cc @aciidb0mb3r

IIRC we explicitly keep it off for complex indexing related reasons. See:

#1422

@aciidb0mb3r but isn't not having completion much better than not compiling? Do we have a radar for the completion not working?

I don't think we had bugs about not being able to compile with modules was turned off. I see you mentioned having this issue with CAtomics, would be nice if you can include complete reproduction steps. IIRC, it wasn't really a bug with indexing, its just that the SwiftPM's project model doesn't map 1-to-1 with the generated Xcode project. I think #1406 is a good compromise but we need to test it with some community packages to make sure it doesn't break something unexpected.

I landed an enhancement where modules will be enabled when there is an umbrella header in the C target. 7f27fcf

@aciidb0mb3r sorry, I didn't get a notification about your comments. See complete repro instructions in SR-9024 . Or just try adding SwiftNIO as a sub-project to any Xcode proj you created yourself. See also: https://forums.swift.org/t/cant-experiment-swiftnio-in-playground/15020