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* [gcc r12-4587] libstdc++: Implement LWG 3481 change to ranges::viewable_range
@ 2021-10-21 1:38 Patrick Palka
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From: Patrick Palka @ 2021-10-21 1:38 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:a2c2dcc6ca205a8c5c76b04ef2eb4fb097dcb069
commit r12-4587-ga2c2dcc6ca205a8c5c76b04ef2eb4fb097dcb069
Author: Patrick Palka <ppalka@redhat.com>
Date: Wed Oct 20 21:34:18 2021 -0400
libstdc++: Implement LWG 3481 change to ranges::viewable_range
libstdc++-v3/ChangeLog:
* include/bits/ranges_base.h (viewable_range): Adjust as per
LWG 3481.
* testsuite/std/ranges/adaptors/all.cc (test07): New test.
Diff:
---
libstdc++-v3/include/bits/ranges_base.h | 3 ++-
libstdc++-v3/testsuite/std/ranges/adaptors/all.cc | 15 +++++++++++++++
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h
index 7801b2fd023..43b0b9f7bf3 100644
--- a/libstdc++-v3/include/bits/ranges_base.h
+++ b/libstdc++-v3/include/bits/ranges_base.h
@@ -688,7 +688,8 @@ namespace ranges
/// A range which can be safely converted to a view.
template<typename _Tp>
concept viewable_range = range<_Tp>
- && (borrowed_range<_Tp> || view<remove_cvref_t<_Tp>>);
+ && ((view<remove_cvref_t<_Tp>> && constructible_from<remove_cvref_t<_Tp>, _Tp>)
+ || (!view<remove_cvref_t<_Tp>> && borrowed_range<_Tp>));
// [range.iter.ops] range iterator operations
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc
index 9a6a31e6cb4..ce1384c2890 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc
@@ -159,6 +159,20 @@ test06()
static_assert(!noexcept(views::all(BorrowedRange<false, false>(x))));
}
+void
+test07()
+{
+ // LWG 3481
+ struct view_t : ranges::empty_view<int> { // move-only view
+ view_t(const view_t&) = delete;
+ view_t(view_t&&) = default;
+ view_t& operator=(const view_t&) = delete;
+ view_t& operator=(view_t&&) = default;
+ };
+ static_assert(std::movable<view_t> && !std::copyable<view_t>);
+ static_assert(!ranges::viewable_range<view_t&>);
+}
+
int
main()
{
@@ -168,4 +182,5 @@ main()
static_assert(test04());
test05();
test06();
+ test07();
}
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