libstdc++: Fix for explicit copy ctors in <thread> and <future> [PR106695]

When I changed std::thread and std::async to avoid unnecessary move
construction of temporaries, I introduced a regression where types with
an explicit copy constructor could not be passed to std::thread or
std::async. The fix is to add a constructor instead of using aggregate
initialization of an unnamed temporary.

libstdc++-v3/ChangeLog:

	PR libstdc++/106695
	* include/bits/std_thread.h (thread::_State_impl): Forward
	individual arguments to _Invoker constructor.
	(thread::_Invoker): Add constructor. Delete copies.
	* include/std/future (__future_base::_Deferred_state): Forward
	individual arguments to _Invoker constructor.
	(__future_base::_Async_state_impl): Likewise.
	* testsuite/30_threads/async/106695.cc: New test.
	* testsuite/30_threads/thread/106695.cc: New test.

(cherry picked from commit 5abe0657553580bd1b7488dd84d55138a8d9f23c)

diff --git a/libstdc++-v3/include/bits/std_thread.h b/libstdc++-v3/include/bits/std_thread.h
index dd625de3bc3ed31cfef3c42692c13d1c3ec74232..6adf5e6b467ae9ddc4ffc260c4367f5326744248 100644 (file)
--- a/libstdc++-v3/include/bits/std_thread.h
+++ b/libstdc++-v3/include/bits/std_thread.h
@@ -203,7 +203,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
        template<typename... _Args>
          _State_impl(_Args&&... __args)
-         : _M_func{{std::forward<_Args>(__args)...}}
+         : _M_func(std::forward<_Args>(__args)...)
          { }
 
        void
@@ -237,6 +237,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     template<typename _Tuple>
       struct _Invoker
       {
+       template<typename... _Args>
+         explicit
+         _Invoker(_Args&&... __args)
+         : _M_t(std::forward<_Args>(__args)...)
+         { }
+
        _Tuple _M_t;
 
        template<typename>

diff --git a/libstdc++-v3/include/std/future b/libstdc++-v3/include/std/future
index 3bdbc636f691dd43cd9ba14f7cb2ed725f91d7bf..6cda28c84cf78cbe14e7b8b75ff3425bd7c6cdcb 100644 (file)
--- a/libstdc++-v3/include/std/future
+++ b/libstdc++-v3/include/std/future
@@ -1659,7 +1659,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        explicit
        _Deferred_state(_Args&&... __args)
        : _M_result(new _Result<_Res>()),
-         _M_fn{{std::forward<_Args>(__args)...}}
+         _M_fn(std::forward<_Args>(__args)...)
        { }
 
     private:
@@ -1726,7 +1726,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        explicit
        _Async_state_impl(_Args&&... __args)
        : _M_result(new _Result<_Res>()),
-         _M_fn{{std::forward<_Args>(__args)...}}
+         _M_fn(std::forward<_Args>(__args)...)
        {
          _M_thread = std::thread{&_Async_state_impl::_M_run, this};
        }

diff --git a/libstdc++-v3/testsuite/30_threads/async/106695.cc b/libstdc++-v3/testsuite/30_threads/async/106695.cc
new file mode 100644 (file)
index 0000000..7499634
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/async/106695.cc
@@ -0,0 +1,29 @@
+// { dg-do compile { target c++11 } }
+// { dg-require-gthreads "" }
+
+// PR libstdc++/106695
+// Explicit copy constructor does not work for a parameter passed via std::async
+
+#include <future>
+
+struct A {
+  A() = default;
+  explicit A(const A&) = default;
+};
+
+void func(const A&) { }
+
+void
+test_async()
+{
+  (void) std::async(std::launch::async, func, A{});
+  (void) std::async(std::launch::deferred, func, A{});
+  (void) std::async(func, A{});
+}
+
+void
+test_task()
+{
+  std::packaged_task<void(const A&)> task(func);
+  task(A{});
+}

diff --git a/libstdc++-v3/testsuite/30_threads/thread/106695.cc b/libstdc++-v3/testsuite/30_threads/thread/106695.cc
new file mode 100644 (file)
index 0000000..97e9e92
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/thread/106695.cc
@@ -0,0 +1,21 @@
+// { dg-do compile { target c++11 } }
+// { dg-require-gthreads "" }
+
+// PR libstdc++/106695
+// Explicit copy constructor does not work for a parameter passed via std::async
+
+#include <thread>
+
+struct A {
+  A() = default;
+  explicit A(const A&) = default;
+};
+
+void func(const A&) { }
+
+void
+test_thread()
+{
+  std::thread t(func, A{});
+  t.join();
+}