https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79433
--- Comment #14 from Marc Mutz <marc.mutz at kdab dot com> --- You can hide behind the letter of the standard, but you cannot escape the simple fact that __has_include is the intended mechanism to check for library features that added a new header. Proof: You need to include that header to get at the __cpp_lib macro, if any. If you can't use __has_include for that, because the header stabs you in the back, then that intended mechanism is broken. Call it conforming if you want, but it simply isn't.
