[@nashysolutions over on GitHub:]
As you can see, I am wondering around GitHub like a nomad, trying to find out more. You guys know if this issue has been raised already?
There is a bug registered here, although it contains little information because work on it has revolved more around the evolution proposal than the bug report.
The fix is actually already implemented, it’s just not live. I implemented it in this pull request and it was merged. Unfortunately it ran into another bug that mishandles some packages and had to be temporarily disabled and hidden behind a compiler condition (by this pull request). At this point, all the known packages which trigger the bug are confidential. Since I am not cleared to see them, I cannot reproduce the bug and cannot debug it. Apple’s employees have done some debugging of their own and from what they were able to say publicly, it seems the bug might actually have to do with package identity and caching instead, and may have only been exposed by the new code. For now I am crossing my fingers that it might have fixed itself by the time the identity overhaul is complete, and that at that point all we will have to do is remove the compiler condition. I think the most recent discussion is in this pull request, from which you should be able to follow links to find all the others.
It will not be included in Swift 5.4. I am hoping it will be in Swift 5.5.