https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67854
Bug ID: 67854
Summary: Missing diagnostic for passing bool to va_arg
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: miyuki at gcc dot gnu.org
Target Milestone: ---
Consider the following code:
$ cat test.c
#include <stdarg.h>
void foo(va_list ap)
{
va_arg(ap, char);
va_arg(ap, unsigned char);
}
$ cc1 -std=c99 test.c
In file included from test.c:1:0:
test.c: In function 'foo':
test.c:5:16: warning: 'char' is promoted to 'int' when passed through '...'
va_arg(ap, char);
^
test.c:5:16: note: (so you should pass 'int' not 'char' to 'va_arg')
test.c:5:16: note: if this code is reached, the program will abort
test.c:6:16: warning: 'unsigned char' is promoted to 'int' when passed through
'...'
va_arg(ap, unsigned char);
^
test.c:6:16: note: if this code is reached, the program will abort
However:
$ cat test2.c
#include <stdbool.h>
#include <stdarg.h>
void foo(va_list ap)
{
va_arg(ap, bool);
}
$ cc1 -std=c99 -Wall -Wextra test2.c
va_arg(ap, bool) is expanded into __builtin_trap, but no warning is issued.
