https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114147
--- Comment #2 from __vic <victor.dyachenko at protonmail dot com> --- Shouldn't this be added? template<typename _Alloc, _ExplicitDefaultCtor<is_object<_Alloc>::value, _T1, _T2> = true> explicit _GLIBCXX20_CONSTEXPR tuple(allocator_arg_t __tag, const _Alloc& __a) : _Inherited(__tag, __a) { }