fixed covariant mapping value type used in overload

stdlib/@tests/stubtest_allowlists/py313.txt

@@ -105,9 +105,6 @@ multiprocessing.managers._BaseDictProxy.keys
 multiprocessing.managers._BaseDictProxy.popitem
 multiprocessing.managers._BaseDictProxy.values
 
-# To match `dict`, we lie about the runtime, but use overloads to match the correct behavior
-types.MappingProxyType.get
-
 typing_extensions.Protocol  # Super-special typing primitive
 
 

stdlib/@tests/stubtest_allowlists/py314.txt

@@ -139,9 +139,6 @@ multiprocessing.managers._BaseDictProxy.keys
 multiprocessing.managers._BaseDictProxy.popitem
 multiprocessing.managers._BaseDictProxy.values
 
-# To match `dict`, we lie about the runtime, but use overloads to match the correct behavior
-types.MappingProxyType.get
-
 typing_extensions.Protocol  # Super-special typing primitive
 
 

stdlib/@tests/test_cases/builtins/check_dict.py

@@ -71,34 +71,35 @@ def test_iterable_tuple_overload(x: Iterable[tuple[int, str]]) -> dict[int, str]
 int_value = 1
 
 assert_type(d_any["key"], Any)
-assert_type(d_any.get("key"), Union[Any, None])
-assert_type(d_any.get("key", None), Union[Any, None])
+assert_type(d_any.get("key"), Any | None)
+assert_type(d_any.get("key", None), Any | None)
 assert_type(d_any.get("key", any_value), Any)
-assert_type(d_any.get("key", str_value), Any)
-assert_type(d_any.get("key", int_value), Any)
+assert_type(d_any.get("key", str_value), Any | str)
+assert_type(d_any.get("key", int_value), Any | int)
 
 assert_type(d_str["key"], str)
-assert_type(d_str.get("key"), Union[str, None])
-assert_type(d_str.get("key", None), Union[str, None])
+assert_type(d_str.get("key"), str | None)
+assert_type(d_str.get("key", None), str | None)
 # Pyright has str instead of Any here
-assert_type(d_str.get("key", any_value), Any)  # pyright: ignore[reportAssertTypeFailure]
+assert_type(d_str.get("key", any_value), str | Any)
 assert_type(d_str.get("key", str_value), str)
-assert_type(d_str.get("key", int_value), Union[str, int])
+assert_type(d_str.get("key", int_value), str | int)
 
 # Now with context!
+# Note: One would expect 'assignment' rather than 'arg-type' error code,
+#  but this is a bug in mypy (https://github.com/python/mypy/issues/20576)
 result: str
 result = d_any["key"]
 result = d_any.get("key")  # type: ignore[assignment]
-result = d_any.get("key", None)  # type: ignore[assignment]
+result = d_any.get("key", None)  # type: ignore[arg-type]
 result = d_any.get("key", any_value)
 result = d_any.get("key", str_value)
-result = d_any.get("key", int_value)
+result = d_any.get("key", int_value)  # type: ignore[arg-type]
 
 result = d_str["key"]
 result = d_str.get("key")  # type: ignore[assignment]
-result = d_str.get("key", None)  # type: ignore[assignment]
-# Pyright has str | None here, see https://github.com/microsoft/pyright/discussions/9570
-result = d_str.get("key", any_value)  # pyright: ignore[reportAssignmentType]
+result = d_str.get("key", None)  # type: ignore[arg-type]
+result = d_str.get("key", any_value)
 result = d_str.get("key", str_value)
 result = d_str.get("key", int_value)  # type: ignore[arg-type]
 
@@ -140,11 +141,15 @@ def test8() -> str:
 
 
 def test9() -> str:
-    return d_str.get("key", None)  # type: ignore[return-value]
+    # Note: One would expect 'return-value' rather than 'arg-type' error code,
+    #  but this is a bug in mypy (https://github.com/python/mypy/issues/20576)
+    return d_str.get("key", None)  # type: ignore[arg-type]
 
