On Fri, Feb 6, 2026 at 10:14 AM Nathan Myers <[email protected]> wrote:
> The commit 3f7905550483408a2c4c5096a1adc8d7e863eb12 defined a > concept __heterogeneous_key using a name not defined in C++17. > This is fixed by guarding the definition behind a name defined > in C++23 the earliest Standard that uses the definition. > > https://gcc.gnu.org/pipermail/gcc-patches/2026-February/707814.html > > libstdc++-v3/ChangeLog > * include/bits/stl_function.h (concept __heterogeneous_key): > Guard with __glibcxx_associative_heterogeneous_erasure > --- > LGTM, defining the concept only if we provide extensions that need them is reasonable. We can always change that if more places will depend on that and conditions will become unwieldy. I think you can commit that as an obvious fix, without need for Jonathan approval. libstdc++-v3/include/bits/stl_function.h | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/libstdc++-v3/include/bits/stl_function.h > b/libstdc++-v3/include/bits/stl_function.h > index 657f40bca2e..1312564216b 100644 > --- a/libstdc++-v3/include/bits/stl_function.h > +++ b/libstdc++-v3/include/bits/stl_function.h > The file does not include bits/version.h, so we assume that it is included before, and we already use __glibcxx_transparent_operators in the file, so this is not a problem of this change. I have looked, and we bring bits version via type_traits inclusion. > @@ -1525,7 +1525,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > #endif > #endif > > -#ifdef __cpp_concepts > +#ifdef __glibcxx_associative_heterogeneous_erasure // C++23 > template <typename _Kt, typename _Container> > concept __not_container_iterator = > (!is_convertible_v<_Kt&&, typename _Container::iterator> && > @@ -1533,8 +1533,7 @@ template <typename _Kt, typename _Container> > > template <typename _Kt, typename _Container> > concept __heterogeneous_key = > - (!is_same_v<typename _Container::key_type, > - typename remove_cvref<_Kt>::type>) && > + (!is_same_v<typename _Container::key_type, remove_cvref_t<_Kt>>) && > __not_container_iterator<_Kt, _Container>; > #endif > > -- > 2.52.0 > >
