[SR-14718] Building PackageDescription on Linux gives warning: module 'Foundation' was not compiled with library evolution support

[benlangmuir]

Previous ID	SR-14718
Radar	rdar://problem/78827075
Original Reporter	@benlangmuir
Type	Bug
Status	Resolved
Resolution	Done

Environment

Swift Docker tag swift:5.4.1

Additional Detail from JIRA

Votes	0
Component/s	Package Manager
Labels	Bug
Assignee	@abertelrud
Priority	Medium

md5: c45978a9bcc03cd70fb0898f8c80d7e6

Issue Description:

Building the PackageDescription module from swiftpm's main branch on Linux gives

/home/docker_user/src/lsp/sourcekit-lsp/.build/checkouts/swift-package-manager/Sources/PackageDescription/PackageDescription.swift:19:8: warning: module 'Foundation' was not compiled with library evolution support; using it means binary compatibility for 'PackageDescription' can't be guaranteed
import Foundation
       ^ 

This was seen while building sourcekit-lsp with the following patch to add a dependency on PackageDescription: swiftlang/sourcekit-lsp#405

[abertelrud]

@swift-ci create

[abertelrud]

This is almost certainly due to a recent fix to allow PackageDescription and PackagePlugin to be built from source using SwiftPM itself, so they can be built Universal on Darwin platforms. This required adding `--enable-library-evolution` to the target declaration for PackageDescription and PackagePlugin.

This interacts badly with an unintentional reexporting of Foundation symbols in PackageDescription, which was fixed in #3404 but then had to be reverted in #3476. At least until we can reintroduce that fix, we probably will need to disable library evolution on non-Darwin platforms here.

[abertelrud]

Fixed in 6e7bb87