[Bug c++/115814] New: class template argument deduction failed in C++20

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115814

            Bug ID: 115814
           Summary: class template argument deduction failed in C++20
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

template<class... Ts>
struct overloaded : Ts... { };
// explicit deduction guide (not needed as of C++20)
// template<class... Ts>
// overloaded(Ts...) -> overloaded<Ts...>;

int main() {
  auto s = overloaded([]{}, []{});
}

GCC rejects this, and changes (...) to {...} can work, but I think the above
should be well-formed.

https://godbolt.org/z/xah5fr8rn