Problem when declaring enum constant with old style function parameter declaration in C11.

[ebdd6ebc-1612-4e9b-aee1-f7d2b6361d5f]

Bugzilla Link	39929
Version	trunk
OS	All
CC	@zygoloid

Extended Description

Consider the following C11 program (prog.c):

void f(e) enum { x } e; { x; }

int main() { }

I was compiling this program with:

clang prog.c -std=c11 -pedantic-errors "-w"

The expected behaviour is that it should work, but I get the following error:

error: use of undeclared identifier 'x'

Note that it works fine when using the new style of declaring function parameters.

Also note that it works fine in gcc.

Link to online compiler:

https://wandbox.org/permlink/CGczhD2xFRJkUzTs

[llvmbot]

@llvm/issue-subscribers-c

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[AaronBallman]

Issue reproduces as of Clang 16.0.0: https://gcc.godbolt.org/z/f6jEGeaaz