[Bug c++/110580] [14 Regression] gcc fails to typecheck nix-2.16.1 source: error: invalid initialization of reference of type

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110580

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
yes my theory is correct and becomes obvious with the error message for:
```

struct s0 {};
struct s1 {};
struct s2 {};
template <typename T>
struct t;
template <typename _Key> 
struct s3 {
  template <typename _Up, typename _Vp = _Up>
  static constexpr bool __usable_key = t<_Vp>::v;
  static_assert(__usable_key<s0>);
  static_assert(__usable_key<s1>);
};
s3<s2> t2;
```
Error message:
```
<source>: In instantiation of 'constexpr const bool s3<s2>::__usable_key<s0,
s2>':
...
<source>: In instantiation of 'constexpr const bool s3<s2>::__usable_key<s1,
s2>':
```
s2 there is definitely incorrect