What does error: 'spi-builder-workspace': Invalid manifest mean?

[heckj]

Morning - I was digging around in my build logs (example in question: https://swiftpackageindex.com/builds/967AC3B8-B943-4910-B7BD-27AA3EBEF53B) and saw that Swift 5.7 - in particular - (not Swift 5.6 or Swift 5.8) was failing to build for this package.

The swift error is that when it's parsing Package.swift, it can't resolve the symbol for ProcessInfo, which I'm using within the package to adjust the settings based on environment variables. But while I was noodling on that, I noticed the error above it:

error: 'spi-builder-workspace': Invalid manifest

And wasn't sure what was happening. Is there a builder that's gone awry, or a flaw in an .spi file? It's not happening with other versions of builders (Swift 5.8, etc) - but I don't know how they're segmented, and what might be happening with this error.

[finestructure]

I can't check right now but shouldn't it also do import Foundation and not just check canImport?

  #if canImport(Foundation)
    import Foundation // this here?
    if ProcessInfo.processInfo.environment["CI"] != nil {
        globalSwiftSettings.append(.unsafeFlags(["-Xfrontend", "-strict-concurrency=complete"]))

[finestructure]

(no idea why that would happen only on 5.7 though, if that's indeed the problem)

[heckj]

The #if canImport() nonsense was a vague attempt to see if i was making a crap assumption on Swift 5.7 - it's working on all the other versions, which is really throwing me sideways. But yeah, I should just explicitly import Foundation and see how it rolls.

[heckj]

Adding the explicit "import Foundation" sorted the whole thing for Swift 5.7 - lord knows why only that one, and not Swift 5.6 or Swift 5.8 or later. I guess there was a quirky scenario where Foundation wasn't implicitly imported (it typically is on macOS, but not on iOS or Linux)