On Thu, 5 Feb 2026, 23:58 Jakub Jelinek, <[email protected]> wrote: > On Wed, Feb 04, 2026 at 05:42:52PM -0500, Nathan Myers wrote: > > +#ifdef __cpp_concepts > > +template <typename _Kt, typename _Container> > > + concept __not_container_iterator = > > + (!is_convertible_v<_Kt&&, typename _Container::iterator> && > > + !is_convertible_v<_Kt&&, typename _Container::const_iterator>); > > + > > +template <typename _Kt, typename _Container> > > + concept __heterogeneous_key = > > + (!is_same_v<typename _Container::key_type, remove_cvref_t<_Kt>>) && > > Shouldn't this be __remove_cvref_t ? > I see > +FAIL: g++.dg/concepts/expression.C -std=gnu++17 (test for excess errors) > +UNRESOLVED: g++.dg/concepts/expression.C -std=gnu++17 compilation failed > to produce executable > remove_cvref_t is C++20 feature, and while concepts are also a C++20 > feature, we allow -fconcepts -std=c++17 to enable concepts already. >
Then maybe the new concepts should be guarded by __glibcxx_concepts for the library support, or by a macro specific to the container features. We don't need or want to find that concept for C++17. > Jakub > >
