[Bug c++/110938] miscompile if implicit special member is deleted and mutable

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110938

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|miscompile if implicit      |miscompile if implicit
                   |special member is deleted   |special member is deleted
                   |in a subtle way             |and mutable

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced:
```
struct X {
  X(X &) = delete;
  X(X&&) = delete;
  X(const X&) = default;
};

struct Y {
#if 1
  mutable
#endif
   X x;
  int n;
};

void print(int);

Y f();

void g() {
  print(f().n);
}
```

If we change `#if 1` to `#if 0` then GCC does the correct thing.