^^^^^    
+>t => {    type isArray = (typeof t)[] extends string[] ? true : false;    type IsObject = { x: typeof t } extends { x: string } ? true : false;} : <T>(t: T) => void
+>                                                                                                                                                 : ^ ^^ ^^^^^^^^^^^^
+>t : T
+>  : ^
+
+    type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : T[] extends string[] ? true : false
+>        : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>t : T
+>  : ^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : { x: typeof t; } extends { x: string; } ? true : false
+>         : ^^^^^        ^^^^^^^^^^^^^^^^^      ^^^^^^^^^^^^^^^^^^
+>x : T
+>  : ^
+>t : T
+>  : ^
+>x : string
+>  : ^^^^^^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+
+});
+
+const fn1: <T>(x: T) => void = t => {
+>fn1 : <T>(x: T) => void
+>    : ^ ^^ ^^ ^^^^^    
+>x : T
+>  : ^
+>t => {    type isArray = (typeof t)[] extends string[] ? true : false;    type IsObject = { x: typeof t } extends { x: string } ? true : false;} : <T>(t: T) => void
+>                                                                                                                                                 : ^ ^^ ^^^^^^^^^^^^
+>t : T
+>  : ^
+
+    type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : T[] extends string[] ? true : false
+>        : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>t : T
+>  : ^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : { x: typeof t; } extends { x: string; } ? true : false
+>         : ^^^^^        ^^^^^^^^^^^^^^^^^      ^^^^^^^^^^^^^^^^^^
+>x : T
+>  : ^
+>t : T
+>  : ^
+>x : string
+>  : ^^^^^^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+
+};
+
+const fn2: <T>(x: T) => void = function test(t) {
+>fn2 : <T>(x: T) => void
+>    : ^ ^^ ^^ ^^^^^    
+>x : T
+>  : ^
+>function test(t) {    type isArray = (typeof t)[] extends string[] ? true : false;    type IsObject = { x: typeof t } extends { x: string } ? true : false;} : <T>(t: T) => void
+>                                                                                                                                                             : ^ ^^ ^^^^^^^^^^^^
+>test : <T>(t: T) => void
+>     : ^ ^^ ^^^^^^^^^^^^
+>t : T
+>  : ^
+
+    type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : T[] extends string[] ? true : false
+>        : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>t : T
+>  : ^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : { x: typeof t; } extends { x: string; } ? true : false
+>         : ^^^^^        ^^^^^^^^^^^^^^^^^      ^^^^^^^^^^^^^^^^^^
+>x : T
+>  : ^
+>t : T
+>  : ^
+>x : string
+>  : ^^^^^^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+
+};
+
+const obj: { f: <T>(x: T) => void } = {
+>obj : { f: <T>(x: T) => void; }
+>    : ^^^^^                 ^^^
+>f : <T>(x: T) => void
+>  : ^ ^^ ^^ ^^^^^    
+>x : T
+>  : ^
+>{    f(t) {        type isArray = (typeof t)[] extends string[] ? true : false;        type IsObject = { x: typeof t } extends { x: string } ? true : false;    }} : { f<T>(t: T): void; }
+>                                                                                                                                                                   : ^^^^ ^^ ^^^^^^^^^^^^^
+
+    f(t) {
+>f : <T>(t: T) => void
+>  : ^ ^^ ^^^^^^^^^^^^
+>t : T
+>  : ^
+
+        type isArray = (typeof t)[] extends string[] ? true : false;
+>isArray : T[] extends string[] ? true : false
+>        : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>t : T
+>  : ^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+
+        type IsObject = { x: typeof t } extends { x: string } ? true : false;
+>IsObject : { x: typeof t; } extends { x: string; } ? true : false
+>         : ^^^^^        ^^^^^^^^^^^^^^^^^      ^^^^^^^^^^^^^^^^^^
+>x : T
+>  : ^
+>t : T
+>  : ^
+>x : string
+>  : ^^^^^^
+>true : true
+>     : ^^^^
+>false : false
+>      : ^^^^^
+    }
+};
+
diff --git a/tests/cases/compiler/contextualOuterTypeParameters.ts b/tests/cases/compiler/contextualOuterTypeParameters.ts
new file mode 100644
index 0000000000000..3ed24f2a3c7d7
--- /dev/null
+++ b/tests/cases/compiler/contextualOuterTypeParameters.ts
@@ -0,0 +1,28 @@
+// @strict: true
+// @noemit: true
+
+// https://github.com/microsoft/TypeScript/issues/59450
+
+declare function f(fun: <T>(t: T) => void): void
+
+f(t => {
+    type isArray = (typeof t)[] extends string[] ? true : false;
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+});
+
+const fn1: <T>(x: T) => void = t => {
+    type isArray = (typeof t)[] extends string[] ? true : false;
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+};
+
+const fn2: <T>(x: T) => void = function test(t) {
+    type isArray = (typeof t)[] extends string[] ? true : false;
+    type IsObject = { x: typeof t } extends { x: string } ? true : false;
+};
+
+const obj: { f: <T>(x: T) => void } = {
+    f(t) {
+        type isArray = (typeof t)[] extends string[] ? true : false;
+        type IsObject = { x: typeof t } extends { x: string } ? true : false;
+    }
+};

From 1bb1d2a6105a9a05a10409265f35cbe37d89b3e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Fri, 9 Aug 2024 05:24:10 +0200
Subject: [PATCH 08/11] Fixed regression in generic signature instantiation
 with default type args (#59510)

---
 src/compiler/checker.ts                       |  8 +-
 ...nericCallInferenceConditionalType2.symbols | 85 ++++++++++++++++
 ...genericCallInferenceConditionalType2.types | 98 +++++++++++++++++++
 .../genericCallInferenceConditionalType2.ts   | 29 ++++++
 4 files changed, 218 insertions(+), 2 deletions(-)
 create mode 100644 tests/baselines/reference/genericCallInferenceConditionalType2.symbols
 create mode 100644 tests/baselines/reference/genericCallInferenceConditionalType2.types
 create mode 100644 tests/cases/compiler/genericCallInferenceConditionalType2.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 9ca49d3cdee54..4b8d44e62fc9f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -16040,8 +16040,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         return instantiateSignature(signature, createSignatureTypeMapper(signature, typeArguments), /*eraseTypeParameters*/ true);
     }
 
+    function getTypeParametersForMapper(signature: Signature) {
+        return sameMap(signature.typeParameters, tp => tp.mapper ? instantiateType(tp, tp.mapper) : tp);
+    }
+
     function createSignatureTypeMapper(signature: Signature, typeArguments: readonly Type[] | undefined): TypeMapper {
-        return createTypeMapper(sameMap(signature.typeParameters!, tp => tp.mapper ? instantiateType(tp, tp.mapper) : tp), typeArguments);
+        return createTypeMapper(getTypeParametersForMapper(signature)!, typeArguments);
     }
 
