Set -user-module-version for any version-based package

[neonichu]

This would allow conditionalizing client code using #if canImport(:_version:) so that different versions of a dependency can be supported within a single codebase.

Note: this is explicitly not passing the flag if pre-releases are in use to avoid any confusion in those cases.

rdar://107077287

[neonichu]

@swift-ci please smoke test

[neonichu]

Unsure whether we should conditionalize this based on tools-version

[tomerd]

Unsure whether we should conditionalize this based on tools-version

probably should for unintended consequences? or is it inert?

also should we add a test?

[neonichu]

probably should for unintended consequences? or is it inert?

What is was thinking is that not tying it to the tools version would allow folks to support multiple versions if their users are using a newer SwiftPM, but they would still have support for a singular older version for users of older SwiftPMs.

For example, in the case of a Swift macro, I could write something like:

#if canImport(SwiftSyntax _version: 510.0.0)
...
#else
...
#endif

where the else block would still work for users of Swift 5.9 who by definition won't be able to use the swift-syntax aligned with 5.10 and therefore couldn't even reach the if anyway.

It does come with a certain danger of course, because presumably the package would have a more open ended dependency and it would rely on clients to constraint their dependencies in some way.

[neonichu]

also should we add a test?

We should, but it doesn't look like the infrastructure of the build plan tests supports it today. The version of any dependency seems to not be set when running those tests.

[neonichu]

Ah, it seems like we can just hardcode a version in the Manifest.createLocalSourceControlManifest() call, but we don't really resolve anything, so we currently don't.

[neonichu]

We're currently discussing whether we should bring this into 5.9, so for now I set it to be included for any package with tools-version 5.9 or newer.

[neonichu]

@swift-ci please smoke test

[neonichu]

@swift-ci please smoke test windows

[neonichu]

[157/171] Compiling BuildTests BuildPlanTests.swift
/Users/ec2-user/jenkins/workspace/swift-package-manager-with-xcode-self-hosted-PR-osx/branch-main/swiftpm/Tests/BuildTests/BuildPlanTests.swift:4917:62: error: 'contains' is only available in macOS 13.0 or newer
            XCTAssertTrue(try swiftTarget.compileArguments().contains(["-user-module-version", "1.0.0"]))

wat

[neonichu]

@swift-ci please smoke test

[neonichu]

@swift-ci please smoke test windows