[patch] libstdc++/61946 Fix old regression in <ext/rope>

[Jonathan Wakely <jwakely at redhat dot com>]

This has been broken since 4.3.0

Tested x86_64-linux, committed to trunk.

commit 35ba1889a1652eece0b4a3ab07290fcd8dc8f120
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Jul 29 10:06:39 2014 +0100

    	PR libstdc++/61946
    	* include/ext/rope (rope::rope(char_producer<_CharT>*, size_t, bool,
    	const allocator_type&)): Pass non-const allocator to
    	_S_new_RopeFunction.
    	* testsuite/ext/rope/61946.cc: New.

diff --git a/libstdc++-v3/include/ext/rope b/libstdc++-v3/include/ext/rope
index df3d4bb..147b335 100644
--- a/libstdc++-v3/include/ext/rope
+++ b/libstdc++-v3/include/ext/rope
@@ -1544,7 +1544,7 @@ protected:
       typedef typename _Base::allocator_type allocator_type;
       using _Base::_M_tree_ptr;
       using _Base::get_allocator;
-      using _Base::_M_get_allocator;      
+      using _Base::_M_get_allocator;
       typedef __GC_CONST _CharT* _Cstrptr;
       
       static _CharT _S_empty_c_str[1];
@@ -1876,8 +1876,9 @@ protected:
 	   const allocator_type& __a = allocator_type())
       : _Base(__a)
       {
-	this->_M_tree_ptr = (0 == __len) ?
-	  0 : _S_new_RopeFunction(__fn, __len, __delete_fn, __a);
+	this->_M_tree_ptr = (0 == __len)
+	  ? 0
+	  : _S_new_RopeFunction(__fn, __len, __delete_fn, _M_get_allocator());
       }
 
       rope(const rope& __x, const allocator_type& __a = allocator_type())
diff --git a/libstdc++-v3/testsuite/ext/rope/61946.cc b/libstdc++-v3/testsuite/ext/rope/61946.cc
new file mode 100644
index 0000000..ba73b48
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/rope/61946.cc
@@ -0,0 +1,31 @@
+// Copyright (C) 2014 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 }
+
+#include <ext/rope>
+
+struct empty_char_prod : __gnu_cxx::char_producer<char>
+{
+  virtual void operator()(size_t, size_t, char*) {}
+};
+
+int main ()
+{
+  empty_char_prod* ecp = new empty_char_prod;
+  __gnu_cxx::crope excrope( ecp, 10L, true );
+}