     function getErasedSignature(signature: Signature): Signature {
@@ -34930,7 +34934,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     // Instantiate a generic signature in the context of a non-generic signature (section 3.8.5 in TypeScript spec)
     function instantiateSignatureInContextOf(signature: Signature, contextualSignature: Signature, inferenceContext?: InferenceContext, compareTypes?: TypeComparer): Signature {
-        const context = createInferenceContext(signature.typeParameters!, signature, InferenceFlags.None, compareTypes);
+        const context = createInferenceContext(getTypeParametersForMapper(signature)!, signature, InferenceFlags.None, compareTypes);
         // We clone the inferenceContext to avoid fixing. For example, when the source signature is <T>(x: T) => T[] and
         // the contextual signature is (...args: A) => B, we want to infer the element type of A's constraint (say 'any')
         // for T but leave it possible to later infer '[any]' back to A.
diff --git a/tests/baselines/reference/genericCallInferenceConditionalType2.symbols b/tests/baselines/reference/genericCallInferenceConditionalType2.symbols
new file mode 100644
index 0000000000000..1f88ec594ad2b
--- /dev/null
+++ b/tests/baselines/reference/genericCallInferenceConditionalType2.symbols
@@ -0,0 +1,85 @@
+//// [tests/cases/compiler/genericCallInferenceConditionalType2.ts] ////
+
+=== genericCallInferenceConditionalType2.ts ===
+// https://github.com/microsoft/TypeScript/issues/59490
+
+type ComponentProps<T> = T extends (props: infer P) => unknown ? P : never;
+>ComponentProps : Symbol(ComponentProps, Decl(genericCallInferenceConditionalType2.ts, 0, 0))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 2, 20))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 2, 20))
+>props : Symbol(props, Decl(genericCallInferenceConditionalType2.ts, 2, 36))
+>P : Symbol(P, Decl(genericCallInferenceConditionalType2.ts, 2, 48))
+>P : Symbol(P, Decl(genericCallInferenceConditionalType2.ts, 2, 48))
+
+declare function wrapComponent<P>(
+>wrapComponent : Symbol(wrapComponent, Decl(genericCallInferenceConditionalType2.ts, 2, 75))
+>P : Symbol(P, Decl(genericCallInferenceConditionalType2.ts, 4, 31))
+
+  component: (props: P) => unknown,
+>component : Symbol(component, Decl(genericCallInferenceConditionalType2.ts, 4, 34))
+>props : Symbol(props, Decl(genericCallInferenceConditionalType2.ts, 5, 14))
+>P : Symbol(P, Decl(genericCallInferenceConditionalType2.ts, 4, 31))
+
+): (props: P) => unknown;
+>props : Symbol(props, Decl(genericCallInferenceConditionalType2.ts, 6, 4))
+>P : Symbol(P, Decl(genericCallInferenceConditionalType2.ts, 4, 31))
+
+const WrappedComponent = wrapComponent(
+>WrappedComponent : Symbol(WrappedComponent, Decl(genericCallInferenceConditionalType2.ts, 8, 5))
+>wrapComponent : Symbol(wrapComponent, Decl(genericCallInferenceConditionalType2.ts, 2, 75))
+
+  <T extends string = "span">(props: {
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 9, 3))
+>props : Symbol(props, Decl(genericCallInferenceConditionalType2.ts, 9, 30))
+
+    as?: T | undefined;
+>as : Symbol(as, Decl(genericCallInferenceConditionalType2.ts, 9, 38))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 9, 3))
+
+    className?: string;
+>className : Symbol(className, Decl(genericCallInferenceConditionalType2.ts, 10, 23))
+
+  }) => {
+    return null;
+  },
+);
+
+type RetrievedProps = ComponentProps<typeof WrappedComponent>;
+>RetrievedProps : Symbol(RetrievedProps, Decl(genericCallInferenceConditionalType2.ts, 15, 2))
+>ComponentProps : Symbol(ComponentProps, Decl(genericCallInferenceConditionalType2.ts, 0, 0))
+>WrappedComponent : Symbol(WrappedComponent, Decl(genericCallInferenceConditionalType2.ts, 8, 5))
+
+declare const f: <T>(f: (x: T) => unknown) => (x: T) => unknown
+>f : Symbol(f, Decl(genericCallInferenceConditionalType2.ts, 19, 13))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 19, 18))
+>f : Symbol(f, Decl(genericCallInferenceConditionalType2.ts, 19, 21))
+>x : Symbol(x, Decl(genericCallInferenceConditionalType2.ts, 19, 25))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 19, 18))
+>x : Symbol(x, Decl(genericCallInferenceConditionalType2.ts, 19, 47))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 19, 18))
+
+declare const g: <T extends unknown = string>(x: { foo: T }) => unknown
+>g : Symbol(g, Decl(genericCallInferenceConditionalType2.ts, 20, 13))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 20, 18))
+>x : Symbol(x, Decl(genericCallInferenceConditionalType2.ts, 20, 46))
+>foo : Symbol(foo, Decl(genericCallInferenceConditionalType2.ts, 20, 50))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 20, 18))
+
+const h = f(g)
+>h : Symbol(h, Decl(genericCallInferenceConditionalType2.ts, 22, 5))
+>f : Symbol(f, Decl(genericCallInferenceConditionalType2.ts, 19, 13))
+>g : Symbol(g, Decl(genericCallInferenceConditionalType2.ts, 20, 13))
+
+type FirstParameter<T> = T extends (x: infer P) => unknown ? P : unknown
+>FirstParameter : Symbol(FirstParameter, Decl(genericCallInferenceConditionalType2.ts, 22, 14))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 24, 20))
+>T : Symbol(T, Decl(genericCallInferenceConditionalType2.ts, 24, 20))
+>x : Symbol(x, Decl(genericCallInferenceConditionalType2.ts, 24, 36))
+>P : Symbol(P, Decl(genericCallInferenceConditionalType2.ts, 24, 44))
+>P : Symbol(P, Decl(genericCallInferenceConditionalType2.ts, 24, 44))
+
+type X = FirstParameter<typeof h>['foo']
+>X : Symbol(X, Decl(genericCallInferenceConditionalType2.ts, 24, 72))
+>FirstParameter : Symbol(FirstParameter, Decl(genericCallInferenceConditionalType2.ts, 22, 14))
+>h : Symbol(h, Decl(genericCallInferenceConditionalType2.ts, 22, 5))
+
diff --git a/tests/baselines/reference/genericCallInferenceConditionalType2.types b/tests/baselines/reference/genericCallInferenceConditionalType2.types
new file mode 100644
index 0000000000000..c9c143a7dd8d2
--- /dev/null
+++ b/tests/baselines/reference/genericCallInferenceConditionalType2.types
@@ -0,0 +1,98 @@
+//// [tests/cases/compiler/genericCallInferenceConditionalType2.ts] ////
+
+=== genericCallInferenceConditionalType2.ts ===
+// https://github.com/microsoft/TypeScript/issues/59490
+
+type ComponentProps<T> = T extends (props: infer P) => unknown ? P : never;
+>ComponentProps : ComponentProps<T>
+>               : ^^^^^^^^^^^^^^^^^
+>props : P
+>      : ^
+
+declare function wrapComponent<P>(
+>wrapComponent : <P>(component: (props: P) => unknown) => (props: P) => unknown
+>              : ^ ^^         ^^                     ^^^^^                     
+
+  component: (props: P) => unknown,
+>component : (props: P) => unknown
+>          : ^     ^^ ^^^^^       
+>props : P
+>      : ^
+
+): (props: P) => unknown;
+>props : P
+>      : ^
+
+const WrappedComponent = wrapComponent(
+>WrappedComponent : <T extends string = "span">(props: { as?: T | undefined; className?: string; }) => unknown
+>                 : ^ ^^^^^^^^^      ^^^^^^^^^^^     ^^^^^^^^^             ^^^^^^^^^^^^^^      ^^^^^^^^       
+>wrapComponent(  <T extends string = "span">(props: {    as?: T | undefined;    className?: string;  }) => {    return null;  },) : <T extends string = "span">(props: { as?: T | undefined; className?: string; }) => unknown
+>                                                                                                                                 : ^ ^^^^^^^^^      ^^^^^^^^^^^     ^^^^^^^^^             ^^^^^^^^^^^^^^      ^^^^^^^^       
+>wrapComponent : <P>(component: (props: P) => unknown) => (props: P) => unknown
+>              : ^ ^^         ^^                     ^^^^^                     
+
+  <T extends string = "span">(props: {
+><T extends string = "span">(props: {    as?: T | undefined;    className?: string;  }) => {    return null;  } : <T extends string = "span">(props: { as?: T | undefined; className?: string; }) => null
+>                                                                                                               : ^ ^^^^^^^^^      ^^^^^^^^^^^     ^^                                           ^^^^^^^^^
+>props : { as?: T | undefined; className?: string; }
+>      : ^^^^^^^             ^^^^^^^^^^^^^^      ^^^
+
+    as?: T | undefined;
+>as : T | undefined
+>   : ^^^^^^^^^^^^^
+
+    className?: string;
+>className : string | undefined
+>          : ^^^^^^^^^^^^^^^^^^
+
+  }) => {
+    return null;
+  },
+);
+
+type RetrievedProps = ComponentProps<typeof WrappedComponent>;
+>RetrievedProps : { as?: string | undefined; className?: string; }
+>               : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^      ^^^
+>WrappedComponent : <T extends string = "span">(props: { as?: T | undefined; className?: string; }) => unknown
+>                 : ^ ^^^^^^^^^      ^^^^^^^^^^^     ^^^^^^^^^             ^^^^^^^^^^^^^^      ^^^^^^^^       
+
+declare const f: <T>(f: (x: T) => unknown) => (x: T) => unknown
+>f : <T>(f: (x: T) => unknown) => (x: T) => unknown
+>  : ^ ^^ ^^                 ^^^^^                 
+>f : (x: T) => unknown
+>  : ^ ^^ ^^^^^       
+>x : T
+>  : ^
+>x : T
+>  : ^
+
+declare const g: <T extends unknown = string>(x: { foo: T }) => unknown
+>g : <T extends unknown = string>(x: { foo: T; }) => unknown
+>  : ^ ^^^^^^^^^       ^^^^^^^^^^^ ^^           ^^^^^       
+>x : { foo: T; }
+>  : ^^^^^^^ ^^^
+>foo : T
+>    : ^
+
+const h = f(g)
+>h : <T extends unknown = string>(x: { foo: T; }) => unknown
+>  : ^ ^^^^^^^^^       ^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^       
+>f(g) : <T extends unknown = string>(x: { foo: T; }) => unknown
+>     : ^ ^^^^^^^^^       ^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^       
+>f : <T>(f: (x: T) => unknown) => (x: T) => unknown
+>  : ^ ^^ ^^                 ^^^^^                 
+>g : <T extends unknown = string>(x: { foo: T; }) => unknown
+>  : ^ ^^^^^^^^^       ^^^^^^^^^^^ ^^           ^^^^^       
+
+type FirstParameter<T> = T extends (x: infer P) => unknown ? P : unknown
+>FirstParameter : FirstParameter<T>
+>               : ^^^^^^^^^^^^^^^^^
+>x : P
+>  : ^
+
+type X = FirstParameter<typeof h>['foo']
+>X : unknown
+>  : ^^^^^^^
+>h : <T extends unknown = string>(x: { foo: T; }) => unknown
+>  : ^ ^^^^^^^^^       ^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^       
+
diff --git a/tests/cases/compiler/genericCallInferenceConditionalType2.ts b/tests/cases/compiler/genericCallInferenceConditionalType2.ts
new file mode 100644
index 0000000000000..38afcf985efa6
--- /dev/null
+++ b/tests/cases/compiler/genericCallInferenceConditionalType2.ts
@@ -0,0 +1,29 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/59490
+
+type ComponentProps<T> = T extends (props: infer P) => unknown ? P : never;
+
+declare function wrapComponent<P>(
+  component: (props: P) => unknown,
+): (props: P) => unknown;
+
+const WrappedComponent = wrapComponent(
+  <T extends string = "span">(props: {
+    as?: T | undefined;
+    className?: string;
+  }) => {
+    return null;
+  },
+);
+
+type RetrievedProps = ComponentProps<typeof WrappedComponent>;
+
+declare const f: <T>(f: (x: T) => unknown) => (x: T) => unknown
+declare const g: <T extends unknown = string>(x: { foo: T }) => unknown
+
+const h = f(g)
+
+type FirstParameter<T> = T extends (x: infer P) => unknown ? P : unknown
+type X = FirstParameter<typeof h>['foo']

