[v3] implement LWG 2067 and new issues with constructors in <future>

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

This patch implements
http://lwg.github.com/issues/lwg-active.html#2067 which has Ready
status, as well as fixing two new issues I've reported in the past few
hours.  The first is that packaged_task's template constructors should
be restricted to prevent them from being chosen to copy a
packaged_task object and the second is that promise and packaged_task
should properly support uses-allocator construction so that if
"promise(args...)" is well-formed then so is "promise(allocator_arg,
alloc, args...)"

        * include/std/future (promise): Add constructors for uses-allocator
        construction from rvalue promise.
        (packaged_task): Implement LWG 2067. Add additional constructors for
        uses-allocator construction.
        * testsuite/30_threads/packaged_task/cons/3.cc: New.
        * testsuite/30_threads/packaged_task/cons/alloc2.cc: New.
        * testsuite/30_threads/promise/cons/alloc2.cc: New.

Tested x86_64-linux, committed to trunk.

Index: include/std/future
===================================================================
--- include/std/future	(revision 180749)
+++ include/std/future	(working copy)
@@ -955,6 +955,12 @@
 	  _M_storage(__future_base::_S_allocate_result<_Res>(__a))
         { }
 
+      template<typename _Allocator>
+        promise(allocator_arg_t, const _Allocator&, promise&& __rhs)
+        : _M_future(std::move(__rhs._M_future)),
+	  _M_storage(std::move(__rhs._M_storage))
+        { }
+
       promise(const promise&) = delete;
 
       ~promise()
@@ -1047,6 +1053,12 @@
 	  _M_storage(__future_base::_S_allocate_result<_Res&>(__a))
         { }
 
+      template<typename _Allocator>
+        promise(allocator_arg_t, const _Allocator&, promise&& __rhs)
+        : _M_future(std::move(__rhs._M_future)),
+	  _M_storage(std::move(__rhs._M_storage))
+        { }
+
       promise(const promise&) = delete;
 
       ~promise()
@@ -1122,6 +1134,12 @@
 	  _M_storage(__future_base::_S_allocate_result<void>(__a))
         { }
 
+      template<typename _Allocator>
+        promise(allocator_arg_t, const _Allocator&, promise&& __rhs)
+        : _M_future(std::move(__rhs._M_future)),
+	  _M_storage(std::move(__rhs._M_storage))
+        { }
+
       promise(const promise&) = delete;
 
       ~promise()
@@ -1270,6 +1288,15 @@
         { return std::forward<_Tp>(__t); }
     };
 
+  template<typename _Task, typename _Fn, bool
+           = is_same<_Task, typename remove_reference<_Fn>::type>::value>
+    struct __is_same_pkgdtask
+    { typedef void __type; };
+
+  template<typename _Task, typename _Fn>
+    struct __is_same_pkgdtask<_Task, _Fn, true>
+    { };
+
   /// packaged_task
   template<typename _Res, typename... _ArgTypes>
     class packaged_task<_Res(_ArgTypes...)>
@@ -1281,13 +1308,20 @@
       // Construction and destruction
       packaged_task() noexcept { }
 
-      template<typename _Fn>
+      template<typename _Allocator>
         explicit
+        packaged_task(allocator_arg_t, const _Allocator& __a) noexcept
+        { }
+
+      template<typename _Fn, typename = typename
+               __is_same_pkgdtask<packaged_task, _Fn>::__type>
+        explicit
         packaged_task(_Fn&& __fn)
         : _M_state(std::make_shared<_State_type>(std::forward<_Fn>(__fn)))
         { }
 
-      template<typename _Fn, typename _Allocator>
+      template<typename _Fn, typename _Allocator, typename = typename
+               __is_same_pkgdtask<packaged_task, _Fn>::__type>
         explicit
         packaged_task(allocator_arg_t, const _Allocator& __a, _Fn&& __fn)
         : _M_state(std::allocate_shared<_State_type>(__a,
@@ -1301,13 +1335,24 @@
       }
 
       // No copy
-      packaged_task(packaged_task&) = delete;
-      packaged_task& operator=(packaged_task&) = delete;
+      packaged_task(const packaged_task&) = delete;
+      packaged_task& operator=(const packaged_task&) = delete;
 