 
-def test10() -> str:
-    return d_str.get("key", any_value)  # type: ignore[no-any-return]
+# Pyright doesn't have a version of no-any-return,
+# and mypy doesn't have a type: ignore that pyright will ignore.
+# def test10() -> str:
+#     return d_str.get("key", any_value)  # mypy: ignore[no-any-return]
 
 
 def test11() -> str:

stdlib/builtins.pyi

@@ -1232,9 +1232,7 @@ class dict(MutableMapping[_KT, _VT]):
     def fromkeys(cls, iterable: Iterable[_T], value: _S, /) -> dict[_T, _S]: ...
     # Positional-only in dict, but not in MutableMapping
     @overload  # type: ignore[override]
-    def get(self, key: _KT, default: None = None, /) -> _VT | None: ...
-    @overload
-    def get(self, key: _KT, default: _VT, /) -> _VT: ...
+    def get(self, key: _KT, /) -> _VT | None: ...
     @overload
     def get(self, key: _KT, default: _T, /) -> _VT | _T: ...
     @overload

stdlib/collections/__init__.pyi

@@ -105,9 +105,7 @@ class UserDict(MutableMapping[_KT, _VT]):
     def __ior__(self, other: Iterable[tuple[_KT, _VT]]) -> Self: ...
     if sys.version_info >= (3, 12):
         @overload
-        def get(self, key: _KT, default: None = None) -> _VT | None: ...
-        @overload
-        def get(self, key: _KT, default: _VT) -> _VT: ...
+        def get(self, key: _KT) -> _VT | None: ...
         @overload
         def get(self, key: _KT, default: _T) -> _VT | _T: ...
 
@@ -473,9 +471,7 @@ class ChainMap(MutableMapping[_KT, _VT]):
     def __len__(self) -> int: ...
     def __contains__(self, key: object) -> bool: ...
     @overload
-    def get(self, key: _KT, default: None = None) -> _VT | None: ...
-    @overload
-    def get(self, key: _KT, default: _VT) -> _VT: ...
+    def get(self, key: _KT) -> _VT | None: ...
     @overload
     def get(self, key: _KT, default: _T) -> _VT | _T: ...
     def __missing__(self, key: _KT) -> _VT: ...  # undocumented

stdlib/importlib/metadata/__init__.pyi

@@ -163,9 +163,7 @@ if sys.version_info < (3, 12):
     class Deprecated(Generic[_KT, _VT]):
         def __getitem__(self, name: _KT) -> _VT: ...
         @overload
-        def get(self, name: _KT, default: None = None) -> _VT | None: ...
-        @overload
-        def get(self, name: _KT, default: _VT) -> _VT: ...
+        def get(self, name: _KT) -> _VT | None: ...
         @overload
         def get(self, name: _KT, default: _T) -> _VT | _T: ...
         def __iter__(self) -> Iterator[_KT]: ...

stdlib/os/__init__.pyi

@@ -715,9 +715,7 @@ class _Environ(MutableMapping[AnyStr, AnyStr], Generic[AnyStr]):
         decodevalue: _EnvironCodeFunc[AnyStr],
     ) -> None: ...
     @overload
-    def get(self, key: AnyStr, default: None = None) -> AnyStr | None: ...
-    @overload
-    def get(self, key: AnyStr, default: AnyStr) -> AnyStr: ...
+    def get(self, key: AnyStr) -> AnyStr | None: ...
     @overload
     def get(self, key: AnyStr, default: _T) -> AnyStr | _T: ...
     @overload

stdlib/types.pyi

@@ -281,8 +281,6 @@ class MappingProxyType(Mapping[_KT_co, _VT_co]):  # type: ignore[type-var]  # py
     @overload
     def get(self, key: _KT_co, /) -> _VT_co | None: ...  # type: ignore[misc]  # pyright: ignore[reportGeneralTypeIssues] # Covariant type as parameter
     @overload
-    def get(self, key: _KT_co, default: _VT_co, /) -> _VT_co: ...  # type: ignore[misc] # pyright: ignore[reportGeneralTypeIssues] # Covariant type as parameter
-    @overload
     def get(self, key: _KT_co, default: _T2, /) -> _VT_co | _T2: ...  # type: ignore[misc]  # pyright: ignore[reportGeneralTypeIssues] # Covariant type as parameter
     def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
     def __reversed__(self) -> Iterator[_KT_co]: ...

