[Clang][C23] Compound literal with `constexpr` (or any other) storage specifier emits syntax error

[euclidianAce]

I couldn't find a specific issue on this, but it is part of C23. See 6.5.3.6p7 and 6.6.3p6

Simple repro

int main() {
	int x = (constexpr int){1};
}

$ clang repro.c -std=c23 -Wall -Wextra -pedantic
repro.c:2:11: error: expected expression
    2 |         int x = (constexpr int){1};
      |                  ^
1 error generated.

$ clang --version
clang version 19.1.7
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /nix/store/azdqrk7n19ipjh2yav5kllzll7a49phn-clang-19.1.7/bin

Looking through clang/test/Sema/constexpr.c this case wasn't covered

[frederick-vs-ja]

This feature (N3038) is not implemented yet, see https://clang.llvm.org/c_status.html.

#65190 talked about this.

I guess we can keep this issue open until the feature gets implemented.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: None (euclidianAce)

I couldn't find a specific issue on this, but it is part of C23. See `6.5.3.6p7` and `6.6.3p6`

Simple repro

int main() {
	int x = (constexpr int){1};
}

$ clang repro.c -std=c23 -Wall -Wextra -pedantic
repro.c:2:11: error: expected expression
    2 |         int x = (constexpr int){1};
      |                  ^
1 error generated.

$ clang --version
clang version 19.1.7
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /nix/store/azdqrk7n19ipjh2yav5kllzll7a49phn-clang-19.1.7/bin

Looking through clang/test/Sema/constexpr.c this case wasn't covered