[Bug c++/127255] ICE on contracts and aliased source_location

[ivan.lazaric.gcc at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127255

--- Comment #1 from Ivan Lazaric <ivan.lazaric.gcc at gmail dot com> ---
Similarly ices on union:
```cpp
namespace std {
    union source_location {};
}

void foo() pre(true) {}
```