Ran into a problem with Build vis-a-vis .di files ~ Build sees the module reference, and adds the module to the list of things that dmd should operate upon. However, dmd doesn't like to be handed (command line) references to .di files in any shape or form; and barfs when you try it. In other words, a reference to a .di file must only be loaded implicitly by dmd. I'm not quite sure what to make of that, but there it is.
To get around the issue, one can add a pragma(nolink) to the file, and rename it .d instead of .di, since Build otherwise ignores the .di file completely and adds a .d reference into the list of things to compile (not good).