From 09caaf60aa4101813bedc41f21ad84318aadd29a Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrewbranch@users.noreply.github.com>
Date: Fri, 9 Aug 2024 11:12:18 -0700
Subject: [PATCH 09/11] Add `autoImportSpecifierExcludeRegexes` preference
 (#59543)

---
 src/compiler/moduleSpecifiers.ts              | 72 ++++++++++++++++---
 src/compiler/types.ts                         |  1 +
 src/services/completions.ts                   | 11 +--
 tests/baselines/reference/api/typescript.d.ts |  1 +
 .../autoImportSpecifierExcludeRegexes1.ts     | 61 ++++++++++++++++
 .../autoImportSpecifierExcludeRegexes2.ts     | 25 +++++++
 .../autoImportSpecifierExcludeRegexes3.ts     | 25 +++++++
 tests/cases/fourslash/fourslash.ts            |  1 +
 8 files changed, 183 insertions(+), 14 deletions(-)
 create mode 100644 tests/cases/fourslash/autoImportSpecifierExcludeRegexes1.ts
 create mode 100644 tests/cases/fourslash/autoImportSpecifierExcludeRegexes2.ts
 create mode 100644 tests/cases/fourslash/autoImportSpecifierExcludeRegexes3.ts

diff --git a/src/compiler/moduleSpecifiers.ts b/src/compiler/moduleSpecifiers.ts
index f380ff56a02f6..f193aeb6784f1 100644
--- a/src/compiler/moduleSpecifiers.ts
+++ b/src/compiler/moduleSpecifiers.ts
@@ -83,6 +83,7 @@ import {
     mapDefined,
     MapLike,
     matchPatternOrExact,
+    memoizeOne,
     min,
     ModuleDeclaration,
     ModuleKind,
@@ -127,6 +128,34 @@ import {
     UserPreferences,
 } from "./_namespaces/ts.js";
 
+const stringToRegex = memoizeOne((pattern: string) => {
+    try {
+        let slash = pattern.indexOf("/");
+        if (slash !== 0) {
+            // No leading slash, treat as a pattern
+            return new RegExp(pattern);
+        }
+        const lastSlash = pattern.lastIndexOf("/");
+        if (slash === lastSlash) {
+            // Only one slash, treat as a pattern
+            return new RegExp(pattern);
+        }
+        while ((slash = pattern.indexOf("/", slash + 1)) !== lastSlash) {
+            if (pattern[slash - 1] !== "\\") {
+                // Unescaped middle slash, treat as a pattern
+                return new RegExp(pattern);
+            }
+        }
+        // Only case-insensitive and unicode flags make sense
+        const flags = pattern.substring(lastSlash + 1).replace(/[^iu]/g, "");
+        pattern = pattern.substring(1, lastSlash);
+        return new RegExp(pattern, flags);
+    }
+    catch {
+        return undefined;
+    }
+});
+
 // Used by importFixes, getEditsForFileRename, and declaration emit to synthesize import module specifiers.
 
