How to debug ?

[Derix via Digitalmars-d-learn]

OK, I have the newest Eclipse+DDT on Linux.

Debugging capabilies look great :
https://github.com/bruno-medeiros/DDT/blob/latest/documentation/Features.md#debugging-functionality

However so far I haven't been able to step throug source code.
What am I missing ? Is there an option to pass to the compiler ?
Yet another tweak to json.dub ?