[Bug target/18742] small struct not passed correctly as vararg

["chli002 at rz dot uni-saarland dot de" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From chli002 at rz dot uni-saarland dot de  2005-01-10 15:32 -------
I have found similar cases; it appears that the crucial part is a {short;char} struct or union which is 
passed as a var arg. Here is a similar program, somewhat smaller and with easier to understand names. 
Again, on MacOS X 10.3 with gcc version 3.3 20030304:

$ ./foo 
foo.c:17: failed assertion `y.f == i.f'
Abort trap

#include <stdarg.h>
#include <assert.h>
union  A { float a; double b; } c         = { 52.54 };
struct B { double d; unsigned int e; } h  = { 78.01, 834U };
union  C { short int f; char g; } i       = { 68 };
struct D { char j; double k; } n          = { 'c', 31.01 };
struct E { long long int l; double m; } o = { 167L, 17.2 };

union  A callee( struct D a, struct E b, ... )
{
    va_list ap;
    struct B x;
    union  C y;
    va_start (ap, b);
    x = va_arg (ap, struct B);
    y = va_arg (ap, union C);
    assert (y.f ==  i.f);
    va_end (ap);
    return c;
}
int main( int argc, char **arg ) { 
    union A r;
    r = callee (n, o, h, i);
    assert (c.a ==  r.a);
    return 0;
}




-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18742