 /** @internal */
@@ -144,11 +173,12 @@ export interface ModuleSpecifierPreferences {
      * @param syntaxImpliedNodeFormat Used when the import syntax implies ESM or CJS irrespective of the mode of the file.
      */
     getAllowedEndingsInPreferredOrder(syntaxImpliedNodeFormat?: ResolutionMode): ModuleSpecifierEnding[];
+    readonly excludeRegexes?: readonly string[];
 }
 
 /** @internal */
 export function getModuleSpecifierPreferences(
-    { importModuleSpecifierPreference, importModuleSpecifierEnding }: UserPreferences,
+    { importModuleSpecifierPreference, importModuleSpecifierEnding, autoImportSpecifierExcludeRegexes }: UserPreferences,
     host: Pick<ModuleSpecifierResolutionHost, "getDefaultResolutionModeForFile">,
     compilerOptions: CompilerOptions,
     importingSourceFile: Pick<SourceFile, "fileName" | "impliedNodeFormat">,
@@ -156,6 +186,7 @@ export function getModuleSpecifierPreferences(
 ): ModuleSpecifierPreferences {
     const filePreferredEnding = getPreferredEnding();
     return {
+        excludeRegexes: autoImportSpecifierExcludeRegexes,
         relativePreference: oldImportSpecifier !== undefined ? (isExternalModuleNameRelative(oldImportSpecifier) ?
             RelativePreference.Relative :
             RelativePreference.NonRelative) :
@@ -362,7 +393,13 @@ export function getModuleSpecifiersWithCacheInfo(
 ): ModuleSpecifierResult {
     let computedWithoutCache = false;
     const ambient = tryGetModuleNameFromAmbientModule(moduleSymbol, checker);
-    if (ambient) return { kind: "ambient", moduleSpecifiers: [ambient], computedWithoutCache };
+    if (ambient) {
+        return {
+            kind: "ambient",
+            moduleSpecifiers: !(forAutoImport && isExcludedByRegex(ambient, userPreferences.autoImportSpecifierExcludeRegexes)) ? [ambient] : emptyArray,
+            computedWithoutCache,
+        };
+    }
 
     // eslint-disable-next-line prefer-const
     let [kind, specifiers, moduleSourceFile, modulePaths, cache] = tryGetModuleSpecifiersFromCacheWorker(
@@ -459,11 +496,13 @@ function computeModuleSpecifiers(
         const specifier = modulePath.isInNodeModules
             ? tryGetModuleNameAsNodeModule(modulePath, info, importingSourceFile, host, compilerOptions, userPreferences, /*packageNameOnly*/ undefined, options.overrideImportMode)
             : undefined;
-        nodeModulesSpecifiers = append(nodeModulesSpecifiers, specifier);
-        if (specifier && modulePath.isRedirect) {
-            // If we got a specifier for a redirect, it was a bare package specifier (e.g. "@foo/bar",
-            // not "@foo/bar/path/to/file"). No other specifier will be this good, so stop looking.
-            return { kind: "node_modules", moduleSpecifiers: nodeModulesSpecifiers!, computedWithoutCache: true };
+        if (specifier && !(forAutoImport && isExcludedByRegex(specifier, preferences.excludeRegexes))) {
+            nodeModulesSpecifiers = append(nodeModulesSpecifiers, specifier);
+            if (modulePath.isRedirect) {
+                // If we got a specifier for a redirect, it was a bare package specifier (e.g. "@foo/bar",
+                // not "@foo/bar/path/to/file"). No other specifier will be this good, so stop looking.
+                return { kind: "node_modules", moduleSpecifiers: nodeModulesSpecifiers, computedWithoutCache: true };
+            }
         }
 
         if (!specifier) {
@@ -476,7 +515,7 @@ function computeModuleSpecifiers(
                 preferences,
                 /*pathsOnly*/ modulePath.isRedirect,
             );
-            if (!local) {
+            if (!local || forAutoImport && isExcludedByRegex(local, preferences.excludeRegexes)) {
                 continue;
             }
             if (modulePath.isRedirect) {
@@ -512,7 +551,11 @@ function computeModuleSpecifiers(
     return pathsSpecifiers?.length ? { kind: "paths", moduleSpecifiers: pathsSpecifiers, computedWithoutCache: true } :
         redirectPathsSpecifiers?.length ? { kind: "redirect", moduleSpecifiers: redirectPathsSpecifiers, computedWithoutCache: true } :
         nodeModulesSpecifiers?.length ? { kind: "node_modules", moduleSpecifiers: nodeModulesSpecifiers, computedWithoutCache: true } :
-        { kind: "relative", moduleSpecifiers: Debug.checkDefined(relativeSpecifiers), computedWithoutCache: true };
+        { kind: "relative", moduleSpecifiers: relativeSpecifiers ?? emptyArray, computedWithoutCache: true };
+}
+
+function isExcludedByRegex(moduleSpecifier: string, excludeRegexes: readonly string[] | undefined): boolean {
+    return some(excludeRegexes, pattern => !!stringToRegex(pattern)?.test(moduleSpecifier));
 }
 
 interface Info {
@@ -536,7 +579,7 @@ function getInfo(importingSourceFileName: string, host: ModuleSpecifierResolutio
 
 function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, preferences: ModuleSpecifierPreferences): string;
 function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, preferences: ModuleSpecifierPreferences, pathsOnly?: boolean): string | undefined;
-function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, { getAllowedEndingsInPreferredOrder: getAllowedEndingsInPrefererredOrder, relativePreference }: ModuleSpecifierPreferences, pathsOnly?: boolean): string | undefined {
+function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, { getAllowedEndingsInPreferredOrder: getAllowedEndingsInPrefererredOrder, relativePreference, excludeRegexes }: ModuleSpecifierPreferences, pathsOnly?: boolean): string | undefined {
     const { baseUrl, paths, rootDirs } = compilerOptions;
     if (pathsOnly && !paths) {
         return undefined;
@@ -568,6 +611,15 @@ function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOpt
         return relativePath;
     }
 
