Dangerfile compilation fails with Swift 6.2 (Xcode 27) due to SPM build path changes #661

Summary

Danger Swift 3.20.2 fails to compile the Dangerfile when using Swift 6.2 (bundled with Xcode 27) because SPM's build output layout has changed.

Error

_tmp_dangerfile.swift:1:8: error: no such module 'Danger'
 1 | import Danger
   |        `- error: no such module 'Danger'
 2 | import DangerIntegration
 3 | import Foundation

Followed by:

ERROR: Dangerfile eval failed at Dangerfile.swift
ERROR: Could not get the results JSON file at /var/folders/.../danger-response.json

Cause

The runner invokes swiftc with hardcoded legacy paths:

swift --driver-mode=swift \
  -L .../Packages/DangerIntegration/.build/debug \
  -I .../Packages/DangerIntegration/.build/debug/Modules \
  -lDangerDeps \
  _tmp_dangerfile.swift ...

Swift 6.2 (Xcode 27) changed the SPM build output layout. Modules now go to .build/out/Products/Debug/ instead of .build/debug/Modules/, so the -I and -L flags point to directories that no longer contain the built modules/libraries.

Environment

• Xcode 27 (Swift 6.2)
• Danger Swift 3.20.2
• macOS 26+
• danger-js invoking danger-swift via --process

Steps to Reproduce

1. Install Xcode 27 and set it as the active toolchain
2. Build DangerIntegration package with swift build
3. Run danger ci — the Dangerfile compilation fails because the runner looks for modules at .build/debug/Modules/ which no longer exists

Suggested Fix

Update the module/library search paths in the runner (where it constructs the -I and -L flags) to use the new SPM layout (.build/out/Products/Debug/) when building with Swift 6.2+, and fall back to the legacy path for older Swift versions.