From 9367595bdd518ecb6d7f049cb822c6190f43c011 Mon Sep 17 00:00:00 2001
From: Andriy Plokhotnyuk <plokhotnyuk@gmail.com>
Date: Mon, 13 Jan 2025 18:37:11 +0100
Subject: [PATCH] Add MiMa binary compatibility checks

---
 .github/workflows/ci.yml  | 20 ++++++++++++++-
 build.sbt                 |  5 +++-
 project/BuildHelper.scala | 52 ++++++++++++++++++++++++++++++---------
 3 files changed, 64 insertions(+), 13 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d57b98bd..12e1f0b2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -106,9 +106,27 @@ jobs:
       - name: Run tests
         run: sbt ++${{ matrix.scala }}! test${{ matrix.platform }}
 
+  mima_check:
+    runs-on: ubuntu-20.04
+    timeout-minutes: 30
+    steps:
+      - name: Checkout current branch
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 300
+      - name: Fetch tags
+        run: git fetch --depth=300 origin +refs/tags/*:refs/tags/*
+      - name: Setup Java (temurin@21)
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 21
+          cache: sbt
+      - run: sbt +mimaReportBinaryIssues
+
   ci:
     runs-on: ubuntu-20.04
-    needs: [lint, mdoc, benchmarks, test]
+    needs: [lint, mdoc, benchmarks, test, mima_check]
     steps:
       - name: Aggregate of lint, and all tests
         run: echo "ci passed"
diff --git a/build.sbt b/build.sbt
index 5b5bb35c..4f8d68d6 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,4 +1,5 @@
 import BuildHelper.*
+import com.typesafe.tools.mima.plugin.MimaKeys.mimaPreviousArtifacts
 import explicitdeps.ExplicitDepsPlugin.autoImport.moduleFilterRemoveValue
 import sbtcrossproject.CrossPlugin.autoImport.crossProject
 
@@ -60,7 +61,8 @@ val zioVersion = "2.1.14"
 lazy val zioJsonRoot = project
   .in(file("."))
   .settings(
-    publish / skip := true,
+    publish / skip        := true,
+    mimaPreviousArtifacts := Set(),
     unusedCompileDependenciesFilter -= moduleFilter("org.scala-js", "scalajs-library")
   )
   .aggregate(
@@ -400,6 +402,7 @@ lazy val docs = project
       zioJsonInteropScalaz7x.jvm,
       zioJsonGolden
     ),
+    mimaPreviousArtifacts := Set(),
     readmeAcknowledgement :=
       """|- Uses [JsonTestSuite](https://github.com/nst/JSONTestSuite) to test parsing. (c) 2016 Nicolas Seriot)
          |
diff --git a/project/BuildHelper.scala b/project/BuildHelper.scala
index bd5f1b29..946d1f73 100644
--- a/project/BuildHelper.scala
+++ b/project/BuildHelper.scala
@@ -1,3 +1,7 @@
+import com.typesafe.tools.mima.core.Problem
+import com.typesafe.tools.mima.core.ProblemFilters.exclude
+import com.typesafe.tools.mima.plugin.MimaKeys.{ mimaBinaryIssueFilters, mimaFailOnProblem, mimaPreviousArtifacts }
+import com.typesafe.tools.mima.plugin.MimaPlugin.autoImport.mimaCheckDirection
 import explicitdeps.ExplicitDepsPlugin.autoImport.*
 import org.portablescala.sbtplatformdeps.PlatformDepsPlugin.autoImport.*
 import sbt.*
@@ -5,6 +9,7 @@ import sbt.Keys.*
 import sbtbuildinfo.*
 import sbtbuildinfo.BuildInfoKeys.*
 import sbtcrossproject.CrossPlugin.autoImport.*
+import sbtdynver.DynVerPlugin.autoImport.previousStableVersion
 
 import scala.scalanative.sbtplugin.ScalaNativePlugin.autoImport.*
 
@@ -237,7 +242,28 @@ object BuildHelper {
     Test / parallelExecution := true,
     incOptions ~= (_.withLogRecompileOnMacro(false)),
     autoAPIMappings := true,
-    unusedCompileDependenciesFilter -= moduleFilter("org.scala-js", "scalajs-library")
+    unusedCompileDependenciesFilter -= moduleFilter("org.scala-js", "scalajs-library"),
+    mimaPreviousArtifacts := previousStableVersion.value.map(organization.value %% name.value % _).toSet,
+    mimaCheckDirection := {
+      def isPatch: Boolean = {
+        val Array(newMajor, newMinor, _) = version.value.split('.')
+        val Array(oldMajor, oldMinor, _) = previousStableVersion.value.getOrElse(version.value).split('.')
+        newMajor == oldMajor && newMinor == oldMinor
+      }
+
+      if (isPatch) "both"
+      else "backward"
+    },
+    mimaBinaryIssueFilters ++= Seq(
+      exclude[Problem]("zio.json.macros#package.<clinit>"),
+      exclude[Problem]("zio.JsonPackagePlatformSpecific.*"),
+      exclude[Problem]("zio.json.JsonDecoderPlatformSpecific.*"),
+      exclude[Problem]("zio.json.JsonEncoderPlatformSpecific.*"),
+      exclude[Problem]("zio.json.internal.*"),
+      exclude[Problem]("zio.json.package.*"),
+      exclude[Problem]("zio.json.yaml.internal.*")
+    ),
+    mimaFailOnProblem := true
   )
 
   def macroExpansionSettings = Seq(
@@ -258,14 +284,14 @@ object BuildHelper {
 
   def macroDefinitionSettings = Seq(
     scalacOptions += "-language:experimental.macros",
-    libraryDependencies ++= {
-      if (scalaVersion.value == ScalaDotty) Seq()
-      else
+    libraryDependencies ++= (CrossVersion.partialVersion(scalaVersion.value) match {
+      case Some((2, _)) =>
         Seq(
           "org.scala-lang" % "scala-reflect"  % scalaVersion.value % "provided",
           "org.scala-lang" % "scala-compiler" % scalaVersion.value % "provided"
         )
-    }
+      case _ => Seq()
+    })
   )
 
   val scalaJavaTimeVersion = "2.6.0"
@@ -290,12 +316,16 @@ object BuildHelper {
   )
 
   val scalaReflectTestSettings: List[Setting[_]] = List(
-    libraryDependencies ++= {
-      if (scalaVersion.value == ScalaDotty)
-        Seq("org.scala-lang" % "scala-reflect" % Scala213 % Test)
-      else
-        Seq("org.scala-lang" % "scala-reflect" % scalaVersion.value % Test)
-    }
+    libraryDependencies ++= (CrossVersion.partialVersion(scalaVersion.value) match {
+      case Some((2, _)) =>
+        Seq(
+          "org.scala-lang" % "scala-reflect" % scalaVersion.value % Test
+        )
+      case _ =>
+        Seq(
+          "org.scala-lang" % "scala-reflect" % Scala213 % Test
+        )
+    })
   )
 
   def welcomeMessage = onLoadMessage := {