[Bug c++/94922] Functional cast from base class to derived class incorrectly accepted with -std=c++2a

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94922

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Another testcase that exhibits the 10/11 regression:

struct base {};
struct derived : base {};

void
foo()
{
  derived a = derived(base());
}