とりあえずswift-4.2-DEVELOPMENT-SNAPSHOT-2018-06-11-aだと

$ docker run --privileged -it -v `pwd`:`pwd` -w `pwd` --rm norionomura/swift:swift-4.2-branch swift test Compile Swift Module 'SwiftyMath' (70 sources) /Users/norio/github/SwiftyMath/Sources/SwiftyMath/Matrix/SquareMatrix.swift:18:1: error: conditional conformance of type '_Matrix<n, m, R>' to protocol 'Ring' does not imply conformance to inherited protocol 'Monoid' extension SquareMatrix: Ring where n == m { ^ /Users/norio/github/SwiftyMath/Sources/SwiftyMath/Matrix/SquareMatrix.swift:18:1: note: did you mean to explicitly state the conformance like 'extension _Matrix: Monoid where ...'? extension SquareMatrix: Ring where n == m { ^ error: terminated(1): /usr/bin/swift-build-tool -f /Users/norio/github/SwiftyMath/.build/debug.yaml test output:

になります。 (edited)