zld is missing the force_load fix in Xcode 11 about zld

[michaeleisel]

Interesting! Yeah this can be fixed

[michaeleisel]

@rmaz you think that the explanation in the Xcode 11 release notes was incorrect? Because I'd like to just copy whatever they did for parity, so even if force loading everything is unnecessary, I'd rather be just as unnecessary as Xcode 11's ld is

[rmaz]

Simplest IMO would be extending the -ObjC code to also check for Swift symbols. The other option would be to first do a pass over the entire archive looking for a Swift symbol to mark the archive as force loadable, but it seemed a little wasteful to do multiple passes for every archive. Thoughts?

[michaeleisel]

Yeah multiple passes seems reasonable. What confuses me is that it says, "Static libraries are now always force-loaded in their entirety during linking". However, when I build a mixed ObjC/Swift static lib, and one of the files is an ObjC category (so it would cause issues unless it's been force loaded), it fails to include it. So it seems like, despite what the release notes say, it probably only forcibly includes at the object file level and not at the static library level. But I've asked for clarification in that swift.org ticket

[michaeleisel]

s/multiple passes/avoiding multiple passes/

[rmaz]

So it seems like, despite what the release notes say, it probably only forcibly includes at the object file level and not at the static library level.

That was my suspicion too, but I have not closely verified. I know it is not doing force_load on all static libraries as our application would be unlinkable in that case. I can confirm that extending the ObjC code path to include Swift symbols works for our code. If you're fine with this approach I can put up a PR tomorrow.

[michaeleisel]

Sure, that'd be great! I can run unit tests on my end, and maybe some perf ones too