Clang accepts invalid identifiers in [[gnu::abi_tag]]

[philnik777]

Currently clang accepts code like [[gnu::abi_tag("123")]] void func() {}. The problem is that this will produce a mangled function name that cannot be demangled. In this case _Z4funcB3123v. GCC correctly rejects this: https://godbolt.org/z/vGjKMrEv4.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Nikolas Klauser (philnik777)

Currently clang accepts code like `[[gnu::abi_tag("123")]] void func() {}`. The problem is that this will produce a mangled function name that cannot be demangled. In this case `_Z4funcB3123v`. GCC correctly rejects this: https://godbolt.org/z/vGjKMrEv4.

[localspook]

I'd like to work on this.

[EugeneZelenko]

@localspook: Just create pull request and mention it on this page.

[localspook]

Opened #84272.