PR libstdc++/84532 prevent unwrapping of reference_wrapper arguments

	PR libstdc++/84532
	* include/std/thread (thread::__make_invoker): Construct tuple
	directly instead of using make_tuple.
	* testsuite/30_threads/async/84532.cc: New.
	* testsuite/30_threads/thread/84532.cc: New.

From-SVN: r257956

libstdc++-v3/ChangeLog

+2018-02-23  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/84532
+	* include/std/thread (thread::__make_invoker): Construct tuple
+	directly instead of using make_tuple.
+	* testsuite/30_threads/async/84532.cc: New.
+	* testsuite/30_threads/thread/84532.cc: New.
+
 2018-02-20  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/ext/aligned_buffer.h [_GLIBCXX_INLINE_VERSION]

libstdc++-v3/include/std/thread

@@ -243,21 +243,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	{ return _M_invoke(_Indices()); }
       };
 
-    // Alias for _Invoker<tuple<DECAY_COPY(_Tp)...>>
     template<typename... _Tp>
-      using __invoker_type
-	= _Invoker<decltype(std::make_tuple(std::declval<_Tp>()...))>;
+      using __decayed_tuple = tuple<typename std::decay<_Tp>::type...>;
 
   public:
-    // Returns a call wrapper that does
-    // INVOKE(DECAY_COPY(__callable), DECAY_COPY(__args)).
+    // Returns a call wrapper that stores
+    // tuple{DECAY_COPY(__callable), DECAY_COPY(__args)...}.
     template<typename _Callable, typename... _Args>
-      static __invoker_type<_Callable, _Args...>
+      static _Invoker<__decayed_tuple<_Callable, _Args...>>
       __make_invoker(_Callable&& __callable, _Args&&... __args)
       {
-	return { {
-	    std::make_tuple(std::forward<_Callable>(__callable),
-			    std::forward<_Args>(__args)...)
+	return { __decayed_tuple<_Callable, _Args...>{
+	    std::forward<_Callable>(__callable), std::forward<_Args>(__args)...
 	} };
       }
   };

libstdc++-v3/testsuite/30_threads/async/84532.cc

+// { dg-do compile { target c++11 } }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <future>
+
+// PR libstdc++/84532
+
+struct F
+{
+  template<typename T, typename U>
+    void operator()(T, U, int&)
+    {
+      using std::is_same;
+      using std::reference_wrapper;
+      static_assert(is_same<T, reference_wrapper<int>>::value, "");
+      static_assert(is_same<U, reference_wrapper<const int>>::value, "");
+    }
+};
+int i = 0;
+auto fut = std::async(F{}, std::ref(i), std::cref(i), std::ref(i));

libstdc++-v3/testsuite/30_threads/thread/84532.cc

+// { dg-do compile { target c++11 } }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <thread>
+
+// PR libstdc++/84532
+
+struct F
+{
+  template<typename T, typename U>
+    void operator()(T, U, int&)
+    {
+      using std::is_same;
+      using std::reference_wrapper;
+      static_assert(is_same<T, reference_wrapper<int>>::value, "");
+      static_assert(is_same<U, reference_wrapper<const int>>::value, "");
+    }
+};
+int i = 0;
+std::thread t(F{}, std::ref(i), std::cref(i), std::ref(i));