Re: VC8 Compiler bizarreness

From:
"Alex Blekhman" <tkfx.REMOVE@yahoo.com>
Newsgroups:
microsoft.public.vc.language
Date:
Wed, 4 Jun 2008 22:01:14 +0300
Message-ID:
<OkXYoTnxIHA.4500@TK2MSFTNGP04.phx.gbl>
"Murrgon" wrote:

I think that the culprit is `GTL::TSmartPtr<TYPE>' template.


It does define operator!=(), but the classes it's suggesting as
the TYPE
don't.


The non relevant classes are te quirk of Koenig lookup that
compiler tries to perform. It founds a lot of other `operator !='
in different namespaces however fails to match the arguments. The
real error is with TSmartPtr. See comments inline.

[...]
    TBool operator!=(TYPE* ptr)
    {
      return(m_pRefCountObject != ptr);
    }


The above function must be const. Compilation fails because
compiler cannot find appropriate const `operator !=' function for
the statement "kObject != ptr".

    friend INL TBool operator!=(TYPE* ptr, const
TSmartPtr<TYPE>& kObject)
    {
      return(kObject != ptr);
    }


As you can see, global `operatpr !=' accepts kObject parameter as
constant reference. Compiler cannot call non-constant function on
this reference in return statement. So, the fix is:

TBool operator!=(const TYPE* ptr) const
{
  return(m_pRefCountObject != ptr);
}

I added another `const' qualifier for `ptr' parameter, so the
operator is more generous about its input. Also, you should fix
other member functions and operators of `TSmartPtr' class, so if a
function does not change the object it have to be qualified as
const. Global operator should accept const values, too.

HTH
Alex

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