Invalid build setting `swiftLanguageVersion`

[glbrntt]

Is it reproducible with SwiftPM command-line tools: swift build, swift test, swift package etc?

• Confirmed reproduction steps with SwiftPM CLI. The description text must include reproduction steps with either of command-line SwiftPM commands, swift build, swift test, swift package etc.

Description

Swift 6 nightly builds using swiftLanguageVersion now fail with:

InternalError(description: "Internal error. Please file a bug at https://github.com/swiftlang/swift-package-manager/issues with this info. invalid build setting swiftLanguageVersion"

This makes sense as it's now been renamed to swiftLanguageMode (#7620).

Expected behavior

Build should still compile but warn about the deprecated setting.

Presumably this code should return a setting with name "swiftLanguageMode" rather than "swiftLanguageVersion".

Actual behavior

Build fails with an error

InternalError(description: "Internal error. Please file a bug at https://github.com/swiftlang/swift-package-manager/issues with this info. invalid build setting swiftLanguageVersion"

Steps to reproduce

No response

Swift Package Manager version/commit hash

No response

Swift & OS version (output of swift --version ; uname -a)

No response

[MaxDesiatov]

@glbrntt can you provide a sample package the reproduces the issue? Thanks!

[glbrntt]

Repro.zip

This was on swiftlang/swift:nightly-6.0-jammy at sha256:4624a3c7404f479e55d69dc5e41f94e399cb0c11f291f81689d81e593b409610

[MaxDesiatov]

This setting was introduced in a 6.0 development snapshot and was never included in a release tag. I don't think that subsequent 6.0 snapshots are committed to compatibility with previous 6.0 snapshots.

@dempseyatgithub @bnbarham @xedin WDYT?

[glbrntt]

I think that's fine, but in the PR the setting was deprecated, which makes sense as it gives early adopters a way to find out what to use next.

However it still causes builds to fail because the old (deprecated) setting is now invalid so we lose the 'gracefulness' of deprecating the setting. There's also a mismatch between nightly-6.0, nightly-main, and released toolchains for macOS which means its hard for libraries to develop for both platforms (at the moment).

[MaxDesiatov]

I don't think that gracefulness can and should be guaranteed in development snapshots. The mismatch will disappear as soon the change is propagated to different builds.

[xedin]

I think, this is just a bug, deprecated swiftLangaugeVersion should produce a swiftLanguageMode setting. This is something we missed during review, I'll fix it.

[dempseyatgithub]

I think, this is just a bug, deprecated swiftLangaugeVersion should produce a swiftLanguageMode setting. This is something we missed during review, I'll fix it.

Thank you @xedin.