https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110031
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Self-contained testcase without any headers:
```
template <typename T>
[[deprecated]]
inline constexpr bool t = true ;
template <bool a>
struct enableif;
template<>
struct enableif<true>
{
using y = int;
};
template <bool a>
using enableif_t = enableif<a>::y;
template <typename T, enableif_t<t<T>> = 0>
struct A { A(T &&) { }};
template <typename T>
struct A<T> {
A(T &&) = delete;
};
int main(void)
{
A<double> a{5.3};
return 0;
}
```
