https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121951
--- Comment #1 from Alejandro Colomar <foss+...@alejandro-colomar.es> ---
With gcc built from source, the diagnostic texts change, but the situation is
the same:
alx@debian:~/tmp$ /opt/local/gnu/gcc/countof22/bin/gcc void_fwd.c
void_fwd.c:3:14: error: ‘void’ must be the only parameter and unnamed
3 | void f(void; void);
| ^~~~
void_fwd.c:3:8: error: parameter ‘({anonymous})’ has just a forward declaration
3 | void f(void; void);
| ^~~~
void_fwd.c:4:12: error: expected declaration specifiers or ‘...’ before ‘;’
token
4 | void f( ; void);
| ^
void_fwd.c:5:12: error: expected declaration specifiers or ‘...’ before ‘;’
token
5 | void f( ; );
| ^
