[Bug c++/123413] ICE: in gimplify_var_or_parm_decl, at gimplify.cc with statement expression inside a template and decltype(auto)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123413

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced:
```
template <class T=int>
void G() {
  int x = 42;
  decltype(auto) y = ({ int z = x; z; });
}

int main() {
    G();
}
```