References

[jmafc]

Is there a way of declaring plain reference variables in CPP2? e.g.,

int foo = 10;
int& bar = foo;

I tried bar: i32& = foo; but got error: missing semicolon at end of declaration or equal at start of initializer (at '&')

[AbhinavK00]

Cppfront intends to do away with references completely. The basic guideline is to use pointers instead. If you do want refereces, you will have to use cpp style syntax.

[jmafc]

Ok, but if I say bar: *i32 = foo&;, the generated cpp is a raw pointer, which is very counter-intuitive, since we've been told countless times "raw pointers are unsafe, use smart pointers instead", yet cppfront says all Cpp2, passes safety checks.

I see also that if I try to change bar, e.g., bar* = 42; (I have to remember it's a pointer and dereference it, cppfront does catch that) and the generated code is *cpp2::assert_not_null(bar) = 42; which presumably will give an exception and terminate if bar is somehow disconnected from foo. Is that the safety guarantee?

[AbhinavK00]

since we've been told countless times "raw pointers are unsafe, use smart pointers instead",

That's not fully correct. Use smart pointers when you have to manage ownership, non-owning pointers are fine (as long as they don't outlive the owner).

[JohelEGP]

You can use a parameterized statement to the same effect (https://cpp2.godbolt.org/z/dqPaTP55W):

main: () = {
  i := 0;
  (inout j := i) {
    [[assert: i& == j&]]
  }
}

[jmafc]

Is the "Pascal/Go"ish := the equivalent of auto? Is this described somewhere other than examples? (Admittedly, I haven't watched all of the talks or looked at all the regression tests).

[JohelEGP]

See #386 (comment).

[JohelEGP]

x := 0; is a shorthand for
x: _ = 0;,
where _ is the unconstrained placeholder "auto", if that makes sense.