[Bug c++/122269] Error on constexpr structured binding using tuple protocol

[tkaminsk at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122269

--- Comment #6 from Tomasz Kamiński <tkaminsk at gcc dot gnu.org> ---
I have now realized that following also does not work without symbolic address,
so I indeed need P2686R4.
  constexpr auto e = _IndexPack<N>();
  constexpr std::tuple_element_t<0, _IndexPack<N>>&& e1 = e.template get<0>();

I think this can be closed as duplicate of PR117784.