[Bug c++/127627] New: What's the right overload resolution for ``public: X(const X&); private: explicit X(const X&) requires T::value = default;``?

[songb432 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127627

            Bug ID: 127627
           Summary: What's the right overload resolution for ``public:
                    X(const X&); private: explicit X(const X&) requires
                    T::value = default;``?
           Product: gcc
           Version: 16.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: songb432 at gmail dot com
  Target Milestone: ---

https://godbolt.org/z/GEW6Y3376

template <class T>
struct X
{
  X() = default;
  X(const X&) { throw; }
private:
  explicit X(const X&) requires (T::value) = default;
};

struct S { static constexpr bool value = true; };

int main()
{
    const X<S> x;
    X<S> x2 = x;
}


Clang compiles. GCC doesn't. Who's on the right side? I guess it's Clang,
because the two copy constructor is simply `ignored` in GCC. Is it a bug,
seriously?