https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79452
--- Comment #9 from Eric Fiselier <eric at efcs dot ca> --- I think it would be nice to be able to dispatch differently depending on being called at compile time or runtime. However the ability to dispatch on that condition doesn't have to be usable in "if constexpr". That way we don't run into any instantiation problems. If that behavior is desireable enough I think it could be simply implemented as an invented __ctfe__ function local variable that changes value.