Handle Swift 6.2 SPM build layout when compiling Dangerfile

[Copilot]

Swift 6.2 (Xcode 27) changed SwiftPM build outputs from .build/debug[/Modules] to .build/out/Products/Debug, which caused Dangerfile compilation to fail with no such module 'Danger'. This update makes path resolution layout-aware while preserving legacy behavior.

• Build artifact path resolution

  • SPMDanger now detects build layout and resolves buildFolder to:
    • modern: .build/out/Products/Debug (when present)
    • legacy fallback: .build/debug
  • moduleFolder now aligns with the resolved layout:
    • modern layout uses the same folder directly
    • legacy layout retains .../Modules behavior for newer compilers

• Targeted test coverage

  • Added/updated RunnerLib tests to cover:
    • modern build folder selection
    • modern module folder selection
    • legacy fallback behavior

public var buildFolder: String {
    switch buildLayout {
    case .modern: return modernBuildFolder      // .build/out/Products/Debug
    case .legacy: return legacyBuildFolder      // .build/debug
    }
}

[f-meloni]

@copilot update the CHANGELOG

[Copilot]

@copilot update the CHANGELOG

Updated in commit 038d640 by adding a Master entry to /home/runner/work/swift/swift/CHANGELOG.md for the Swift 6.2/Xcode 27 SwiftPM build layout fix.

[renfrenkel]

Hi @f-meloni, any update on this?

[f-meloni]

@copilot CI is failing

[Copilot]

@copilot CI is failing

Fixed in commit eda5cdd. I investigated the failing CI run logs and pinned Node to ${{ env.DANGER_JS_NODE_VERSION }} (20.x) for all macOS jobs that run danger-js in /home/runner/work/swift/swift/.github/workflows/ci.yml, which addresses the Node 24 incompatibility error.

[github-actions]

	Warnings
⚠️	Sources/RunnerLib/SPMDanger.swift#L71 - Opening braces should be preceded by a single space and on the same line as the declaration (opening_brace)
⚠️	Sources/RunnerLib/SPMDanger.swift#L93 - Opening braces should be preceded by a single space and on the same line as the declaration (opening_brace)
⚠️	Tests/RunnerLibTests/SPMDangerTests.swift#L91 - Line should be 140 characters or less; currently it has 149 characters (line_length)

Generated by 🚫 Danger Swift against eda5cdd

[renfrenkel]

@copilot CI is still failing

[renfrenkel]

@f-meloni CI is still failing :(

[DylanBettermannDD]

Hi @f-meloni — I hit this same bug and want to share a reproduction plus a possible amendment to this PR's approach, since it looks like the CI issue is the only thing blocking it.

A regression in this PR's approach

This PR moves buildFolder to a hardcoded .build/out/Products/Debug when that directory exists, keeping the #if compiler(<6.0) check otherwise. That's correct for a clean build, but it regresses on a toolchain switch without a swift package clean — exactly the scenario a CI cache restore across Xcode versions triggers:

1. Build under a toolchain that defaults to swiftbuild → .build/out/Products/Debug is created, .build/debug symlinks to it.
2. Build again under an older toolchain (native build system), without cleaning → SwiftPM correctly repoints .build/debug → arm64-apple-macosx/debug, but .build/out/Products/Debug survives on disk with stale modules from the first build.
3. This PR's directory-existence check sees the stale out/Products/Debug and selects it:

   error: module compiled with Swift 6.4 cannot be imported by the Swift 6.3.3 compiler
   

4. Reading through the repointed .build/debug symlink instead succeeds — SwiftPM already did the work of tracking which output is current, so following its symlink is more robust than hardcoding a specific layout path.

I verified this locally in both directions (swiftbuild→native and native→swiftbuild, each without a clean) — .build/debug itself stays a valid, correctly-repointed symlink under every layout; only the module search path underneath it needs to change.

Suggested amendment

Leave buildFolder untouched (it's already correct), and instead of a directory-existence check, probe for the exact Danger.swiftmodule artifact at both candidate locations under buildFolder, falling back to today's #if compiler(<6.0) default when the probe is ambiguous (both or neither exist — e.g. a stale, empty, or partial Modules/):

public var moduleFolder: String {
    let flatModule = buildFolder + "/Danger.swiftmodule"
    let nestedModule = buildFolder + "/Modules/Danger.swiftmodule"

    switch (fileManager.fileExists(atPath: flatModule), fileManager.fileExists(atPath: nestedModule)) {
    case (true, false):
        return buildFolder
    case (false, true):
        return buildFolder + "/Modules"
    default:
        #if compiler(<6.0)
            return buildFolder
        #else
            return buildFolder + "/Modules"
        #endif
    }
}

This keeps every currently-working configuration byte-identical (both unambiguous branches match today's two #if compiler outcomes exactly) while fixing the cases that are broken today, and it self-heals through any toolchain switch since it always reads through the live .build/debug symlink rather than a hardcoded path.

I've written this up as a full PR with tests (including coverage for the empty/partial-Modules/ case, and the equivalent fix for Script.artifactsPath's identical pattern) at #663, in case it's useful — happy to have it superseded by an amendment here instead if that's easier to land given the CI history on this thread.