First some positive words as I read several criticism about the additional sdl format. I am starting to use it and I feel its really nice, much cleaner to read and write, thanks for the addition.

That being said, unfortunately I don't get subPackage using a subConfiguration to work.

This is the working dub.json
This is the not-working dub.sdl

The configuration "with-derelict-loader" defines the version specifier "ERUPTED_FROM_DERELICT" which is used in both the subPackages (at the bottom of both the dub files).

When running e.g.: dub run erupted:devices the json version runs fine, but the sdl version complaints about undefined identifier 'DerelictErupted'. This identifier is only defined with the version ERUPTED_FROM_DERELICT, hence my guess that this version is not forwarded to dmd.

So what am I doing wrong in the sdl file?