https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92847
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Reduced:
template<typename T>
struct A {
A() {}
template<typename U>
A(const A<U>&) {}
bool operator==(const A&) const { return true; }
};
A<const int> a;
A<int> b;
auto c = (a == b);
Compiled with -std=gnu++2a:
cmp.cc:13:13: error: ambiguous overload for 'operator==' (operand types are
'A<const int>' and 'A<int>')
13 | auto c = (a == b);
| ~ ^~ ~
| | |
| | A<int>
| A<const int>
cmp.cc:8:8: note: candidate: 'bool A<T>::operator==(const A<T>&) const [with T
= int]' (reversed)
8 | bool operator==(const A&) const { return true; }
| ^~~~~~~~
cmp.cc:8:8: note: candidate: 'bool A<T>::operator==(const A<T>&) const [with T
= const int]'
