name conflicts with PROPVARIANT, propidl.idl and #import

[peterchen]

I'm currently moving our VC6 code base to VC7 (and test against VC8
Beta).

I have major problems #importing .idl files that use PROPVARIANT's.
I already played with different #import options (rename, exclude,
auto_rename, #defining the tag_inner_PROPVARIANT to PROPVARIANT etc.),
but with limited success. Either the PROPVARIANT used in the .tlh/.tli
interface wrappers is declared as a separate type from the "Windows"
type, or I have conflicting declarations.

This is complicated by a wrapper class (propvar_t) class being derived
from PROPVARIANT.
(One declaraiton makes PROPVARIANT a union, which you can't inherit
from)

Abstract:

// ---- .idl ---------
import "propidl.idl"; // added for VC7+
[...] interface IFoo : IUnknown
{
HRESULT Foo(PROPVARIANT pv);
};
....

// ---- .h ---------
#import "foo.tlb" rename_namespace("nsFoo") ...
class _propvar_t : public PROPVARIANT
{
// ...
// type cast operators and conversion constructors
};

// ---- .cpp ---------

IFooPtr pFoo;
pFoo.CreateInstance(__uuidof(Foo));

propvar_t pv(42l);
pFoo->Foo(pv);

// -------------------
Any help?

TIA
Peter