dmd -H switch and implementation details

[dominik]

I thought -H switch would give a .di file occluding the implementation 
details of functions.
I'm building a dll and I have tried to make a .di file with externs and 
exports in it without implementation (which is obviously in a DLL), however 
I saw implementation being included in .di file.

Is there another switch which makes only a declaration .di without 
definition? Or maybe a separate utility for that?