re PR libstdc++/51845 (23_containers/unordered_multimap/erase/24061-multimap.cc segfault)

	PR libstdc++/51845
	* include/bits/hashtable.h
	(_Hashtable<>::erase(const_iterator, const_iterator)): Also update
	_M_buckets[__n_bkt] if __is_bucket_begin.

	* testsuite/23_containers/unordered_multimap/erase/51845-multimap.cc:
	New test.

From-SVN: r183300

libstdc++-v3/ChangeLog

+2012-01-19  Jakub Jelinek  <jakub@redhat.com>
+
+	PR libstdc++/51845
+	* include/bits/hashtable.h
+	(_Hashtable<>::erase(const_iterator, const_iterator)): Also update
+	_M_buckets[__n_bkt] if __is_bucket_begin.
+	* testsuite/23_containers/unordered_multimap/erase/51845-multimap.cc:
+	New test.
+
 2012-01-18  Benjamin Kosnik  <bkoz@redhat.com>
 
 	* acinclude (GLIBCXX_CONFIGURE_DOCBOOK): Fix quoting.

libstdc++-v3/include/bits/hashtable.h

@@ -1544,7 +1544,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  __bkt = __n_bkt;
 	}
 
-      if (__n && __n_bkt != __bkt)
+      if (__n && (__n_bkt != __bkt || __is_bucket_begin))
 	_M_buckets[__n_bkt] = __prev_n;
       __prev_n->_M_nxt = __n;
       return iterator(__n);

libstdc++-v3/testsuite/23_containers/unordered_multimap/erase/51845-multimap.cc

+// { dg-options "-std=gnu++0x" }
+
+// 2012-01-19  Jakub Jelinek  <jakub@redhat.com>
+//
+// Copyright (C) 2012 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/>.
+
+#include <unordered_map>
+#include <testsuite_hooks.h>
+
+// libstdc++/51845
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  typedef std::unordered_multimap<int, int> Mmap;
+  typedef Mmap::iterator       iterator;
+  typedef Mmap::const_iterator const_iterator;
+  typedef Mmap::value_type     value_type;
+
+  Mmap mm1;
+
+  mm1.insert(value_type(11135, 1));
+  mm1.insert(value_type(11135, 17082));
+  mm1.insert(value_type(9644, 24135));
+  mm1.insert(value_type(9644, 9644));
+  mm1.insert(value_type(13984, 19841));
+  mm1.insert(value_type(9644, 1982));
+  mm1.insert(value_type(13984, 1945));
+  mm1.insert(value_type(7, 1982));
+  mm1.insert(value_type(7, 1945));
+  VERIFY( mm1.size() == 9 );
+
+  iterator it1 = mm1.begin();
+  ++it1;
+  iterator it2 = it1;
+  ++it2;
+  ++it2;
+  iterator it3 = mm1.erase(it1, it2);
+  VERIFY( mm1.size() == 7 );
+  VERIFY( it3 == it2 );
+  VERIFY( *it3 == *it2 );
+
+  const_iterator it4 = mm1.begin();
+  ++it4;
+  const_iterator it5 = it4;
+  ++it5;
+  const_iterator it6 = mm1.erase(it4);
+  VERIFY( mm1.size() == 6 );
+  VERIFY( it6 == it5 );
+  VERIFY( *it6 == *it5 );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}