[Lazarus] Failure to recompile with a different define

[Giuliano Colla]

I have two Lazarus projects, let's call them project A and project B, 
which share the same sources, only with a different define: let's say 
-dProjA and -dProjB.

If, starting from a clean situation, I compile first project A, and then 
project B, most of the modules aren't recompiled, and I end up with a 
project B built with a mix-up of units, some compiled with project A 
define and some compiled with project B define.

I managed to find a way out: setting different unit paths for project A 
and project B solves the issue, but this situation may be rather 
confusing for an inexperienced user.

IMHO this is not a very unusual setup: it applies to any situation where 
the same base project must provide different options or features.

Is this a Lazarus issue or rather an fpc issue? Do ppu's include the 
defines used for compilation? If not, wouldn't it be advisable to add 
them somehow?

Giuliano