missing_const_for_fn triggers for C-unwind

[matthiaskrgr]

Summary

#[no_mangle]
const extern "C-unwind" fn unwind() {
// clippy suggests:
//  const extern "C-unwind" fn unwind() {
// but this requires the #![feature(const_extern_fn)] gate
    panic!();
}

fn main() {
    extern "C" {
        fn unwind();
    }
    unsafe { unwind() }
}

Lint Name

No response

Reproducer

I tried this code:

<code>

I saw this happen:

<output>

I expected to see this happen:

Version

rustc 1.81.0-nightly (9c3bc805d 2024-06-27)
binary: rustc
commit-hash: 9c3bc805dd9cb84019c124b9a50fdff1e62a7ec9
commit-date: 2024-06-27
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7

Additional Labels

No response

[J-ZhengLi]

@rustbot claim