Tested x86_64-linux, pushed to trunk.
In C++17 mode all callers of _S_relocate have already done: if constexpr (_S_use_relocate()) so we don't need to repeat that check and use tag dispatching to avoid ill-formed instantiations. libstdc++-v3/ChangeLog: * include/bits/stl_vector.h (vector::_S_do_relocate): Remove C++20 constexpr specifier. (vector::_S_relocate) [__cpp_if_constexpr]: Call __relocate_a directly without tag dispatching. --- libstdc++-v3/include/bits/stl_vector.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h index 4587757637e..36b2cff3d78 100644 --- a/libstdc++-v3/include/bits/stl_vector.h +++ b/libstdc++-v3/include/bits/stl_vector.h @@ -481,14 +481,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER return _S_nothrow_relocate(__is_move_insertable<_Tp_alloc_type>{}); } - static _GLIBCXX20_CONSTEXPR pointer + static pointer _S_do_relocate(pointer __first, pointer __last, pointer __result, _Tp_alloc_type& __alloc, true_type) noexcept { return std::__relocate_a(__first, __last, __result, __alloc); } - static _GLIBCXX20_CONSTEXPR pointer + static pointer _S_do_relocate(pointer, pointer, pointer __result, _Tp_alloc_type&, false_type) noexcept { return __result; } @@ -497,8 +497,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER _S_relocate(pointer __first, pointer __last, pointer __result, _Tp_alloc_type& __alloc) noexcept { +#if __cpp_if_constexpr + // All callers have already checked _S_use_relocate() so just do it. + return std::__relocate_a(__first, __last, __result, __alloc); +#else using __do_it = __bool_constant<_S_use_relocate()>; return _S_do_relocate(__first, __last, __result, __alloc, __do_it{}); +#endif } #endif // C++11 -- 2.31.1