[gcc r10-9915] libstdc++: Fix constraint on std::optional assignment [PR 100982]
Jonathan Wakely
redi@gcc.gnu.org
Mon Jun 14 18:52:09 GMT 2021
https://gcc.gnu.org/g:37864c5e6aa6befc17051f162c02d4f593a57e57
commit r10-9915-g37864c5e6aa6befc17051f162c02d4f593a57e57
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Wed Jun 9 11:03:15 2021 +0100
libstdc++: Fix constraint on std::optional assignment [PR 100982]
libstdc++-v3/ChangeLog:
PR libstdc++/100982
* include/std/optional (optional::operator=(const optional<U>&)):
Fix value category used in is_assignable check.
* testsuite/20_util/optional/assignment/100982.cc: New test.
(cherry picked from commit b3fce1bd45f72cc9e55fb7431762e92e30fefcf1)
Diff:
---
libstdc++-v3/include/std/optional | 2 +-
.../testsuite/20_util/optional/assignment/100982.cc | 17 +++++++++++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/std/optional b/libstdc++-v3/include/std/optional
index d473b5369be..e3fbe625f25 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -798,7 +798,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Up>
enable_if_t<__and_v<__not_<is_same<_Tp, _Up>>,
is_constructible<_Tp, const _Up&>,
- is_assignable<_Tp&, _Up>,
+ is_assignable<_Tp&, const _Up&>,
__not_<__converts_from_optional<_Tp, _Up>>,
__not_<__assigns_from_optional<_Tp, _Up>>>,
optional&>
diff --git a/libstdc++-v3/testsuite/20_util/optional/assignment/100982.cc b/libstdc++-v3/testsuite/20_util/optional/assignment/100982.cc
new file mode 100644
index 00000000000..ae565250d68
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/optional/assignment/100982.cc
@@ -0,0 +1,17 @@
+// { dg-do compile { target c++17 } }
+
+#include <optional>
+
+struct U {};
+
+struct T {
+ explicit T(const U&);
+ T& operator=(const U&);
+ T& operator=(U&&) = delete;
+};
+
+int main() {
+ std::optional<U> opt1;
+ std::optional<T> opt2;
+ opt2 = opt1; // PR libstdc++/100982
+}
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