https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65808
Bug ID: 65808
Summary: -pedantic -std=gnu11 results in warning for
transparent_union usage
Product: gcc
Version: 4.9.2
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: equinox-gccbugs at diac24 dot net
Created attachment 35359
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35359&action=edit
test program, compile with -std=gnu11 -pedantic
Trying to use a transparent_union results in a warning when -pedantic is used,
even though -std=gnu11 is specified.
Test program is this:
(gcc -std=gnu11 -pedantic -c /tmp/uniontest.c)
struct a { int a; };
struct b { int b; };
__extension__ union ab {
struct a *pa;
struct b *pb;
} __attribute__ ((transparent_union));
extern void func1 (union ab arg);
__extension__ extern void func2 (union ab arg);
void test(void)
{
struct a sa = { 1 };
func1(&sa); /* warning */
__extension__ func1(&sa); /* no warning */
func2(&sa); /* warning */
}
Expected behaviour: no warning at all, or some way to put __extension__ on the
union or the function prototype.
Actual behaviour: __extension__ must be used on each and every individual
function call, or a warning occurs:
/tmp/uniontest.c: In function ‘test’:
/tmp/uniontest.c:15:2: warning: ISO C prohibits argument conversion to union
type [-Wpedantic]
func1(&sa); /* warning */
^
/tmp/uniontest.c:17:2: warning: ISO C prohibits argument conversion to union
type [-Wpedantic]
func2(&sa); /* warning */
^
