[Bug c++/114395] [c++20+] std::is_constructible_v result of const reference incorrect

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114395

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Except this works with C++20+ for GCC:
```
struct A {
    int a;
};
struct B : public A {};

void f(const A &a)
{
        typedef const B & Btype;
        Btype b(a);
}

```