[Bug c++/77598] constexpr compilation failure on reference type casting

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77598

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |jason at gcc dot gnu.org,
                   |                            |redi at gcc dot gnu.org
            Summary|consexpr compilation        |constexpr compilation
                   |failure on reference type   |failure on reference type
                   |casting                     |casting

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
This error has been added for DR1188 resolution.

Slightly reduced testcase:
template <typename T>
struct A { static constexpr T a = T (); };
template <typename T>
constexpr T A<T>::a;
struct B
{
  int b;
  constexpr int foo () const { return b; }
  constexpr B (const int &x) : b(x) {};
};
struct C : public B
{
  constexpr C () : B(50) {};
};
struct D : public C
{
};
struct E
{
  static constexpr const auto &e = A<D>::a;
};
constexpr const B &f = E::e;
constexpr const int g = f.foo ();