+    const relativeIsExcluded = isExcludedByRegex(relativePath, excludeRegexes);
+    const nonRelativeIsExcluded = isExcludedByRegex(maybeNonRelative, excludeRegexes);
+    if (!relativeIsExcluded && nonRelativeIsExcluded) {
+        return relativePath;
+    }
+    if (relativeIsExcluded && !nonRelativeIsExcluded) {
+        return maybeNonRelative;
+    }
+
     if (relativePreference === RelativePreference.NonRelative && !pathIsRelative(maybeNonRelative)) {
         return maybeNonRelative;
     }
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 3f5306cec0383..fb3022c5500c9 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -10260,6 +10260,7 @@ export interface UserPreferences {
     readonly interactiveInlayHints?: boolean;
     readonly allowRenameOfImportPath?: boolean;
     readonly autoImportFileExcludePatterns?: string[];
+    readonly autoImportSpecifierExcludeRegexes?: string[];
     readonly preferTypeOnlyAutoImports?: boolean;
     /**
      * Indicates whether imports should be organized in a case-insensitive manner.
diff --git a/src/services/completions.ts b/src/services/completions.ts
index ee67c03331563..ac88e4bf668a5 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -84,7 +84,6 @@ import {
     getEffectiveBaseTypeNode,
     getEffectiveModifierFlags,
     getEffectiveTypeAnnotationNode,
-    getEmitModuleResolutionKind,
     getEmitScriptTarget,
     getEscapedTextOfIdentifierOrLiteral,
     getEscapedTextOfJsxAttributeName,
@@ -106,6 +105,7 @@ import {
     getPropertyNameForPropertyNameNode,
     getQuotePreference,
     getReplacementSpanForContextToken,
+    getResolvePackageJsonExports,
     getRootDeclaration,
     getSourceFileOfModule,
     getSwitchedType,
@@ -301,7 +301,6 @@ import {
     ModuleDeclaration,
     moduleExportNameTextEscaped,
     ModuleReference,
-    moduleResolutionSupportsPackageJsonExportsAndImports,
     NamedImportBindings,
     newCaseClauseTracker,
     Node,
@@ -629,12 +628,16 @@ function resolvingModuleSpecifiers<TReturn>(
     cb: (context: ModuleSpecifierResolutionContext) => TReturn,
 ): TReturn {
     const start = timestamp();
-    // Under `--moduleResolution nodenext`, we have to resolve module specifiers up front, because
+    // Under `--moduleResolution nodenext` or `bundler`, we have to resolve module specifiers up front, because
     // package.json exports can mean we *can't* resolve a module specifier (that doesn't include a
     // relative path into node_modules), and we want to filter those completions out entirely.
     // Import statement completions always need specifier resolution because the module specifier is
     // part of their `insertText`, not the `codeActions` creating edits away from the cursor.
-    const needsFullResolution = isForImportStatementCompletion || moduleResolutionSupportsPackageJsonExportsAndImports(getEmitModuleResolutionKind(program.getCompilerOptions()));
+    // Finally, `autoImportSpecifierExcludeRegexes` necessitates eagerly resolving module specifiers
+    // because completion items are being explcitly filtered out by module specifier.
+    const needsFullResolution = isForImportStatementCompletion
+        || getResolvePackageJsonExports(program.getCompilerOptions())
+        || preferences.autoImportSpecifierExcludeRegexes?.length;
     let skippedAny = false;
     let ambientCount = 0;
     let resolvedCount = 0;
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 0e82d5ba67891..0a0d0a2f8dd95 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -8241,6 +8241,7 @@ declare namespace ts {
         readonly interactiveInlayHints?: boolean;
         readonly allowRenameOfImportPath?: boolean;
         readonly autoImportFileExcludePatterns?: string[];
+        readonly autoImportSpecifierExcludeRegexes?: string[];
         readonly preferTypeOnlyAutoImports?: boolean;
         /**
          * Indicates whether imports should be organized in a case-insensitive manner.
diff --git a/tests/cases/fourslash/autoImportSpecifierExcludeRegexes1.ts b/tests/cases/fourslash/autoImportSpecifierExcludeRegexes1.ts
new file mode 100644
index 0000000000000..f3eff409abf54
--- /dev/null
+++ b/tests/cases/fourslash/autoImportSpecifierExcludeRegexes1.ts
@@ -0,0 +1,61 @@
+/// <reference path="fourslash.ts" />
+
+// @module: preserve
+
+// @Filename: /node_modules/lib/index.d.ts
+//// declare module "ambient" {
+////     export const x: number;
+//// }
+//// declare module "ambient/utils" {
+////    export const x: number;
+//// }
+
+// @Filename: /index.ts
+//// x/**/
+
+verify.importFixModuleSpecifiers("", ["ambient", "ambient/utils"]);
+verify.importFixModuleSpecifiers("", ["ambient"], { autoImportSpecifierExcludeRegexes: ["utils"] });
+// case sensitive, no match
+verify.importFixModuleSpecifiers("", ["ambient", "ambient/utils"], { autoImportSpecifierExcludeRegexes: ["/UTILS/"] });
+// case insensitive flag given
+verify.importFixModuleSpecifiers("", ["ambient"], { autoImportSpecifierExcludeRegexes: ["/UTILS/i"] });
+// invalid due to unescaped slash, treated as pattern
+verify.importFixModuleSpecifiers("", ["ambient", "ambient/utils"], { autoImportSpecifierExcludeRegexes: ["/ambient/utils/"] });
+verify.importFixModuleSpecifiers("", ["ambient"], { autoImportSpecifierExcludeRegexes: ["/ambient\\/utils/"] });
+// no trailing slash, treated as pattern, slash doesn't need to be escaped
+verify.importFixModuleSpecifiers("", ["ambient"], { autoImportSpecifierExcludeRegexes: ["/.*?$"]});
+// no leading slash, treated as pattern, slash doesn't need to be escaped
+verify.importFixModuleSpecifiers("", ["ambient"], { autoImportSpecifierExcludeRegexes: ["^ambient/"] });
+verify.importFixModuleSpecifiers("", ["ambient/utils"], { autoImportSpecifierExcludeRegexes: ["ambient$"] });
+verify.importFixModuleSpecifiers("", ["ambient", "ambient/utils"], { autoImportSpecifierExcludeRegexes: ["oops("] });
+
+verify.completions({
+  marker: "",
+  includes: [{
+    name: "x",
+    source: "ambient",
+    sourceDisplay: "ambient",
+    hasAction: true,
+    sortText: completion.SortText.AutoImportSuggestions
+  }, {
+    name: "x",
+    source: "ambient/utils",
+    sourceDisplay: "ambient/utils",
+    hasAction: true,
+    sortText: completion.SortText.AutoImportSuggestions
+  }],
+  preferences: {
+    includeCompletionsForModuleExports: true,
+    allowIncompleteCompletions: true
+  }
+});
+
+verify.completions({
+    marker: "",
+    excludes: ["ambient/utils"],
+    preferences: {
+      includeCompletionsForModuleExports: true,
+      allowIncompleteCompletions: true,
+      autoImportSpecifierExcludeRegexes: ["utils"]
+    },
+})
\ No newline at end of file
diff --git a/tests/cases/fourslash/autoImportSpecifierExcludeRegexes2.ts b/tests/cases/fourslash/autoImportSpecifierExcludeRegexes2.ts
new file mode 100644
index 0000000000000..37ab15c5c36b6
--- /dev/null
+++ b/tests/cases/fourslash/autoImportSpecifierExcludeRegexes2.ts
@@ -0,0 +1,25 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: /tsconfig.json
+//// {
+////     "compilerOptions": {
+////         "module": "preserve",
+////         "paths": {
+////             "@app/*": ["./src/*"]
+////         }
+////     }
+//// }
+
+// @Filename: /src/utils.ts
+//// export function add(a: number, b: number) {}
+
+// @Filename: /src/index.ts
+//// add/**/
+
+verify.importFixModuleSpecifiers("", ["./utils"]);
+verify.importFixModuleSpecifiers("", ["@app/utils"], { autoImportSpecifierExcludeRegexes: ["^\\./"] });
+
+verify.importFixModuleSpecifiers("", ["@app/utils"], { importModuleSpecifierPreference: "non-relative" });
+verify.importFixModuleSpecifiers("", ["./utils"], { importModuleSpecifierPreference: "non-relative", autoImportSpecifierExcludeRegexes: ["^@app/"] });
+
+verify.importFixModuleSpecifiers("", [], { autoImportSpecifierExcludeRegexes: ["utils"] });
diff --git a/tests/cases/fourslash/autoImportSpecifierExcludeRegexes3.ts b/tests/cases/fourslash/autoImportSpecifierExcludeRegexes3.ts
new file mode 100644
index 0000000000000..c4cc27c871b34
--- /dev/null
+++ b/tests/cases/fourslash/autoImportSpecifierExcludeRegexes3.ts
@@ -0,0 +1,25 @@
+/// <reference path="fourslash.ts" />
+
+// @module: preserve
+
+// @Filename: /node_modules/pkg/package.json
+//// {
+////     "name": "pkg",
+////     "version": "1.0.0",
+////     "exports": {
+////         ".": "./index.js",
+////         "./utils": "./utils.js"
+////     }
+//// }
+
+// @Filename: /node_modules/pkg/utils.d.ts
+//// export function add(a: number, b: number) {}
+
+// @Filename: /node_modules/pkg/index.d.ts
+//// export * from "./utils";
+
+// @Filename: /src/index.ts
+//// add/**/
+
+verify.importFixModuleSpecifiers("", ["pkg", "pkg/utils"]);
+verify.importFixModuleSpecifiers("", ["pkg/utils"], { autoImportSpecifierExcludeRegexes: ["^pkg$"] });
diff --git a/tests/cases/fourslash/fourslash.ts b/tests/cases/fourslash/fourslash.ts
index c13f27a807ac4..6fa6907a9c0a6 100644
--- a/tests/cases/fourslash/fourslash.ts
+++ b/tests/cases/fourslash/fourslash.ts
@@ -686,6 +686,7 @@ declare namespace FourSlashInterface {
         readonly providePrefixAndSuffixTextForRename?: boolean;
         readonly allowRenameOfImportPath?: boolean;
         readonly autoImportFileExcludePatterns?: readonly string[];
+        readonly autoImportSpecifierExcludeRegexes?: readonly string[];
         readonly preferTypeOnlyAutoImports?: boolean;
         readonly organizeImportsIgnoreCase?: "auto" | boolean;
         readonly organizeImportsCollation?: "unicode" | "ordinal";

