This is LWG 3220 which is about to become Tentatively Ready.
libstdc++-v3/ChangeLog:
* include/std/atomic (__atomic_val_t): Use __type_identity_t
instead of atomic<T>::value_type, as per LWG 3220.
* testsuite/29_atomics/atomic/lwg3220.cc: New test.
(cherry picked from commit
30cc1b65e4efa1a2c57fec5574fcae7a446b822f)
atomic_flag_clear(volatile atomic_flag* __a) noexcept
{ atomic_flag_clear_explicit(__a, memory_order_seq_cst); }
-
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 3220. P0558 broke conforming C++14 uses of atomic shared_ptr
template<typename _Tp>
- using __atomic_val_t = typename atomic<_Tp>::value_type;
+ using __atomic_val_t = __type_identity_t<_Tp>;
template<typename _Tp>
using __atomic_diff_t = typename atomic<_Tp>::difference_type;
--- /dev/null
+// { dg-do compile { target c++11 } }
+// DR 3220. P0558 broke conforming C++14 uses of atomic shared_ptr
+
+#include <atomic>
+#include <memory>
+
+struct Abstract { virtual void test() = 0; };
+struct Concrete : Abstract { virtual void test() override {} };
+
+int main() {
+ std::shared_ptr<Abstract> ptr;
+ std::atomic_store<Abstract>(&ptr, std::make_shared<Concrete>());
+}