stdlib/typing.pyi

@@ -799,8 +799,6 @@ class Mapping(Collection[_KT], Generic[_KT, _VT_co]):
     @overload
     def get(self, key: _KT, /) -> _VT_co | None: ...
     @overload
-    def get(self, key: _KT, default: _VT_co, /) -> _VT_co: ...  # type: ignore[misc] # pyright: ignore[reportGeneralTypeIssues] # Covariant type as parameter
-    @overload
     def get(self, key: _KT, default: _T, /) -> _VT_co | _T: ...
     def items(self) -> ItemsView[_KT, _VT_co]: ...
     def keys(self) -> KeysView[_KT]: ...

stdlib/weakref.pyi

@@ -99,9 +99,7 @@ class WeakValueDictionary(MutableMapping[_KT, _VT]):
     __copy__ = copy
     def __deepcopy__(self, memo: Any) -> Self: ...
     @overload
-    def get(self, key: _KT, default: None = None) -> _VT | None: ...
-    @overload
-    def get(self, key: _KT, default: _VT) -> _VT: ...
+    def get(self, key: _KT) -> _VT | None: ...
     @overload
     def get(self, key: _KT, default: _T) -> _VT | _T: ...
     # These are incompatible with Mapping
@@ -152,9 +150,7 @@ class WeakKeyDictionary(MutableMapping[_KT, _VT]):
     __copy__ = copy
     def __deepcopy__(self, memo: Any) -> Self: ...
     @overload
-    def get(self, key: _KT, default: None = None) -> _VT | None: ...
-    @overload
-    def get(self, key: _KT, default: _VT) -> _VT: ...
+    def get(self, key: _KT) -> _VT | None: ...
     @overload
     def get(self, key: _KT, default: _T) -> _VT | _T: ...
     # These are incompatible with Mapping

stubs/WebOb/webob/cookies.pyi

@@ -35,9 +35,7 @@ class RequestCookies(MutableMapping[str, str]):
     def __setitem__(self, name: str, value: str) -> None: ...
     def __getitem__(self, name: str) -> str: ...
     @overload
-    def get(self, name: str, default: None = None) -> str | None: ...
-    @overload
-    def get(self, name: str, default: str) -> str: ...
+    def get(self, name: str) -> str | None: ...
     @overload
     def get(self, name: str, default: _T) -> str | _T: ...
     def __delitem__(self, name: str) -> None: ...

stubs/WebOb/webob/multidict.pyi

@@ -49,9 +49,7 @@ class MultiDict(MutableMapping[_KT, _VT]):
     def __setitem__(self, key: _KT, value: _VT) -> None: ...
     def add(self, key: _KT, value: _VT) -> None: ...
     @overload
-    def get(self, key: _KT, default: None = None) -> _VT | None: ...
-    @overload
-    def get(self, key: _KT, default: _VT) -> _VT: ...
+    def get(self, key: _KT) -> _VT | None: ...
     @overload
     def get(self, key: _KT, default: _T) -> _VT | _T: ...
     def getall(self, key: _KT) -> list[_VT]: ...

stubs/boltons/boltons/cacheutils.pyi

@@ -24,11 +24,9 @@ class LRI(dict[_KT, _VT]):
     def __setitem__(self, key: _KT, value: _VT) -> None: ...
     def __getitem__(self, key: _KT) -> _VT: ...
     @overload
-    def get(self, key: _KT, default: None = None) -> _VT | None: ...
+    def get(self, key: _KT) -> _VT | None: ...
     @overload
-    def get(self, key: _KT, default: _VT) -> _VT: ...
-    @overload
-    def get(self, key: _KT, default: _T) -> _T | _VT: ...
+    def get(self, key: _KT, default: _T) -> _VT | _T: ...
     def __delitem__(self, key: _KT) -> None: ...
     @overload
     def pop(self, key: _KT) -> _VT: ...

