[Bug c++/89898] invalid function template definition with non-type class argument accepted

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89898

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is valid C++ 20 too:
struct A { int t; };
template <A a> struct X { int d = a.t; };
template<X<A{}> a > int f () { return a.d; }  


int g(void)
{
  return f<X<A{0}>{1}>();
}

Yes I know it looks off but it is valid now and f<<X<A{0}>{1}> will return 1.
Note {} and {0} are the same here really.


Even something like this is valid now too:
struct A { int t; };
template <A a> struct X { int d = a.t; };
template<A a, X<a> x > int f () { return x.d; }  


int g(void)
{
  return f<A{2}, X<A{2}>{1}>();
}