https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125605
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to songb432 from comment #6)
> I suppose you're right there. But let's see `Example3`:
> ```
> namespace Example3 { // see also
> https://eel.is/c++draft/temp.constr#decl-example-2
> template <class T> concept C = true;
> template <class T> struct A {
> template <class U> U f(U) requires C<typename T::type>; // #1
> template <class U> U f(U) requires C<T>; // #2
> };
> using U = decltype(A<int>{}.f(2));
> } // namespace Example3
> ```
> It doesn't compile because the compiler thinks `call of overloaded 'f(int)'
> is ambiguous`.
This looks like exactly the same issue, your concept C doesn't use T at all.
(In reply to songb432 from comment #7)
> There's another issue: GCC 10 ~ 16 all behaves the same on those examples,
> but Clang 17 ~ 21 behaves (the way I expect) different from GCC, but but,
> Clang 22 behaves the same with GCC. I'm not sure if Clang 22 did think the
> behaviour of Clang 17 ~ 21 has any bug, since I didn't find anything
> concerning this.
> See that on https://godbolt.org/z/zdosxqdf1
So Clang fixed a bug ... that's good, isn't it?
