[patch] libstdc++/65085 move-constructor doesn't terminate empty string

[Jonathan Wakely]

Tested x86_64-linux, committed to trunk.

commit 4946abe1a615343a462a86afc633f9681864becf
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Tue Feb 17 10:51:55 2015 +0000

    	PR libstdc++/65085
    	* include/bits/basic_string.h (basic_string(basic_string&&)): Ensure
    	empty string gets null-terminated.
    	* testsuite/21_strings/basic_string/cons/char/65085.cc: New.

diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index 71a47f5..3b2603f 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -476,9 +476,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       {
 	if (__str._M_is_local())
 	  {
-	    if (__str.length())
-	      traits_type::copy(_M_local_buf, __str._M_local_buf,
-				_S_local_capacity + 1);
+	    traits_type::copy(_M_local_buf, __str._M_local_buf,
+			      _S_local_capacity + 1);
 	  }
 	else
 	  {
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/65085.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/65085.cc
new file mode 100644
index 0000000..609f7be
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/65085.cc
@@ -0,0 +1,40 @@
+// 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++11" }
+
+#include <string>
+#include <new>
+#include <cstring>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  std::string s;
+  char buf[sizeof(std::string)];
+  std::memset(buf, 0xff, sizeof(buf));
+  std::string* p = ::new(buf) std::string(std::move(s));
+  VERIFY((*p)[0] == '\0');
+  p->~basic_string();
+}
+
+int
+main()
+{
+  test01();
+}