We currently don't support building Qt with GCC and -ansi (or -std=c++NN as opposed to -std=gnu++NN), because in that mode, the language still recognizes __int128_t, but the C++ standard library does not, leading to bloopers such as std::is_integral_v<__int128_t> == false or std::is_signed_v<__int128_t> == false, or simply std::numerical_limits<__int128_t> not being properly specialized. But we do have QT_NO_INT128, which, when defined, disabled all the Qt extended integer support. A user requested to allow compiling with -ansi again, to which I responded that they should define QT_NO_INT128 then, too, but of course, the sanity-check in qtypes.cpp ignored QT_NO_INT128 and would fire nonetheless, so this patch fixes that. [ChangeLog][QtCore] Made it possible to compile Qt with GCC in strict C++ mode (-ansi or -std=c++NN) again, provided QT_NO_INT128 is defined, too. Amends 30e04340dac26ebd09f9bc8ceb598e873ab63ba7. Pick-to: 6.10 6.9 6.8 Task-number: QTBUG-139280 Change-Id: I3e05d1f5e11b6a0a6a49fad53846f2b9cf0663a7 Reviewed-by: Ivan Solovev <ivan.solovev@qt.io> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>