Linux (Ubuntu Mate 16.04LTS) on RaspberryPi2 (armv7).
Additional Detail from JIRA
Bug, Linux, Swift4, arm, armv7
Compiling the latest sources from swift-4.0-branch I'm seeing multiple test failures, among those Runtime/weak-reference-racetests.swift (that makes SPM build fail) and a good amount of tests in *stdlib/ErrorHandling.swift (issues with throw and try!)*._
Despite the name, the weak-reference-racetests issue does not seem to be related to race conditions as the name would imply. I'm opening a separate issue (SR-5846) for that since it's what I'm investigating right now.
I'm attaching the full output, but to recap what is failing: