FIX: CComVariant > and < Operators Cause LNK2001 Errors

This article was previously published under Q191626
This article has been archived. It is offered "as is" and will no longer be updated.
SYMPTOMS
If you use the "greater than" (>) or "less than" (<) comparison operators for CComVariant, you receive the following linker error:
error LNK2001: unresolved external symbol _VarCmp@12
CAUSE
You use VarCmp() to compare two VARIANTS. This function is supposed totake four arguments. The declaration for VarCmp() in Oleauto.h isincorrect, and it takes only three arguments. ATL also calls VarCmp()incorrectly with three arguments in CComVariant::operator < andCComVariant::operator >.
RESOLUTION
In OLEAUTO.H, change the declaration for VarCmp() from:
STDAPI VarCmp(LPVARIANT pvarLeft, LPVARIANT pvarRight, LCID lcid);				
to the following:
STDAPI VarCmp(LPVARIANT pvarLeft, LPVARIANT pvarRight, LCID lcid,                 ULONG dwFlags);				
In Atlbase.h, change the calls to VarCmp() by passing in a fourth argumentof zero. Change the code from:
bool operator<(const VARIANT& varSrc) const{   return VarCmp((VARIANT*)this, (VARIANT*)&varSrc,                 LOCALE_USER_DEFAULT)==VARCMP_LT;}bool operator>(const VARIANT& varSrc) const{   return VarCmp((VARIANT*)this, (VARIANT*)&varSrc,                 LOCALE_USER_DEFAULT)==VARCMP_GT;}				
to the following:
bool operator<(const VARIANT& varSrc) const{   return VarCmp((VARIANT*)this, (VARIANT*)&varSrc,                 LOCALE_USER_DEFAULT, 0)==VARCMP_LT;}bool operator>(const VARIANT& varSrc) const{   return VarCmp((VARIANT*)this, (VARIANT*)&varSrc,                 LOCALE_USER_DEFAULT, 0)==VARCMP_GT;}				
You must do a "Rebuild All" to bring in the new changes.
STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article. This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed
MORE INFORMATION
VarCmp() is implemented only in a newer version of Oleaut32.dll (2.30.4261or later). If you use the CComVariant > or < operators, you must distribute Oleaut32.dll via Vbrun60.exe. For more information, refer to Redist.wri in the VC98\Redist directory on the Visual C++ CD.
Properties

Article ID: 191626 - Last Review: 01/07/2015 07:11:10 - Revision: 3.0

  • Microsoft ActiveX Template Library 3.0
  • kbnosurvey kbarchive kbbug kbfix kbvs600sp3fix KB191626
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) or "less than" (<) comparison operators for CComVariant, you receive the following linker error: error LNK2001: unresolved external symbol _VarCmp@12 You use VarCmp() to compare two VARIANTS. This function is..." />
) or "less than" (<) comparison operators for CComVariant, you receive the following linker error: error LNK2001: unresolved external symbol _VarCmp@12 You use VarCmp() to compare two VARIANTS. This function is..." />