3 files changed, 87 insertions, 2 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 08bb6b2baf6..86e26475f51 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,9 @@
+2010-03-02  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	* include/std/mutex (lock_guard::lock_guard): Do not lock mutex when
+	adopt_lock_t constructor is used.
+	* testsuite/30_threads/lock_guard/cons/1.cc: New.
+
 2010-03-02  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* include/bits/stl_bvector.h (hash<vector<bool, _Alloc>>::
diff --git a/libstdc++-v3/include/std/mutex b/libstdc++-v3/include/std/mutex
index 7a1e259fc79..be435cd38e5 100644
--- a/libstdc++-v3/include/std/mutex
+++ b/libstdc++-v3/include/std/mutex
@@ -398,8 +398,8 @@ namespace std
       explicit lock_guard(mutex_type& __m) : _M_device(__m)
       { _M_device.lock(); }
 
-      lock_guard(mutex_type& __m, adopt_lock_t __a) : _M_device(__m)
-      { _M_device.lock(); }
+      lock_guard(mutex_type& __m, adopt_lock_t) : _M_device(__m)
+      { } // calling thread owns mutex
 
       ~lock_guard()
       { _M_device.unlock(); }
diff --git a/libstdc++-v3/testsuite/30_threads/lock_guard/cons/1.cc b/libstdc++-v3/testsuite/30_threads/lock_guard/cons/1.cc
new file mode 100644
index 00000000000..f450d51b80b
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/lock_guard/cons/1.cc
@@ -0,0 +1,79 @@
+// { dg-do run { target *-*-freebsd* *-*-netbsd* *-*-linux* *-*-solaris* *-*-cygwin *-*-darwin* alpha*-*-osf* mips-sgi-irix6* } }
+// { dg-options " -std=gnu++0x -pthread" { target *-*-freebsd* *-*-netbsd* *-*-linux* alpha*-*-osf* mips-sgi-irix6* } }
+// { dg-options " -std=gnu++0x -pthreads" { target *-*-solaris* } }
+// { dg-options " -std=gnu++0x " { target *-*-cygwin *-*-darwin* } }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads "" }
+
+// Copyright (C) 2010 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 <mutex>
+#include <testsuite_hooks.h>
+
+struct Mutex
+{
+  Mutex() : locked(false) { }
+
+  ~Mutex()
+  {
+    if (locked)
+      throw 0;
+  }
+
+  void lock()
+  {
+    if (locked)
+      throw 0;
+    locked = true;
+  }
+
+  void unlock()
+  {
+    if (!locked)
+      throw 0;
+    locked = false;
+  }
+
+  bool locked;
+};
+
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  Mutex m;
+  m.lock();
+
+  try 
+    {
+      std::lock_guard<Mutex> l(m, std::adopt_lock);
+    }
+  catch (...)
+    {
+      VERIFY( false );
+    }
+
+  VERIFY( !m.locked );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}