[Bug c/126264] attribute error is ignored with invalid param

[jg at jguk dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126264

--- Comment #3 from Jonny Grant <jg at jguk dot org> ---
Would be good to emit an error diagnostic on this as well? clang emits an error

https://godbolt.org/z/T6cqKehq7

#include <stddef.h>

const char * const message = "hello";
void _fail() __attribute__ ((error(message)));

int main()
{
    _fail();
}