https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94753
--- Comment #3 from r_new at rambler dot ru --- Don't know gcc code, but /* For C++11+ __cpp_constexpr and __cpp_static_assert should be defined. */ #if __cplusplus >= 201103L is not true. All standard predefined macros listed in chapter "16.8 Predefined macro names" C++11 standard. But for C++20 it's true.