From f3b118ed21794eb893c967e28737d2d5f6a08e78 Mon Sep 17 00:00:00 2001
From: Sung Ye In <66503450+syi0808@users.noreply.github.com>
Date: Sat, 10 Aug 2024 05:14:30 +0900
Subject: [PATCH 10/11] fix: filtering promise properties in object literal
 completion (#59316)

---
 src/services/completions.ts                   | 12 ++++++++--
 ...mpletionsPropertiesWithPromiseUnionType.ts | 24 +++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 tests/cases/fourslash/completionsPropertiesWithPromiseUnionType.ts

diff --git a/src/services/completions.ts b/src/services/completions.ts
index ac88e4bf668a5..18fc3e8e5dd59 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -5527,9 +5527,17 @@ function getJsDocTagAtPosition(node: Node, position: number): JSDocTag | undefin
 /** @internal */
 export function getPropertiesForObjectExpression(contextualType: Type, completionsType: Type | undefined, obj: ObjectLiteralExpression | JsxAttributes, checker: TypeChecker): Symbol[] {
     const hasCompletionsType = completionsType && completionsType !== contextualType;
+    const promiseFilteredContextualType = checker.getUnionType(
+        filter(
+            contextualType.flags & TypeFlags.Union ?
+                (contextualType as UnionType).types :
+                [contextualType],
+            t => !checker.getPromisedTypeOfPromise(t),
+        ),
+    );
     const type = hasCompletionsType && !(completionsType.flags & TypeFlags.AnyOrUnknown)
-        ? checker.getUnionType([contextualType, completionsType])
-        : contextualType;
+        ? checker.getUnionType([promiseFilteredContextualType, completionsType])
+        : promiseFilteredContextualType;
 
     const properties = getApparentProperties(type, obj, checker);
     return type.isClass() && containsNonPublicProperties(properties) ? [] :
diff --git a/tests/cases/fourslash/completionsPropertiesWithPromiseUnionType.ts b/tests/cases/fourslash/completionsPropertiesWithPromiseUnionType.ts
new file mode 100644
index 0000000000000..529160b6589b9
--- /dev/null
+++ b/tests/cases/fourslash/completionsPropertiesWithPromiseUnionType.ts
@@ -0,0 +1,24 @@
+/// <reference path="fourslash.ts" />
+// @strict: true
+
+//// type MyType = {
+////   foo: string;
+//// };
+
+//// function fakeTest(cb: () => MyType | Promise<MyType>) {}
+
+//// fakeTest(() => {
+////   return {
+////     /*a*/
+////   };
+//// });
+
+
+verify.completions(
+  {
+    marker: ['a'],
+    exact: [
+      { name: 'foo', kind: 'property' },
+    ]
+  }
+);
\ No newline at end of file

From 4b12d82b6bb4c8e2ad7df3219ae7282e360e62f9 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrewbranch@users.noreply.github.com>
Date: Fri, 9 Aug 2024 13:48:13 -0700
Subject: [PATCH 11/11] Fix auto import file extensions with package.json
 imports wildcards (#59564)

---
 src/compiler/moduleSpecifiers.ts              | 72 +++++++++++++++----
 src/compiler/utilities.ts                     |  7 ++
 ...mportingTsExtensionsPackageJsonImports1.ts | 41 +++++++++++
 ...mportingTsExtensionsPackageJsonImports2.ts | 34 +++++++++
 ...ImportPackageJsonImportsCaseSensitivity.ts | 20 ++++++
 5 files changed, 161 insertions(+), 13 deletions(-)
 create mode 100644 tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports1.ts
 create mode 100644 tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports2.ts
 create mode 100644 tests/cases/fourslash/autoImportPackageJsonImportsCaseSensitivity.ts

diff --git a/src/compiler/moduleSpecifiers.ts b/src/compiler/moduleSpecifiers.ts
index f193aeb6784f1..4b7cbf2bae274 100644
--- a/src/compiler/moduleSpecifiers.ts
+++ b/src/compiler/moduleSpecifiers.ts
@@ -4,6 +4,7 @@ import {
     AmbientModuleDeclaration,
     append,
     arrayFrom,
+    changeFullExtension,
     CharacterCodes,
     combinePaths,
     compareBooleans,
@@ -59,6 +60,7 @@ import {
     getSupportedExtensions,
     getTemporaryModuleResolutionState,
     getTextOfIdentifierOrLiteral,
+    hasImplementationTSFileExtension,
     hasJSFileExtension,
     hasTSFileExtension,
     hostGetCanonicalFileName,
@@ -599,7 +601,16 @@ function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOpt
         return pathsOnly ? undefined : relativePath;
     }
 
-    const fromPackageJsonImports = pathsOnly ? undefined : tryGetModuleNameFromPackageJsonImports(moduleFileName, sourceDirectory, compilerOptions, host, importMode);
+    const fromPackageJsonImports = pathsOnly
+        ? undefined
+        : tryGetModuleNameFromPackageJsonImports(
+            moduleFileName,
+            sourceDirectory,
+            compilerOptions,
+            host,
+            importMode,
+            prefersTsExtension(allowedEndings),
+        );
 
     const fromPaths = pathsOnly || fromPackageJsonImports === undefined ? paths && tryGetModuleNameFromPaths(relativeToBaseUrl, paths, allowedEndings, host, compilerOptions) : undefined;
     if (pathsOnly) {
@@ -997,7 +1008,18 @@ const enum MatchingMode {
     Pattern,
 }
 
