Apple Swift Package Manager - Swift 3.1.0 (swiftpm-12084)
Additional Detail from JIRA
SR-4072 Better response rather than "unsatisfiable"
Right now if your dependencies can't be satisfied, SwiftPM just gives you an "error: unsatisfiable". That message is way too terse and should at least clearly explain that dependency requirements can't be resolved. But beyond that, it should tell you which dependency can't be satisfied, and what the conflicting requirements are, and where they come from.