Found by:
find -name '*.h' |xargs grep -i 'attribute.*(([a-z]'
For an example of the type of bugs this causes, try compiling this valid
C11 program (it's valid because 'noreturn' is reserved for use in the
user namespace unless you include <stdnoreturn.h>):
$ cat foo.c
#define noreturn __attribute__((noreturn))
#include <stdlib.h>
$ gcc -c -o foo.o -Wall foo.c
In file included from /usr/include/stdlib.h:11:0,
from foo.c:2:
foo.c:1:18: error: expected ')' before '__attribute__'
#define noreturn __attribute__((noreturn))
^
/usr/include/stdlib.h:66:28: error: expected ',' or ';' before ')' token
_VOID _EXFUN(abort,(_VOID) _ATTRIBUTE ((noreturn)));
^