diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index 34c6f113e21..7a339c51368 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -9421,7 +9421,7 @@ namespace __detail to [[nodiscard]] (_Rg&& __r, _Args&&... __args) { static_assert(!is_const_v<_Cont> && !is_volatile_v<_Cont>); - static_assert(is_class_v<_Cont>); + static_assert(is_class_v<_Cont> || is_union_v<_Cont>); if constexpr (__detail::__toable<_Cont, _Rg>) { @@ -9580,7 +9580,7 @@ namespace __detail to [[nodiscard]] (_Args&&... __args) { static_assert(!is_const_v<_Cont> && !is_volatile_v<_Cont>); - static_assert(is_class_v<_Cont>); + static_assert(is_class_v<_Cont> || is_union_v<_Cont>); using __detail::_To; using views::__adaptor::_Partial; diff --git a/libstdc++-v3/testsuite/std/ranges/conv/lwg4229.cc b/libstdc++-v3/testsuite/std/ranges/conv/lwg4229.cc new file mode 100644 index 00000000000..780ed1fd932 --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/conv/lwg4229.cc @@ -0,0 +1,18 @@ +// { dg-do compile { target c++23 } } + +// LWG 4229 std::ranges::to with union return type + +#include + +union U +{ + template U(std::from_range_t, R&&) { } + + int i; +}; + +void +test_lwg4229(std::ranges::subrange r) +{ + U u = std::ranges::to(r); +}