-function tryGetModuleNameFromExportsOrImports(options: CompilerOptions, host: ModuleSpecifierResolutionHost, targetFilePath: string, packageDirectory: string, packageName: string, exports: unknown, conditions: string[], mode: MatchingMode, isImports: boolean): { moduleFileToTry: string; } | undefined {
+function tryGetModuleNameFromExportsOrImports(
+    options: CompilerOptions,
+    host: ModuleSpecifierResolutionHost,
+    targetFilePath: string,
+    packageDirectory: string,
+    packageName: string,
+    exports: unknown,
+    conditions: string[],
+    mode: MatchingMode,
+    isImports: boolean,
+    preferTsExtension: boolean,
+): { moduleFileToTry: string; } | undefined {
     if (typeof exports === "string") {
         const ignoreCase = !hostUsesCaseSensitiveFileNames(host);
         const getCommonSourceDirectory = () => host.getCommonSourceDirectory();
@@ -1006,6 +1028,7 @@ function tryGetModuleNameFromExportsOrImports(options: CompilerOptions, host: Mo
 
         const pathOrPattern = getNormalizedAbsolutePath(combinePaths(packageDirectory, exports), /*currentDirectory*/ undefined);
         const extensionSwappedTarget = hasTSFileExtension(targetFilePath) ? removeFileExtension(targetFilePath) + tryGetJSExtensionForFile(targetFilePath, options) : undefined;
+        const canTryTsExtension = preferTsExtension && hasImplementationTSFileExtension(targetFilePath);
 
         switch (mode) {
             case MatchingMode.Exact:
@@ -1019,11 +1042,15 @@ function tryGetModuleNameFromExportsOrImports(options: CompilerOptions, host: Mo
                 }
                 break;
             case MatchingMode.Directory:
+                if (canTryTsExtension && containsPath(targetFilePath, pathOrPattern, ignoreCase)) {
+                    const fragment = getRelativePathFromDirectory(pathOrPattern, targetFilePath, /*ignoreCase*/ false);
+                    return { moduleFileToTry: getNormalizedAbsolutePath(combinePaths(combinePaths(packageName, exports), fragment), /*currentDirectory*/ undefined) };
+                }
                 if (extensionSwappedTarget && containsPath(pathOrPattern, extensionSwappedTarget, ignoreCase)) {
                     const fragment = getRelativePathFromDirectory(pathOrPattern, extensionSwappedTarget, /*ignoreCase*/ false);
                     return { moduleFileToTry: getNormalizedAbsolutePath(combinePaths(combinePaths(packageName, exports), fragment), /*currentDirectory*/ undefined) };
                 }
-                if (containsPath(pathOrPattern, targetFilePath, ignoreCase)) {
+                if (!canTryTsExtension && containsPath(pathOrPattern, targetFilePath, ignoreCase)) {
                     const fragment = getRelativePathFromDirectory(pathOrPattern, targetFilePath, /*ignoreCase*/ false);
                     return { moduleFileToTry: getNormalizedAbsolutePath(combinePaths(combinePaths(packageName, exports), fragment), /*currentDirectory*/ undefined) };
                 }
@@ -1032,7 +1059,7 @@ function tryGetModuleNameFromExportsOrImports(options: CompilerOptions, host: Mo
                     return { moduleFileToTry: combinePaths(packageName, fragment) };
                 }
                 if (declarationFile && containsPath(pathOrPattern, declarationFile, ignoreCase)) {
-                    const fragment = getRelativePathFromDirectory(pathOrPattern, declarationFile, /*ignoreCase*/ false);
+                    const fragment = changeFullExtension(getRelativePathFromDirectory(pathOrPattern, declarationFile, /*ignoreCase*/ false), getJSExtensionForFile(declarationFile, options));
                     return { moduleFileToTry: combinePaths(packageName, fragment) };
                 }
                 break;
@@ -1040,11 +1067,15 @@ function tryGetModuleNameFromExportsOrImports(options: CompilerOptions, host: Mo
                 const starPos = pathOrPattern.indexOf("*");
                 const leadingSlice = pathOrPattern.slice(0, starPos);
                 const trailingSlice = pathOrPattern.slice(starPos + 1);
+                if (canTryTsExtension && startsWith(targetFilePath, leadingSlice, ignoreCase) && endsWith(targetFilePath, trailingSlice, ignoreCase)) {
+                    const starReplacement = targetFilePath.slice(leadingSlice.length, targetFilePath.length - trailingSlice.length);
+                    return { moduleFileToTry: replaceFirstStar(packageName, starReplacement) };
+                }
                 if (extensionSwappedTarget && startsWith(extensionSwappedTarget, leadingSlice, ignoreCase) && endsWith(extensionSwappedTarget, trailingSlice, ignoreCase)) {
                     const starReplacement = extensionSwappedTarget.slice(leadingSlice.length, extensionSwappedTarget.length - trailingSlice.length);
                     return { moduleFileToTry: replaceFirstStar(packageName, starReplacement) };
                 }
-                if (startsWith(targetFilePath, leadingSlice, ignoreCase) && endsWith(targetFilePath, trailingSlice, ignoreCase)) {
+                if (!canTryTsExtension && startsWith(targetFilePath, leadingSlice, ignoreCase) && endsWith(targetFilePath, trailingSlice, ignoreCase)) {
                     const starReplacement = targetFilePath.slice(leadingSlice.length, targetFilePath.length - trailingSlice.length);
                     return { moduleFileToTry: replaceFirstStar(packageName, starReplacement) };
                 }
@@ -1054,20 +1085,22 @@ function tryGetModuleNameFromExportsOrImports(options: CompilerOptions, host: Mo
                 }
                 if (declarationFile && startsWith(declarationFile, leadingSlice, ignoreCase) && endsWith(declarationFile, trailingSlice, ignoreCase)) {
                     const starReplacement = declarationFile.slice(leadingSlice.length, declarationFile.length - trailingSlice.length);
-                    return { moduleFileToTry: replaceFirstStar(packageName, starReplacement) };
+                    const substituted = replaceFirstStar(packageName, starReplacement);
+                    const jsExtension = tryGetJSExtensionForFile(declarationFile, options);
+                    return jsExtension ? { moduleFileToTry: changeFullExtension(substituted, jsExtension) } : undefined;
                 }
                 break;
         }
     }
     else if (Array.isArray(exports)) {
-        return forEach(exports, e => tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, packageName, e, conditions, mode, isImports));
+        return forEach(exports, e => tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, packageName, e, conditions, mode, isImports, preferTsExtension));
     }
     else if (typeof exports === "object" && exports !== null) { // eslint-disable-line no-restricted-syntax
         // conditional mapping
         for (const key of getOwnKeys(exports as MapLike<unknown>)) {
             if (key === "default" || conditions.indexOf(key) >= 0 || isApplicableVersionedTypesKey(conditions, key)) {
                 const subTarget = (exports as MapLike<unknown>)[key];
-                const result = tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, packageName, subTarget, conditions, mode, isImports);
+                const result = tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, packageName, subTarget, conditions, mode, isImports, preferTsExtension);
                 if (result) {
                     return result;
                 }
@@ -1089,13 +1122,13 @@ function tryGetModuleNameFromExports(options: CompilerOptions, host: ModuleSpeci
             const mode = endsWith(k, "/") ? MatchingMode.Directory
                 : k.includes("*") ? MatchingMode.Pattern
                 : MatchingMode.Exact;
-            return tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, subPackageName, (exports as MapLike<unknown>)[k], conditions, mode, /*isImports*/ false);
+            return tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, subPackageName, (exports as MapLike<unknown>)[k], conditions, mode, /*isImports*/ false, /*preferTsExtension*/ false);
         });
     }
-    return tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, packageName, exports, conditions, MatchingMode.Exact, /*isImports*/ false);
+    return tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, packageName, exports, conditions, MatchingMode.Exact, /*isImports*/ false, /*preferTsExtension*/ false);
 }
 
