modernc.org/cc@v1.0.1/testdata/gcc-6.3.0/gcc/testsuite/gcc.c-torture/execute/pr29006.c (about)

     1  struct __attribute__((__packed__)) s { char c; unsigned long long x; };
     2  void __attribute__((__noinline__)) foo (struct s *s) { s->x = 0; }
     3  int main (void) { struct s s = { 1, ~0ULL }; foo (&s); return s.x != 0; }