https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124888
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- Jason suggested that the problem is that std::type_info isn't visible to name lookup, so g++ gives the "must ‘#include <typeinfo>’ before using ‘typeid’" error. But std::type_info is reachable because it's been imported, so g++ needs to check that too.
