AcDbObjectId == Operator Causes Crash in Mixed Managed /CLR code

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AcDbObjectId == Operator Causes Crash in Mixed Managed /CLR code

问题：

Any use of the == operator with AcDbObjectId causes a crash in my AutoCAD 2005 or AutoCAD 2006 code.  What can I do to avoid this?  Example:

AcDbObjectId ida, idb;

if(ida == idb)

acutPrintf(_T("Ids Match!"));

解答：

The problem with this code is that the managed compiler has a forward declaration of the class which AcDbObjectId wraps called AcDbStub, which it does not have a managed definition for - but links with an unmanaged module that does.  From MSDN:

"...can occur when there is only a forward declaration for a type in an MSIL module (compiled with /clr), where the type is referenced in the MSIL module, and where the MSIL module is linked with a native module that has a definition for the type."
The quick solution for this is to give the managed code a dummy definition for this wrapped type by adding:

class AcDbStub {};

in your CPP code before the code you use the comparison with.