From 5a41ab8da087617d785f563b76f5c2fd6600b4c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arsen=20Arsenovi=C4=87?= <arsen@aarsen.me>
Date: Tue, 24 Dec 2024 12:29:02 +0100
Subject: [PATCH] libstdc++: don't implicit-construct _Yielded_decvref
[PR118022]
This overload requires
constructible_from<remove_cvref_t<yielded>,
const remove_reference_t<yielded>&>
... but then tries to construct remove_cvref_t<yielded> implicitly,
which means it imposes an additional constraint not in the standard.
libstdc++-v3/ChangeLog:
PR libstdc++/118022
* include/std/generator
(_Promise_erased::yield_value(const _Yielded_deref&)): Don't
implicit-constuct _Yielded_decvref.
* testsuite/24_iterators/range_generators/pr118022.cc: New test.
---
libstdc++-v3/include/std/generator | 2 +-
.../24_iterators/range_generators/pr118022.cc | 16 ++++++++++++++++
2 files changed, 17 insertions(+), 1 deletion(-)
create mode 100644 libstdc++-v3/testsuite/24_iterators/range_generators/pr118022.cc
diff --git a/libstdc++-v3/include/std/generator b/libstdc++-v3/include/std/generator
index bba85bd0aa4e..3a19d535ef86 100644
--- a/libstdc++-v3/include/std/generator
+++ b/libstdc++-v3/include/std/generator
@@ -144,7 +144,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
requires (is_rvalue_reference_v<_Yielded>
&& constructible_from<_Yielded_decvref,
const _Yielded_deref&>)
- { return _Copy_awaiter(__val, _M_bottom_value()); }
+ { return _Copy_awaiter(_Yielded_decvref(__val), _M_bottom_value()); }
template<typename _R2, typename _V2, typename _A2, typename _U2>
requires std::same_as<_Yield2_t<_R2, _V2>, _Yielded>
diff --git a/libstdc++-v3/testsuite/24_iterators/range_generators/pr118022.cc b/libstdc++-v3/testsuite/24_iterators/range_generators/pr118022.cc
new file mode 100644
index 000000000000..d8915bb38dc4
--- /dev/null
+++ b/libstdc++-v3/testsuite/24_iterators/range_generators/pr118022.cc
@@ -0,0 +1,16 @@
+// { dg-do compile { target c++23 } }
+#include <generator>
+
+struct O {
+ O() = default;
+ explicit O(const O&) = default;
+};
+
+std::generator<O&&> gen() {
+ const O o;
+ co_yield o;
+}
+
+int
+main()
+{}
--
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