https://gcc.gnu.org/g:925a744efec5a630eb9bf49e755c554a884fda99
commit r14-11446-g925a744efec5a630eb9bf49e755c554a884fda99
Author: Patrick Palka <ppa...@redhat.com>
Date: Thu Mar 13 09:15:21 2025 -0400
libstdc++: Fix ref_view branch of views::as_const [PR119135]
Unlike for span<X> and empty_view<X>, the range_reference_t of
ref_view<X> doesn't correspond to X. This patch fixes the ref_view
branch of views::as_const to correctly query its underlying range
type X.
PR libstdc++/119135
libstdc++-v3/ChangeLog:
* include/std/ranges: Include <utility>.
(views::__detail::__is_ref_view): Replace with ...
(views::__detail::__is_constable_ref_view): ... this.
(views::_AsConst::operator()): Replace bogus use of element_type
in the ref_view branch.
* testsuite/std/ranges/adaptors/as_const/1.cc (test03): Extend
test.
Reviewed-by: Tomasz Kamiński <tkami...@redhat.com>
Reviewed-by: Jonathan Wakely <jwak...@redhat.com>
(cherry picked from commit 50359c0a44381edb6dbd9359ef2ebdadbcc3ed42)
Diff:
---
libstdc++-v3/include/std/ranges | 12 ++++++------
libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc | 4 ++++
2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index a966699479bb..c2dcb0265660 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -46,6 +46,7 @@
#include <string_view>
#include <tuple>
#if __cplusplus > 202002L
+#include <utility>
#include <variant>
#endif
#include <bits/ranges_util.h>
@@ -9297,10 +9298,11 @@ namespace views::__adaptor
namespace __detail
{
template<typename _Tp>
- inline constexpr bool __is_ref_view = false;
+ inline constexpr bool __is_constable_ref_view = false;
template<typename _Range>
- inline constexpr bool __is_ref_view<ref_view<_Range>> = true;
+ inline constexpr bool __is_constable_ref_view<ref_view<_Range>>
+ = constant_range<const _Range>;
template<typename _Range>
concept __can_as_const_view = requires {
as_const_view(std::declval<_Range>()); };
@@ -9322,10 +9324,8 @@ namespace views::__adaptor
return views::empty<const element_type>;
else if constexpr (std::__detail::__is_span<_Tp>)
return span<const element_type,
_Tp::extent>(std::forward<_Range>(__r));
- else if constexpr (__detail::__is_ref_view<_Tp>
- && constant_range<const element_type>)
- return ref_view(static_cast<const element_type&>
- (std::forward<_Range>(__r).base()));
+ else if constexpr (__detail::__is_constable_ref_view<_Tp>)
+ return ref_view(std::as_const(std::forward<_Range>(__r).base()));
else if constexpr (is_lvalue_reference_v<_Range>
&& constant_range<const _Tp>
&& !view<_Tp>)
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
b/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
index c36786a8c5fa..3f1f8eb17726 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
@@ -63,6 +63,10 @@ test03()
std::vector<int> v;
std::same_as<ranges::ref_view<const std::vector<int>>>
auto r = views::as_const(v);
+
+ // PR libstdc++/119135
+ std::same_as<ranges::ref_view<const std::vector<int>>>
+ auto r2 = views::as_const(views::all(v));
}
int
