Android: Swift 6.4 nightly test runner not executable on emulator (64-bit ELF) #137

Summary

On-device Android tests fail for the Swift 6.4.x development snapshot Android SDK with:

./SyndiKitTests-test-runner: not executable: 64-bit ELF file

Swift 6.3 Android legs (API 28 + 34) pass with android-run-tests: true. The same matrix with Swift 6.4 (6.4.x-DEVELOPMENT-SNAPSHOT-2026-06-15-a) fails when launching the test runner on the emulator.

Evidence

• Failing jobs on main @ f285c0c (post–v1.0.0 merge):
  https://github.com/brightdigit/SyndiKit/actions/runs/30008816075/job/89211429545
  https://github.com/brightdigit/SyndiKit/actions/runs/30008816075/job/89211429529
• Same 6.4-only failure pattern after #131 expanded Android to {6.3, 6.4} × {API 28, 34} and set android-run-tests: true.
• Before ci(android): cap API level at 34 and cover Swift 6.3 + 6.4-nightly #131, Android CI was build-only (android-run-tests: false) on a single 6.4 × API 34 leg and stayed green.

Suspected cause

Toolchain / SDK / emulator ABI mismatch for the Swift 6.4 Android nightly (aarch64 test binary vs emulator image), not a SyndiKit source regression. 6.3 on-device tests work with the same workflow action (brightdigit/swift-build → skiptools/swift-android-action).

Workaround

CI temporarily sets android-run-tests: false so the Android matrix stays build-only until this is fixed. Cross-compile coverage remains; on-device execution for 6.4 does not.

Follow-up

• Reproduce locally / isolate host vs guest arch for the 6.4 Android SDK test runner
• Check whether a newer 6.4 Android snapshot fixes the ELF/emulator mismatch
• Re-enable android-run-tests: true (at least for 6.4 rows, or the whole matrix) once green
• Optionally file/track upstream (Swift Android SDK / skiptools) if confirmed external