Am 16.02.2018 um 11:09 schrieb Jacek Caban <jacek@codeweavers.com>:

In such cases we need to use the second way. Note that uuids are usually defined using DEFINE_GUID in headers, see guiddef.h for the macro. It expands to |extern const GUID| unless DEFINE_GUID is defined. If it's defined, full declaration is included. In wmp_main.c we include initguid.h, which defines DEFINE_GUID macro. It means that we will have uuids declared for all headers included in wmp_main.c.
Wouldn't it be possible to include public headers that have GUIDs from uuid.lib, then include initguid.h, and then include headers that define WMP guids (or define the WMP GUIDs manually)? That should import guids that work with uuid.lib from there and define the rest.

Of course the beauty of a half-way approach is always questionable, so not sure if that's better than just using DEFINE_GUID for everything.