stubs/grpcio/grpc/aio/__init__.pyi

@@ -454,9 +454,7 @@ class Metadata(Mapping[_MetadataKey, _MetadataValue]):
     def delete_all(self, key: _MetadataKey) -> None: ...
     def __iter__(self) -> Iterator[_MetadataKey]: ...
     @overload
-    def get(self, key: _MetadataKey, default: None = None) -> _MetadataValue | None: ...
-    @overload
-    def get(self, key: _MetadataKey, default: _MetadataValue) -> _MetadataValue: ...
+    def get(self, key: _MetadataKey) -> _MetadataValue | None: ...
     @overload
     def get(self, key: _MetadataKey, default: _T) -> _MetadataValue | _T: ...
     def get_all(self, key: _MetadataKey) -> list[_MetadataValue]: ...

stubs/inifile/inifile.pyi

@@ -68,9 +68,7 @@ class IniData(MutableMapping[str, str]):
     def to_dict(self) -> dict[str, str]: ...
     def __len__(self) -> int: ...
     @overload
-    def get(self, name: str, default: None = None) -> str | None: ...
-    @overload
-    def get(self, name: str, default: str) -> str: ...
+    def get(self, name: str) -> str | None: ...
     @overload
     def get(self, name: str, default: _T) -> str | _T: ...
     @overload

stubs/protobuf/google/protobuf/internal/containers.pyi

@@ -78,9 +78,7 @@ class ScalarMap(MutableMapping[_K, _ScalarV]):
     ) -> None: ...
     def __getitem__(self, key: _K) -> _ScalarV: ...
     @overload
-    def get(self, key: _K, default: None = None) -> _ScalarV | None: ...
-    @overload
-    def get(self, key: _K, default: _ScalarV) -> _ScalarV: ...
+    def get(self, key: _K) -> _ScalarV | None: ...
     @overload
     def get(self, key: _K, default: _T) -> _ScalarV | _T: ...
     def __setitem__(self, key: _K, value: _ScalarV) -> None: ...
@@ -106,9 +104,7 @@ class MessageMap(MutableMapping[_K, _MessageV]):
     def __getitem__(self, key: _K) -> _MessageV: ...
     def get_or_create(self, key: _K) -> _MessageV: ...
     @overload
-    def get(self, key: _K, default: None = None) -> _MessageV | None: ...
-    @overload
-    def get(self, key: _K, default: _MessageV) -> _MessageV: ...
+    def get(self, key: _K) -> _MessageV | None: ...
     @overload
     def get(self, key: _K, default: _T) -> _MessageV | _T: ...
     def __setitem__(self, key: _K, value: _MessageV) -> None: ...

stubs/setuptools/setuptools/__init__.pyi

@@ -38,6 +38,7 @@ _CommandT = TypeVar("_CommandT", bound=_Command)
 _DistributionT = TypeVar("_DistributionT", bound=_Distribution, default=Distribution)
 _KT = TypeVar("_KT")
 _VT_co = TypeVar("_VT_co", covariant=True)
+_T = TypeVar("_T")
 
 __all__ = [
     "setup",
@@ -58,7 +59,10 @@ __version__: str
 @type_check_only
 class _DictLike(Protocol[_KT, _VT_co]):
     # See note about using _VT_co instead of Any
-    def get(self, key: _KT, default: Any | None = None, /) -> _VT_co | None: ...
+    @overload
+    def get(self, key: _KT, /) -> _VT_co | None: ...
+    @overload
+    def get(self, key: _KT, default: _T, /) -> _VT_co | _T: ...
     def items(self) -> ItemsView[_KT, _VT_co]: ...
     def keys(self) -> Iterable[_KT]: ...
     def __getitem__(self, key: _KT, /) -> _VT_co: ...