-function tryGetModuleNameFromPackageJsonImports(moduleFileName: string, sourceDirectory: string, options: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode) {
+function tryGetModuleNameFromPackageJsonImports(moduleFileName: string, sourceDirectory: string, options: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, preferTsExtension: boolean) {
     if (!host.readFile || !getResolvePackageJsonImports(options)) {
         return undefined;
     }
@@ -1120,7 +1153,7 @@ function tryGetModuleNameFromPackageJsonImports(moduleFileName: string, sourceDi
         const mode = endsWith(k, "/") ? MatchingMode.Directory
             : k.includes("*") ? MatchingMode.Pattern
             : MatchingMode.Exact;
-        return tryGetModuleNameFromExportsOrImports(options, host, moduleFileName, ancestorDirectoryWithPackageJson, k, (imports as MapLike<unknown>)[k], conditions, mode, /*isImports*/ true);
+        return tryGetModuleNameFromExportsOrImports(options, host, moduleFileName, ancestorDirectoryWithPackageJson, k, (imports as MapLike<unknown>)[k], conditions, mode, /*isImports*/ true, preferTsExtension);
     })?.moduleFileToTry;
 }
 
@@ -1221,7 +1254,15 @@ function tryGetModuleNameAsNodeModule({ path, isRedirect }: ModulePath, { getCan
                 const packageName = getPackageNameFromTypesPackageName(nodeModulesDirectoryName);
                 const conditions = getConditions(options, importMode);
                 const fromExports = packageJsonContent?.exports
-                    ? tryGetModuleNameFromExports(options, host, path, packageRootPath, packageName, packageJsonContent.exports, conditions)
+                    ? tryGetModuleNameFromExports(
+                        options,
+                        host,
+                        path,
+                        packageRootPath,
+                        packageName,
+                        packageJsonContent.exports,
+                        conditions,
+                    )
                     : undefined;
                 if (fromExports) {
                     return { ...fromExports, verbatimFromExports: true };
@@ -1411,3 +1452,8 @@ function isPathRelativeToParent(path: string): boolean {
 function getDefaultResolutionModeForFile(file: Pick<SourceFile, "fileName" | "impliedNodeFormat" | "packageJsonScope">, host: Pick<ModuleSpecifierResolutionHost, "getDefaultResolutionModeForFile">, compilerOptions: CompilerOptions) {
     return isFullSourceFile(file) ? host.getDefaultResolutionModeForFile(file) : getDefaultResolutionModeForFileWorker(file, compilerOptions);
 }
+
+function prefersTsExtension(allowedEndings: readonly ModuleSpecifierEnding[]) {
+    const tsPriority = allowedEndings.indexOf(ModuleSpecifierEnding.TsExtension);
+    return tsPriority > -1 && tsPriority < allowedEndings.indexOf(ModuleSpecifierEnding.JsExtension);
+}
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index b7600682b6ca2..2c647c697c4cf 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -265,6 +265,7 @@ import {
     isConstructorDeclaration,
     isConstTypeReference,
     isDeclaration,
+    isDeclarationFileName,
     isDecorator,
     isElementAccessExpression,
     isEnumDeclaration,
@@ -9785,6 +9786,12 @@ export function hasTSFileExtension(fileName: string): boolean {
     return some(supportedTSExtensionsFlat, extension => fileExtensionIs(fileName, extension));
 }
 
+/** @internal */
+export function hasImplementationTSFileExtension(fileName: string): boolean {
+    return some(supportedTSImplementationExtensions, extension => fileExtensionIs(fileName, extension))
+        && !isDeclarationFileName(fileName);
+}
+
 /**
  * @internal
  * Corresponds to UserPreferences#importPathEnding
diff --git a/tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports1.ts b/tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports1.ts
new file mode 100644
index 0000000000000..8db0bdb37d552
--- /dev/null
+++ b/tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports1.ts
@@ -0,0 +1,41 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+// @allowImportingTsExtensions: true
+
+// @Filename: /node_modules/pkg/package.json
+//// {
+////   "name": "pkg",
+////   "type": "module",
+////   "exports": {
+////     "./*": {
+////       "types": "./types/*",
+////       "default": "./dist/*"
+////     }
+////   }
+//// }
+
+// @Filename: /node_modules/pkg/types/external.d.ts
+//// export declare function external(name: string): any;
+
+// @Filename: /package.json
+//// {
+////   "name": "self",
+////   "type": "module",
+////   "imports": {
+////     "#*": "./src/*"
+////   },
+////   "dependencies": {
+////     "pkg": "*"
+////   }
+//// }
+
+// @Filename: /src/add.ts
+//// export function add(a: number, b: number) {}
+
+// @Filename: /src/index.ts
+//// add/*imports*/;
+//// external/*exports*/;
+
+verify.importFixModuleSpecifiers("imports", ["#add.ts"]);
+verify.importFixModuleSpecifiers("exports", ["pkg/external.js"]);
diff --git a/tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports2.ts b/tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports2.ts
new file mode 100644
index 0000000000000..c5e9938747782
--- /dev/null
+++ b/tests/cases/fourslash/autoImportAllowImportingTsExtensionsPackageJsonImports2.ts
@@ -0,0 +1,34 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: /tsconfig.json
+//// {
+////   "compilerOptions": {
+////     "module": "nodenext",
+////     "allowImportingTsExtensions": true,
+////     "rootDir": "src",
+////     "outDir": "dist",
+////     "declarationDir": "types",
+////     "declaration": true
+////   }
+//// }
+
+// @Filename: /package.json
+//// {
+////   "name": "self",
+////   "type": "module",
+////   "imports": {
+////     "#*": {
+////       "types": "./types/*",
+////       "default": "./dist/*"
+////     }
+////   }
+//// }
+
+// @Filename: /src/add.ts
+//// export function add(a: number, b: number) {}
+
+// @Filename: /src/index.ts
+//// add/*imports*/;
+//// external/*exports*/;
+
+verify.importFixModuleSpecifiers("imports", ["#add.js"]);
diff --git a/tests/cases/fourslash/autoImportPackageJsonImportsCaseSensitivity.ts b/tests/cases/fourslash/autoImportPackageJsonImportsCaseSensitivity.ts
new file mode 100644
index 0000000000000..79d62ec33ced0
--- /dev/null
+++ b/tests/cases/fourslash/autoImportPackageJsonImportsCaseSensitivity.ts
@@ -0,0 +1,20 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+// @allowImportingTsExtensions: true
+
+// @Filename: /package.json
+//// {
+////   "type": "module",
+////   "imports": {
+////     "#src/*": "./SRC/*"
+////   }
+//// }
+
+// @Filename: /src/add.ts
+//// export function add(a: number, b: number) {}
+
+// @Filename: /src/index.ts
+//// add/*imports*/;
+
+verify.importFixModuleSpecifiers("imports", ["#src/add.ts"], { importModuleSpecifierPreference: "non-relative" });
\ No newline at end of file