[Bug c/116302] transparent union does not work with {integral type, bitfield struct}

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116302

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
That is this is allowable:
```
unsigned long long f(unsigned long long v)
{
  return antiop(v).v;
}
```

But nothing else. That is even the return type is not transparent converable. 
Only arguments.