https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67854
--- Comment #2 from Mikhail Maltsev <miyuki at gcc dot gnu.org> ---
(In reply to jos...@codesourcery.com from comment #1)
> I wonder if this is yet another issue with macros from system headers
> (bool being defined in a system header to expand to _Bool) ...
Looks like it is. In gimplify.c:gimplify_va_arg_expr we have:
/* Unfortunately, this is merely undefined, rather than a constraint
violation, so we cannot make this an error. If this call is never
executed, the program is still strictly conforming. */
warned = warning_at (loc, 0,
"%qT is promoted to %qT when passed through
%<...%>",
type, promoted_type);
And warning_at returns false. Also, for
#include <stdarg.h>
#define BOOL _Bool
void foo(va_list ap)
{
va_arg(ap, BOOL);
}
GCC outputs:
In file included from test2.c:1:0:
test2.c: In function 'foo':
test2.c:2:14: warning: '_Bool' is promoted to 'int' when passed through '...'
#define BOOL _Bool
^
test2.c:5:16: note: in expansion of macro 'BOOL'
va_arg(ap, BOOL);
^
test2.c:2:14: note: (so you should pass 'int' not '_Bool' to 'va_arg')
#define BOOL _Bool
^
test2.c:5:16: note: in expansion of macro 'BOOL'
va_arg(ap, BOOL);
^
test2.c:2:14: note: if this code is reached, the program will abort
#define BOOL _Bool
^
test2.c:5:16: note: in expansion of macro 'BOOL'
va_arg(ap, BOOL);
IMHO, it would be more correct to output something like this:
test2.c: In function 'foo':
test2.c:5:16: warning: '_Bool' is promoted to 'int' when passed through '...'
va_arg(ap, BOOL);
^
test2.c:2:14: note: expanded from macro 'BOOL'
#define BOOL _Bool
^
