[Bug c++/88337] Implement P1002R1, P1327R1, P1330R0, C++20 relaxations of constexpr restrictions.

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88337

--- Comment #9 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Not entirely true, this template case should be accepted:

#include <typeinfo>

struct B { virtual void f(); };
struct B2 : B { };

template<typename T>
constexpr bool
fn ()
{
  constexpr B2 b2;
  static_assert(&typeid(b2) == &typeid(B2));
  return true;
}

static_assert (fn<int>());