add Scala 3 support

Author: mr-git

.github/workflows/ci.yml

@@ -11,6 +11,7 @@ jobs:
       matrix:
         scala:
           - 2.13.16
+          - 3.3.6
 
     steps:
       - uses: actions/checkout@v4
@@ -27,11 +28,15 @@ jobs:
       - name: setup SBT
         uses: sbt/setup-sbt@v1
 
+      - name: check code ${{ matrix.scala }}
+        run: sbt ++${{ matrix.scala }} clean check
+
       - name: build ${{ matrix.scala }}
-        run: sbt ++${{ matrix.scala }} clean check coverage test
+        run: sbt ++${{ matrix.scala }} clean coverage test
 
       - name: test coverage
         if: success()
+        run: sbt ++${{ matrix.scala }} coverageAggregate coveralls
         env:
-          COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
-        run: sbt ++${{ matrix.scala }} coverageReport coverageAggregate coveralls
+          COVERALLS_REPO_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          COVERALLS_FLAG_NAME: Scala ${{ matrix.scala }}

.github/workflows/release.yml

@@ -7,5 +7,5 @@ on:
 
 jobs:
   release:
-    uses: evolution-gaming/scala-github-actions/.github/workflows/release.yml@v3
+    uses: evolution-gaming/scala-github-actions/.github/workflows/release.yml@v4
     secrets: inherit

build.sbt

@@ -8,11 +8,31 @@ organizationHomepage := Some(url("https://evolution.com"))
 homepage := Some(url("https://github.com/evolution-gaming/sharding-strategy"))
 startYear := Some(2018)
 
-crossScalaVersions := Seq("2.13.16")
+crossScalaVersions := Seq("2.13.16", "3.3.6")
 scalaVersion := crossScalaVersions.value.head
 scalacOptions := Seq(
   "-release:17",
-  "-Xsource:3",
+  "-deprecation",
+)
+scalacOptions ++= crossSettings(
+  scalaVersion = scalaVersion.value,
+  // Good compiler options for Scala 2.13 are coming from com.evolution:sbt-scalac-opts-plugin:0.0.9,
+  // but its support for Scala 3 is limited, especially what concerns linting options.
+  if2 = Seq(
+    "-Xsource:3",
+  ),
+  // If Scala 3 is made the primary target, good linting scalac options for it should be added first.
+  if3 = Seq(
+    "-Ykind-projector:underscores",
+
+    // disable new brace-less syntax:
+    // https://alexn.org/blog/2022/10/24/scala-3-optional-braces/
+    "-no-indent",
+
+    // improve error messages:
+    "-explain",
+    "-explain-types",
+  ),
 )
 publishTo := Some(Resolver.evolutionReleases) // sbt-release
 versionPolicyIntention := Compatibility.BinaryCompatible // sbt-version-policy
@@ -31,7 +51,14 @@ libraryDependencies ++= Seq(
 
 licenses := Seq(("MIT", url("https://opensource.org/licenses/MIT")))
 
-//addCommandAlias("fmt", "scalafixAll; all scalafmtAll scalafmtSbt")
-//addCommandAlias("check", "scalafixEnable; scalafixAll --check; all versionPolicyCheck scalafmtCheckAll scalafmtSbtCheck")
-addCommandAlias("check", "versionPolicyCheck")
-addCommandAlias("build", "all compile test")
+//addCommandAlias("fmt", "all scalafmtAll scalafmtSbt")
+//addCommandAlias("check", "all versionPolicyCheck scalafmtCheckAll scalafmtSbtCheck")
+addCommandAlias("check", "+versionPolicyCheck")
+addCommandAlias("build", "+all compile test")
+
+def crossSettings[T](scalaVersion: String, if3: T, if2: T): T = {
+  scalaVersion match {
+    case version if version.startsWith("3") => if3
+    case _ => if2
+  }
+}

project/Dependencies.scala

@@ -1,10 +1,10 @@
-import sbt._
+import sbt.*
 
 object Dependencies {
 
   val scalatest     = "org.scalatest"       %% "scalatest"   % "3.2.19"
   val `cats-helper` = "com.evolutiongaming" %% "cats-helper" % "3.12.0"
-  val `ddata-tools` = "com.evolutiongaming" %% "ddata-tools" % "4.0.0"
+  val `ddata-tools` = "com.evolutiongaming" %% "ddata-tools" % "4.1.0"
 
   object Cats {
     private val version = "2.13.0"

src/main/scala/com/evolutiongaming/cluster/sharding/LoggingAllocationStrategy.scala

@@ -22,7 +22,7 @@ object LoggingAllocationStrategy {
       } mkString ", "
     }
 
-    def iterToStr(iter: Iterable[_]) = {
+    def iterToStr(iter: Iterable[?]) = {
       iter.toSeq.map { _.toString }.sorted.mkString("[", ",", "]")
     }
 

src/main/scala/com/evolutiongaming/cluster/sharding/ShardingStrategy.scala

@@ -226,7 +226,7 @@ object ShardingStrategy {
         } mkString ", "
       }
 
-      def iterToStr(iter: Iterable[_]) = {
+      def iterToStr(iter: Iterable[?]) = {
         iter.toSeq.map { _.toString }.sorted.mkString("[", ",", "]")
       }