I've just discovered the msclr::lock class in the C++ Support Library online
documentation.  This seems like a much cleaner way to implement thread
protection than using monitor::enter/try/finally/monitor exit.  However, I
cannot get around one of the warning messages and am requesting help in
understanding what is causing the warning.

All of the online sample code for the class msclr::lock generates the same
warning message.   I have provide simplified code below that generates the
same warning message.  The problem appears to be related to the typedef
'is_not' in the msclr::lock constructor.  Can anyone help me out and explain
why this warning is occurring and how to work around it.  I have limited
working experience with templates and this is the first time I've come
across a case where the class constructors are declared as templates but the
class isself is not. Can anyone explain what the warning means and what I
must do to avoid this warning message?  I am working with VS2005, WinXP Pro
(SP2) and have the compiler warning level is set to 3.

Thanks for any and all help

Ian

SAMPLE CODE THAT GENERATES THE WARNING MESSAGE
================================================
#include "stdafx.h"
#include <msclr/lock.h>

using namespace System;

int main()
{
   Object ^pObject = gcnew Object();
   msclr::lock oL( pObject );
}

COMPILER WARNING MESSAGE
==========================
C:\Program Files\Microsoft Visual Studio 8\VC\include\msclr/lock.h(51) :
warning C4091: '' : ignored on left of 'int' when no variable is declared
.\testCPPConsoleApplication.cpp(12) : see reference to function template
instantiation 'msclr::lock::lock<System::Object>(T ^)' being compiled
with
[
T=System::Object
]

PARTS IN CLASS 'MSCLR::LOCK' THAT PRODUCE THE WARNING
===============================================
namespace msclr
{
   ref class lock
       {
       private:
           System::Object ^ m_object;
           bool m_locked;

           template<class T,class U> value struct is_not { typedef int
__dont_use_this_type__; };

       public:
           template<class T> lock( T ^ _object)
               : m_object( _object ),
                 m_locked( false )
           {
               // ensure that T is not a ReaderWriterLock.
               is_not<T,
System::Threading::ReaderWriterLock>::__dont_use_this_type__;
               acquire(System::Threading::Timeout::Infinite);
           }

    ... remainder of class definition...
};