[v3 patch] Fix self-assignment in std::experimental::any

[Jonathan Wakely <jwakely at redhat dot com>]

When I fixed any's copying of non-trivial types I broke the
self-assignment case. This adds an explicit check for it.

Thanks to Axel Menzel for noticing the bug.

Tested ppc64le-linux, committed to trunk.

commit 8a9db2d69b88c72ca0fd794c1058918069787f83
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Jul 30 10:11:28 2015 +0100

    	* include/experimental/any (any::operator=(const any&)): Check for
    	self-assignment.
    	* testsuite/experimental/any/assign/self.cc: New.
    	* testsuite/experimental/any/misc/any_cast_neg.cc: Adjust dg-error.

diff --git a/libstdc++-v3/include/experimental/any b/libstdc++-v3/include/experimental/any
index 7b5e5ec..fbb70a7 100644
--- a/libstdc++-v3/include/experimental/any
+++ b/libstdc++-v3/include/experimental/any
@@ -175,6 +175,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     /// Copy the state of another object.
     any& operator=(const any& __rhs)
     {
+      if (this == &__rhs)
+	return *this;
+
       if (__rhs.empty())
 	clear();
       else
diff --git a/libstdc++-v3/testsuite/experimental/any/assign/self.cc b/libstdc++-v3/testsuite/experimental/any/assign/self.cc
new file mode 100644
index 0000000..0fb9566
--- /dev/null
+++ b/libstdc++-v3/testsuite/experimental/any/assign/self.cc
@@ -0,0 +1,41 @@
+// Copyright (C) 2015 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-options "-std=gnu++14" }
+
+#include <experimental/any>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  using std::experimental::any;
+
+  any a;
+  a = a;
+  VERIFY( a.empty() );
+
+  a = 1;
+  a = a;
+  VERIFY( !a.empty() );
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/experimental/any/misc/any_cast_neg.cc b/libstdc++-v3/testsuite/experimental/any/misc/any_cast_neg.cc
index 39e3226..b88592a 100644
--- a/libstdc++-v3/testsuite/experimental/any/misc/any_cast_neg.cc
+++ b/libstdc++-v3/testsuite/experimental/any/misc/any_cast_neg.cc
@@ -26,5 +26,5 @@ void test01()
   using std::experimental::any_cast;
 
   const any y(1);
-  any_cast<int&>(y); // { dg-error "qualifiers" "" { target { *-*-* } } 356 }
+  any_cast<int&>(y); // { dg-error "qualifiers" "" { target { *-*-* } } 359 }
 }