[Clang] Comparison between pointers to a string literal and some other object results in constant evaluation failure

[frederick-vs-ja]

The following code snippet is incorrectly rejected by Clang (Godbolt link).

static_assert([]{
    char arr[1]{};
    return arr != "a";
}());

arr is not a potentially non-unique object, so it must have a different address from that of string literal object "a", even though the latte is a potentially non-unique object. As a result, arr != "a" has a specified result (true), so the static assertion should be accepted.

#49380 is related. But that issue involved comparison between pointers to different string literal objects, where it's very non-trivial to determine whether the result is unspecified.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: A. Jiang (frederick-vs-ja)

The following code snippet is incorrectly rejected by Clang ([Godbolt link](https://godbolt.org/z/sYcjG6aTP)).

static_assert([]{
    char arr[1]{};
    return arr != "a";
}());

arr is not a potentially non-unique object, so it must have a different address from that of string literal object "a", even though the latte is a potentially non-unique object. As a result, arr != "a" has a specified result (true), so the static assertion should be accepted.

#49380 is related. But that issue involved comparison between pointers to different string literal objects, where it's very non-trivial to determine whether the result is unspecified.