Getting Access violation reading location 0xFFFFFFFFFFFFFFFF when calling EnumTypeDefs? It's a simple fix

[revosw]

It may happen that you get an error that looks something like this:

Exception thrown at 0x00007FFE0E7EF780 (rometadata.dll) in iidtest.exe: 0xC0000005: Access violation reading location 0xFFFFFFFFFFFFFFFF.

The problem is that in the call to EnumTypeDefs, you have accidentally passed the phEnum argument as a 32-bit uint instead of 64-bit uint

// HCORENUM is typedef'd as __int3264 in MSVC, in other words 32-bit on 32-bit OS and 64-bit on 64-bit OS. but here we're saying that enum_typedef should be a 32-bit integer, and you are very likely to be on a 64-bit OS.
ULONG enum_typedef = NULL;
UINT32 next_type_def = 0;
mdImport->lpVtbl->EnumTypeDefs(mdImport, &enum_typedef, &next_type_def, 1, NULL)

Hope this saves you 5 hours of wtf, which I'll never get back