+      template<typename _Allocator>
+        explicit
+        packaged_task(allocator_arg_t, const _Allocator&,
+                      const packaged_task&) = delete;
+
       // Move support
       packaged_task(packaged_task&& __other) noexcept
       { this->swap(__other); }
 
+      template<typename _Allocator>
+        explicit
+        packaged_task(allocator_arg_t, const _Allocator&,
+                      packaged_task&& __other) noexcept
+        { this->swap(__other); }
+
       packaged_task& operator=(packaged_task&& __other) noexcept
       {
         packaged_task(std::move(__other)).swap(*this);
Index: testsuite/30_threads/packaged_task/cons/alloc2.cc
===================================================================
--- testsuite/30_threads/packaged_task/cons/alloc2.cc	(revision 0)
+++ testsuite/30_threads/packaged_task/cons/alloc2.cc	(revision 0)
@@ -0,0 +1,40 @@
+// { dg-do compile }
+// { dg-options "-std=gnu++0x" }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads "" }
+// { dg-require-atomic-builtins "" }
+
+// Copyright (C) 2011 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/>.
+
+// Test that packaged_task can be default-constructed or move-constructed
+// in a context that does uses-allocator construction.
+
+#include <future>
+#include <memory>
+#include <tuple>
+
+using std::packaged_task;
+using std::allocator_arg;
+using std::allocator;
+using std::tuple;
+
+typedef packaged_task<void()> task;
+allocator<task> a;
+
+tuple<task> t1{ allocator_arg, a };
+tuple<task> t2{ allocator_arg, a, task{} };
Index: testsuite/30_threads/packaged_task/cons/3.cc
===================================================================
--- testsuite/30_threads/packaged_task/cons/3.cc	(revision 0)
+++ testsuite/30_threads/packaged_task/cons/3.cc	(revision 0)
@@ -0,0 +1,56 @@
+// { dg-do run { target *-*-freebsd* *-*-netbsd* *-*-linux* *-*-solaris* *-*-cygwin *-*-darwin* alpha*-*-osf* mips-sgi-irix6* } }
+// { dg-options " -std=gnu++0x -pthread" { target *-*-freebsd* *-*-netbsd* *-*-linux* alpha*-*-osf* mips-sgi-irix6* } }
+// { dg-options " -std=gnu++0x -pthreads" { target *-*-solaris* } }
+// { dg-options " -std=gnu++0x " { target *-*-cygwin *-*-darwin* } }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads "" }
+// { dg-require-atomic-builtins "" }
+
+// Copyright (C) 2011 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/>.
+
+// LWG 2067. packaged_task should have deleted copy c'tor with const parameter
+
+#include <future>
+#include <thread>
+#include <testsuite_hooks.h>
+
+template<typename F>
+std::future<typename std::result_of<F()>::type> spawn_task(F f)
+{
+  typedef typename std::result_of<F()>::type result_type;
+  std::packaged_task<result_type()> task(std::move(f));
+  std::future<result_type> res(task.get_future());
+  std::thread(std::move(task)).detach();
+  return res;
+}
+
+int get_res()
+{
+  return 42;
+}
+
+void test01()
+{
+  auto f = spawn_task(get_res);
+  VERIFY( f.get() == get_res() );
+}
+
+int main()
+{
+  test01();
+}
Index: testsuite/30_threads/promise/cons/alloc2.cc
===================================================================
--- testsuite/30_threads/promise/cons/alloc2.cc	(revision 0)
+++ testsuite/30_threads/promise/cons/alloc2.cc	(revision 0)
@@ -0,0 +1,42 @@
+// { dg-do compile }
+// { dg-options "-std=gnu++0x" }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads "" }
+// { dg-require-atomic-builtins "" }
+
+// Copyright (C) 2011 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/>.
+
+// Test that promise can be default-constructed or move-constructed
+// in a context that does uses-allocator construction.
+
+#include <future>
+#include <memory>
+#include <tuple>
+
+using std::promise;
+using std::allocator_arg;
+using std::allocator;
+using std::tuple;
+
+typedef promise<int>  p;
+typedef promise<int&> pr;
+typedef promise<void> pv;
+allocator<p> a;
+
+tuple<p, pr, pv> t1{ allocator_arg, a };
+tuple<p, pr, pv> t2{ allocator_arg, a, p{}, pr{}, pv{} };