Add noexcept to std::function swap

	PR libstdc++/77322
	* doc/xml/manual/intro.xml: Document DR 2062 change.
	* include/std/functional (function::swap): Add noexcept.
	(swap(function<Res(Args...)&, function<Res(Args...)&)): Likewise.
	* testsuite/20_util/function/77322.cc: New test.

From-SVN: r239662

libstdc++-v3/ChangeLog

+2016-08-22  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/77322
+	* doc/xml/manual/intro.xml: Document DR 2062 change.
+	* include/std/functional (function::swap): Add noexcept.
+	(swap(function<Res(Args...)&, function<Res(Args...)&)): Likewise.
+	* testsuite/20_util/function/77322.cc: New test.
+
 2016-08-19  Jonathan Wakely  <jwakely@redhat.com>
 
 	* testsuite/21_strings/basic_string/pthread18185.cc: Use -pthread for

libstdc++-v3/doc/xml/manual/intro.xml

@@ -850,6 +850,12 @@ requirements of the license of GCC.
     <listitem><para>Add additional overloads.
     </para></listitem></varlistentry>
 
+    <varlistentry><term><link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="../ext/lwg-defects.html#2062">2062</link>:
+	<emphasis>2062. Effect contradictions w/o no-throw guarantee of <code>std::function</code> swaps</emphasis>
+    </term>
+    <listitem><para>Add <code>noexcept</code> to swap functions.
+    </para></listitem></varlistentry>
+
     <varlistentry><term><link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="../ext/lwg-defects.html#2063">2063</link>:
 	<emphasis>Contradictory requirements for string move assignment</emphasis>
     </term>

libstdc++-v3/include/std/functional

@@ -1922,7 +1922,7 @@ _GLIBCXX_MEM_FN_TRAITS(&&, false_type, true_type)
        *  Swap the targets of @c this function object and @a __f. This
        *  function will not throw an %exception.
        */
-      void swap(function& __x)
+      void swap(function& __x) noexcept
       {
 	std::swap(_M_functor, __x._M_functor);
 	std::swap(_M_manager, __x._M_manager);
@@ -2124,9 +2124,11 @@ _GLIBCXX_MEM_FN_TRAITS(&&, false_type, true_type)
    *
    *  This function will not throw an %exception.
    */
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 2062. Effect contradictions w/o no-throw guarantee of std::function swaps
   template<typename _Res, typename... _Args>
     inline void
-    swap(function<_Res(_Args...)>& __x, function<_Res(_Args...)>& __y)
+    swap(function<_Res(_Args...)>& __x, function<_Res(_Args...)>& __y) noexcept
     { __x.swap(__y); }
 
 

libstdc++-v3/testsuite/20_util/function/77322.cc

+// Copyright (C) 2016 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/>.
+
+// { dg-do compile { target c++11 } }
+
+#include <functional>
+
+// PR libstdc++/77322
+std::function<void()> f, g;
+static_assert( noexcept(f.swap(g)), "member swap is noexcept" );
+static_assert( noexcept(swap(f, g)), "non-member swap is noexcept" );