gnu extension "?:" with enums not faithful

[ggreif]

Bugzilla Link	15626
Version	trunk
OS	All
CC	@DougGregor

Extended Description

$ clang gnutest.cc gnutest.cc:7:10: error: cannot initialize return object of type 'Howdy' with an rvalue of type 'int' return you ?: Hi; ^~~~~ 1 error generated.

This works nicely with g++ (v3.4 and v4.4). I guess clang models this as

int temp = you; return temp ? temp : Hi;

while g++ does:

Howdy temp = you; return temp ? temp : Hi;

The test program is:

$ cat gnutest.cc

enum Howdy {
  Lo, Hi 
};

Howdy test(Howdy you)
{
  return you ?: Hi;
}

[ggreif]

This is in 3.4 still.

Btw. is there an official translation of the binary operator to the ternary one? How does GCC do it?

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Gabor Greif (ggreif)

| | | | --- | --- | | Bugzilla Link | [15626](https://llvm.org/bz15626) | | Version | trunk | | OS | All | | CC | @DougGregor | ## Extended Description $ clang gnutest.cc gnutest.cc:7:10: error: cannot initialize return object of type 'Howdy' with an rvalue of type 'int' return you ?: Hi; ^~~~~~~~~ 1 error generated. This works nicely with g++ (v3.4 and v4.4). I guess clang models this as > int temp = you; > return temp ? temp : Hi; while g++ does: > Howdy temp = you; > return temp ? temp : Hi; The test program is: `$ cat gnutest.cc` ```cpp enum Howdy { Lo, Hi }; Howdy test(Howdy you) { return you ?: Hi; } ```

[shafik]

CC @zygoloid any pointers here, I think we want to remain compatible. I guess we need to fix something in Sema::CXXCheckConditionalOperands