[BE2] switch to Scala 3

be2-scala/build.sbt

@@ -3,38 +3,19 @@ import sbtsonar.SonarPlugin.autoImport.sonarProperties
 
 name := "pop"
 
-scalaVersion := "2.13.7"
+scalaVersion := "3.1.2"
 
 // Recommended 2.13 Scala flags (https://nathankleyn.com/2019/05/13/recommended-scalac-flags-for-2-13) slightly adapted for PoP
 scalacOptions ++= Seq(
     "-deprecation", // Emit warning and location for usages of deprecated APIs.
-    "-explaintypes", // Explain type errors in more detail.
+    "-explain-types", // Explain type errors in more detail.
     "-feature", // Emit warning and location for usages of features that should be imported explicitly.
     "-language:existentials", // Existential types (besides wildcard types) can be written and inferred
     "-language:experimental.macros", // Allow macro definition (besides implementation and application)
     "-language:higherKinds", // Allow higher-kinded types
     "-language:implicitConversions", // Allow definition of implicit functions called views
     "-unchecked", // Enable additional warnings where generated code depends on assumptions.
-    "-Xcheckinit", // Wrap field accessors to throw an exception on uninitialized access.
     "-Xfatal-warnings", // Fail the compilation if there are any warnings.
-    "-Xlint:adapted-args", // Warn if an argument list is modified to match the receiver.
-    "-Xlint:constant", // Evaluation of a constant arithmetic expression results in an error.
-    "-Xlint:delayedinit-select", // Selecting member of DelayedInit.
-    "-Xlint:doc-detached", // A Scaladoc comment appears to be detached from its element.
-    "-Xlint:inaccessible", // Warn about inaccessible types in method signatures.
-    "-Xlint:infer-any", // Warn when a type argument is inferred to be `Any`.
-    "-Xlint:missing-interpolator", // A string literal appears to be missing an interpolator id.
-    "-Xlint:nullary-unit", // Warn when nullary methods return Unit.
-    "-Xlint:option-implicit", // Option.apply used implicit view.
-    "-Xlint:package-object-classes", // Class or object defined in package object.
-    "-Xlint:poly-implicit-overload", // Parameterized overloaded implicit methods are not visible as view bounds.
-    "-Xlint:private-shadow", // A private field (or class parameter) shadows a superclass field.
-    "-Xlint:stars-align", // Pattern sequence wildcard must align with sequence component.
-    "-Xlint:type-parameter-shadow", // A local type parameter shadows a type already in scope.
-    "-Ywarn-extra-implicit", // Warn when more than one implicit parameter section is defined.
-    "-Ywarn-numeric-widen", // Warn when numerics are widened.
-    "-Ycache-plugin-class-loader:last-modified", // Enables caching of classloaders for compiler plugins
-    "-Ycache-macro-class-loader:last-modified", // and macro definitions. This can lead to performance improvements.
 )
 
 // Reload changes automatically
@@ -100,9 +81,9 @@ sonarProperties := Map(
   "sonar.tests" -> "src/test/scala",
 
   "sonar.sourceEncoding" -> "UTF-8",
-  "sonar.scala.version" -> "2.13.7",
+  "sonar.scala.version" -> scalaVersion.value,
   // Paths to the test and coverage reports
-  "sonar.scala.coverage.reportPaths" -> "./target/scala-2.13/scoverage-report/scoverage.xml",
+  "sonar.scala.coverage.reportPaths" -> "./target/scala-3/scoverage-report/scoverage.xml",
 )
 
 assembly/ assemblyMergeStrategy := {
@@ -122,7 +103,7 @@ val AkkaHttpVersion = "10.2.9"
 
 libraryDependencies ++= Seq(
     "com.typesafe.akka" %% "akka-stream-typed" % AkkaVersion,   // Akka streams (Graph)
-    "com.typesafe.akka" %% "akka-http" % AkkaHttpVersion,       // Akka http (WebSockets)
+    ("com.typesafe.akka" %% "akka-http" % AkkaHttpVersion).cross(CrossVersion.for3Use2_13),       // Akka http (WebSockets)
     "com.typesafe.akka" %% "akka-cluster-tools" % AkkaVersion,  // Akka distributed publish/subscribe cluster
 
     "ch.qos.logback" % "logback-classic" % "1.1.3" % Runtime,   // Akka logging library

be2-scala/project/plugins.sbt

@@ -2,4 +2,3 @@ addSbtPlugin("org.scoverage" % "sbt-scoverage" % "1.6.1")
 addSbtPlugin("com.sonar-scala" % "sbt-sonar" % "2.3.0")
 addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "1.1.0")
 addSbtPlugin("com.rallyhealth.sbt" % "sbt-git-versioning" % "1.6.0")
-addSbtPlugin("ch.epfl.scala" % "sbt-scala3-migrate" % "0.5.1")