skip export fails on Xcode 27 beta (Swift 6.4): "product 'SkipUnit-product' is linked as a static library by 'SkipAndroidBridge-product' and 'SkipBridge-product'"

[piercifani]

Environment

• Skip CLI 1.9.4 (Homebrew)
• skip 1.9.3, skip-bridge 0.17.2, skip-android-bridge 0.6.4, skip-lib 1.4.0, skip-unit 1.7.0
• Xcode 27 Beta 4 as the default Xcode instance
• Native/fused mode app (SKIP_BRIDGE bridging), multi-module package

Symptom

skip export fails during the Darwin verification build ("Build project foo") with:

error: Swift package product 'SkipLib-product' is linked as a static library by 'SkipAndroidBridge-product' and 'SkipBridge-product'. This will result in duplication of library code.
error: Swift package product 'SkipUnit-product' is linked as a static library by 'SkipAndroidBridge-product' and 'SkipBridge-product'. This will result in duplication of library code.

The failing command from the export log is /usr/bin/xcrun swift build --triple arm64-apple-ios --sdk .../iPhoneOS27.0.sdk, which resolves to the selected Xcode's toolchain.

Analysis

• SkipBridge and SkipAndroidBridge are unconditionally type: .dynamic; SkipLib/SkipUnit are automatic (static on Apple triples), so both get statically embedded into the two dynamic bridge products. This duplication has always existed — Swift ≤ 6.3 SwiftPM only warned about it, Swift 6.4's SwiftPM makes it a hard error, so every Skip user who selects Xcode 27 will hit this.
• skip-lib already has the fix behind an env gate (SKIP_BRIDGE != 0 → products become dynamic), but skip export does not set SKIP_BRIDGE when evaluating manifests for the darwin verification build, so the gate never engages. skip-unit has no such gate at all.

Suggested fix

Set SKIP_BRIDGE=1 (in bridging/native mode) for the manifest evaluation of skip export's darwin build, and/or add the same dynamic-product gate to skip-unit's Package.swift.

Workaround

DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer skip export ... (point xcrun back at a stable Xcode).