[Bug c++/104111] [DR2589] Concept evaluation depends on context where it was first checked

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104111

--- Comment #11 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Along the lines of comment #3, here's another example that would "misbehave" if
we were to make concept-id evaluation context-independent:

  template<class T> requires C<T> || D<T>
  void f() {
    if constexpr (C<T>) // potentially IFNDR if evaluation of C<T>
                        // depends on access context of f (though
                        // in practice we'll just reuse the cached
                        // value obtained earlier during satisfaction
                        // with the right access context)
      ...
    else
      ...
  }