https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125605
--- Comment #10 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to songb432 from comment #9)
> I agree. So it's all about parameter mapping. I misunderstood some rule
> about normalization. But I still can't figure out this:
> ```
> 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
> };
> template <> template <class U>
> U A<int>::f(U u) requires C<int> { return u; } // OK,
> specializes #2
> ```
> This does compile, while `A<int>{}.f(2)` does not. Why? Is it a DR?
Declaration matching considers the written form of a constraint-expression.
Constraint satisfaction (and subsumption) considers the normalized form.
