LWG Issue 2097: packaged_task constructors should be constrained

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@192544 91177308-0d34-0410-b5e6-96231b3b80d8

include/future

@@ -2013,10 +2013,26 @@ public:
     // construction and destruction
     _LIBCPP_INLINE_VISIBILITY
     packaged_task() _NOEXCEPT : __p_(nullptr) {}
-    template <class _Fp>
+    template <class _Fp,
+              class = typename enable_if
+              <
+                  !is_same<
+                      typename decay<_Fp>::type, 
+                      packaged_task
+                      >::value
+                  >::type
+             >
         _LIBCPP_INLINE_VISIBILITY
         explicit packaged_task(_Fp&& __f) : __f_(_VSTD::forward<_Fp>(__f)) {}
-    template <class _Fp, class _Allocator>
+    template <class _Fp, class _Allocator,
+              class = typename enable_if
+              <
+                  !is_same<
+                      typename decay<_Fp>::type, 
+                      packaged_task
+                      >::value
+                  >::type
+              >
         _LIBCPP_INLINE_VISIBILITY
         explicit packaged_task(allocator_arg_t, const _Allocator& __a, _Fp&& __f)
              : __f_(allocator_arg, __a, _VSTD::forward<_Fp>(__f)),
@@ -2128,10 +2144,26 @@ public:
     // construction and destruction
     _LIBCPP_INLINE_VISIBILITY
     packaged_task() _NOEXCEPT : __p_(nullptr) {}
-    template <class _Fp>
+    template <class _Fp,
+              class = typename enable_if
+              <
+                  !is_same<
+                      typename decay<_Fp>::type, 
+                      packaged_task
+                      >::value
+                  >::type
+              >
         _LIBCPP_INLINE_VISIBILITY
         explicit packaged_task(_Fp&& __f) : __f_(_VSTD::forward<_Fp>(__f)) {}
-    template <class _Fp, class _Allocator>
+    template <class _Fp, class _Allocator,
+              class = typename enable_if
+              <
+                  !is_same<
+                      typename decay<_Fp>::type, 
+                      packaged_task
+                      >::value
+                  >::type
+              >    
         _LIBCPP_INLINE_VISIBILITY
         explicit packaged_task(allocator_arg_t, const _Allocator& __a, _Fp&& __f)
              : __f_(allocator_arg, __a, _VSTD::forward<_Fp>(__f)),

test/thread/futures/futures.tas/futures.task.members/ctor1.fail.cpp

@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <future>
+
+// class packaged_task<R(ArgTypes...)>
+// template <class F>
+//   packaged_task(F&& f);
+// These constructors shall not participate in overload resolution if 
+//    decay<F>::type is the same type as std::packaged_task<R(ArgTypes...)>.
+
+#include <future>
+#include <cassert>
+
+struct A {};
+typedef std::packaged_task<A(int, char)> PT;
+typedef volatile std::packaged_task<A(int, char)> VPT;
+
+
+int main()
+{
+    PT p { VPT{} };
+}

test/thread/futures/futures.tas/futures.task.members/ctor2.fail.cpp

@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <future>
+
+// class packaged_task<R(ArgTypes...)>
+// template <class F, class Allocator>
+//   explicit packaged_task(allocator_arg_t, const Allocator& a, F&& f);
+// These constructors shall not participate in overload resolution if 
+//    decay<F>::type is the same type as std::packaged_task<R(ArgTypes...)>.
+
+#include <future>
+#include <cassert>
+
+#include "../../test_allocator.h"
+
+struct A {};
+typedef std::packaged_task<A(int, char)> PT;
+typedef volatile std::packaged_task<A(int, char)> VPT;
+
+int main()
+{
+    PT p { std::allocator_arg_t{}, test_allocator<A>{}, VPT {}};
+}

test/thread/thread.threads/thread.thread.class/thread.thread.constr/constr.fail.cpp

@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <thread>
+
+// class thread
+//     template <class _Fp, class ..._Args,
+//         explicit thread(_Fp&& __f, _Args&&... __args);
+//  This constructor shall not participate in overload resolution 
+//       if decay<F>::type is the same type as std::thread.
+
+
+#include <thread>
+#include <cassert>
+
+int main()
+{
+    volatile std::thread t1;
+    std::thread t2 ( t1, 1, 2.0 );
+}