Add mill-mima to check binary compatibility (#117)

Author: lolgab

.github/workflows/actions.yml

@@ -16,6 +16,17 @@ jobs:
           java-version: 8
       - name: Run tests
         run: ./mill -i all __.publishArtifacts __.test
+  check-binary-compatibility:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 8
+      - name: Check Binary Compatibility
+        run: ./mill -i __.mimaReportBinaryIssues
 
   publish-sonatype:
     if: github.repository == 'com-lihaoyi/sourcecode' && contains(github.ref, 'refs/tags/')

build.sc

@@ -1,6 +1,8 @@
 import mill._, scalalib._, scalajslib._, scalanativelib._, publish._
 import $ivy.`de.tototec::de.tobiasroeser.mill.vcs.version_mill0.9:0.1.1`
 import de.tobiasroeser.mill.vcs.version.VcsVersion
+import $ivy.`com.github.lolgab::mill-mima_mill0.9:0.0.4`
+import com.github.lolgab.mill.mima._
 
 val dottyVersions = sys.props.get("dottyVersion").toList
 
@@ -18,11 +20,13 @@ val scalaNativeVersions = for {
   scalaNativeV <- Seq("0.4.0")
 } yield (scalaV, scalaNativeV)
 
-trait SourcecodeModule extends PublishModule {
+trait SourcecodeModule extends PublishModule with Mima {
   def artifactName = "sourcecode"
 
   def publishVersion = VcsVersion.vcsState().format()
 
+  def mimaPreviousVersions = VcsVersion.vcsState().lastTag.toSeq
+
   def pomSettings = PomSettings(
     description = artifactName(),
     organization = "com.lihaoyi",