https://bugs.winehq.org/show_bug.cgi?id=49162
--- Comment #9 from Dmitry Timoshkov dmitry@baikal.ru --- (In reply to Zebediah Figura from comment #8)
Incidentally, it works perfectly in stubless mode, on both Wine and Windows. If you were testing with MIDL and default options, that may be why.
I started working with widl and later switched to midl for testing purposes, and for midl I decided to reproduce widl behaviour as much as possible, as a result I used 'midl /Os' since it's the default (and looks like preferable) setting for widl.