subdir_done is not working inside a condition

[xclaesse]

IMO the whole point of subdir_done is to do something like this:

if not dep.found()
  subdir_done()
endif
executable('app', dependencies : dep)

But it's not working, and app fails to build because dep is not found.

[tp-m]

Yes, ran into this too the other day. Renders subdir_done() a bit useless.

Can easily be reproduced by modifying the unit test to put it into an if true block.