https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78235
--- Comment #2 from David Edelsohn <dje at gcc dot gnu.org> --- 20_util/variant/compile.cc produces a similar error: In file included from /nasfarm/edelsohn/src/src/libstdc++-v3/testsuite/20_util/variant/compile.cc:21: /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/variant: In instantiation of 'class std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >': /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/type_traits:881: required by substitution of 'template<class _Tp, class> static std::true_type std::__do_is_default_constructible_impl::__test(int) [with _Tp = std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >; <template-parameter-1-2> = <missing>]' /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/type_traits:892: required from 'struct std::__is_default_constructible_impl<std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >' /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/type_traits:143: required from 'struct std::__and_<std::__not_<std::is_void<std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, std::__is_default_constructible_impl<std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >' /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/type_traits:896: required from 'struct std::__is_default_constructible_atom<std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >' /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/type_traits:917: required from 'struct std::__is_default_constructible_safe<std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, false>' /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/type_traits:923: required from 'struct std::is_default_constructible<std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >' /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/type_traits:2966: required from 'constexpr const bool std::is_default_constructible_v<std::variant<int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >' /nasfarm/edelsohn/src/src/libstdc++-v3/testsuite/20_util/variant/compile.cc:56: required from here /tmp/GCC/powerpc-ibm-aix7.2.0.0/libstdc++-v3/include/variant:956: internal compiler error: tree check: expected field_decl, have template_decl in int_bit_position, at tree.h:5396
