procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

libstdc++: Allow std::ranges::to to create unions

Browse source 
LWG 4229 points out that the std::ranges::to wording refers to class
types, but I added an assertion using std::is_class_v which only allows
non-union class types. LWG consensus is that unions should be allowed,
so this additionally uses std::is_union_v.

libstdc++-v3/ChangeLog:

	* include/std/ranges (ranges::to): Allow unions as well as
	non-union class types.
	* testsuite/std/ranges/conv/lwg4229.cc: New test.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
This commit is contained in:
Jonathan Wakely 2025-03-25 00:27:52 +00:00 • committed by Jonathan Wakely
parent e200f53a55
commit 479a0a8644
No known key found for this signature in database
2 changed files with 20 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
libstdc++-v3/include/std/ranges
View file

@ -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;

18
libstdc++-v3/testsuite/std/ranges/conv/lwg4229.cc Normal file
View file

@ -0,0 +1,18 @@
// { dg-do compile { target c++23 } }
// LWG 4229 std::ranges::to with union return type
#include <ranges>
union U
{
template<std::ranges::input_range R> U(std::from_range_t, R&&) { }
int i;
};
void
test_lwg4229(std::ranges::subrange<int*> r)
{
U u = std::ranges::to<U>(r);
}