Switch to Scalafmt in build

* AvoidInfix in scalafmt.conf

* align.tokens in scalafmt.conf

* scalafmt in MultiJvm

* sbt-scalafmt 2.0.0-RC5

* scalafmt in all* command alias

* scalafmtAll in CONTRIBUTING.md

.scalafmt.conf

@@ -0,0 +1,48 @@
+version = 2.0.0-RC5
+
+style = defaultWithAlign
+
+danglingParentheses        = true
+docstrings                 = JavaDoc
+indentOperator             = spray
+maxColumn                  = 120
+rewrite.rules              = [RedundantParens, SortImports, AvoidInfix]
+unindentTopLevelOperators  = true
+align.tokens               = [{code = "=>", owner = "Case"}]
+align.openParenDefnSite    = true
+align.openParenCallSite    = true
+optIn.breakChainOnFirstMethodDot = false
+optIn.configStyleArguments = false
+danglingParentheses = false
+spaces.inImportCurlyBraces = true
+rewrite.neverInfix.excludeFilters = [
+  and
+  min
+  max
+  until
+  to
+  by
+  eq
+  ne
+  "should.*"
+  "contain.*"
+  "must.*"
+  in
+  ignore
+  be
+  taggedAs
+  thrownBy
+  synchronized
+  have
+  when
+  size
+  only
+  noneOf
+  oneElementOf
+  noElementsOf
+  atLeastOneElementOf
+  atMostOneElementOf
+  allElementsOf
+  inOrderElementsOf
+  theSameElementsAs
+]

CONTRIBUTING.md

@@ -147,6 +147,13 @@ project akka-cluster
 multi-jvm:testOnly akka.cluster.SunnyWeather
 ```
 
+To format the Scala source code:
+```
+sbt
+akka-cluster/scalafmtAll
+akka-persistence/scalafmtAll
+```
+
 ### Do not use `-optimize` Scala compiler flag
 
 Akka has not been compiled or tested with `-optimize` Scala compiler flag. (In sbt, you can specify compiler options in the `scalacOptions` key.)
@@ -360,7 +367,10 @@ In such situations we prefer 'internal' over 'impl' as a package name.
 
 ### Scala style 
 
-Akka uses [Scalariform](https://github.com/daniel-trinh/scalariform) to enforce some of the code style rules.
+Akka uses [Scalafmt](https://scalameta.org/scalafmt/docs/installation.html) to enforce some of the code style rules.
+
+When IntelliJ detects the `.scalafmt.conf` and promts "Scalafmt configuration detected in this project" you should
+select "Continue using IntelliJ formatter" and instead install the [Scalafmt IntelliJ plugin](https://scalameta.org/scalafmt/docs/installation.html#intellij). Install the nightly plugin (until version 2.0.0 or later becomes stable) and enable "Format on save".
 
 ### Java style
 

build.sbt

@@ -524,7 +524,6 @@ def akkaModule(name: String): Project =
   Project(id = name, base = file(name))
     .settings(akka.AkkaBuild.buildSettings)
     .settings(akka.AkkaBuild.defaultSettings)
-    .settings(akka.Formatting.formatSettings)
     .enablePlugins(BootstrapGenjavadoc)
 
 /* Command aliases one can run locally against a module
@@ -534,7 +533,8 @@ def akkaModule(name: String): Project =
 def commandValue(p: Project, externalTest: Option[Project] = None) = {
   val test = externalTest.getOrElse(p)
   val optionalMima = if (p.id.endsWith("-typed")) "" else s";${p.id}/mimaReportBinaryIssues"
-  s";${test.id}/test:compile$optionalMima;${docs.id}/paradox"
+  val optionalExternalTestFormat = externalTest.map(t => s";${t.id}/scalafmtAll").getOrElse("")
+  s";${p.id}/scalafmtAll$optionalExternalTestFormat;${test.id}/test:compile$optionalMima;${docs.id}/paradox"
 }
 addCommandAlias("allActor", commandValue(actor, Some(actorTests)))
 addCommandAlias("allRemote", commandValue(remote, Some(remoteTests)))

project/AkkaBuild.scala

@@ -9,6 +9,7 @@ import java.util.Properties
 
 import sbt.Keys._
 import sbt._
+import org.scalafmt.sbt.ScalafmtPlugin.autoImport._
 
 import scala.collection.breakOut
 
@@ -25,7 +26,6 @@ object AkkaBuild {
 
   lazy val rootSettings = Release.settings ++
     UnidocRoot.akkaSettings ++
-    Formatting.formatSettings ++
     Protobuf.settings ++ Seq(
       parallelExecution in GlobalScope := System.getProperty("akka.parallelExecution", parallelExecutionByDefault.toString).toBoolean,
       version in ThisBuild := "2.5-SNAPSHOT"

project/Formatting.scala

@@ -1,29 +0,0 @@
-/*
- * Copyright (C) 2016-2019 Lightbend Inc. <https://www.lightbend.com>
- */
-
-package akka
-
-import com.typesafe.sbt.SbtMultiJvm.MultiJvmKeys.MultiJvm
-import com.typesafe.sbt.SbtScalariform.ScalariformKeys
-import sbt._
-
-object Formatting {
-  import scalariform.formatter.preferences._
-
-  lazy val formatSettings = Seq(
-    ScalariformKeys.preferences := setPreferences(ScalariformKeys.preferences.value),
-    ScalariformKeys.preferences in Compile := setPreferences(ScalariformKeys.preferences.value),
-    ScalariformKeys.preferences in Test := setPreferences(ScalariformKeys.preferences.value),
-    ScalariformKeys.preferences in MultiJvm := setPreferences(ScalariformKeys.preferences.value)
-  )
-
-  def setPreferences(preferences: IFormattingPreferences) = preferences
-    .setPreference(RewriteArrowSymbols, true)
-    .setPreference(AlignParameters, true)
-    .setPreference(AlignSingleLineCaseStatements, true)
-    .setPreference(DoubleIndentConstructorArguments, false)
-    .setPreference(DoubleIndentMethodDeclaration, false)
-    .setPreference(DanglingCloseParenthesis, Preserve)
-    .setPreference(NewlineAtEndOfFile, true)
-}

project/MultiNode.scala

@@ -6,12 +6,12 @@ package akka
 
 import akka.TestExtras.Filter.Keys._
 import com.typesafe.sbt.MultiJvmPlugin.MultiJvmKeys.multiJvmCreateLogger
-import com.typesafe.sbt.{SbtMultiJvm, SbtScalariform}
+import com.typesafe.sbt.SbtMultiJvm
 import com.typesafe.sbt.SbtMultiJvm.MultiJvmKeys._
-import com.typesafe.sbt.SbtScalariform.ScalariformKeys
 import sbt.{ Def, _ }
 import sbt.Keys._
 import de.heikoseeberger.sbtheader.HeaderPlugin.autoImport._
+import org.scalafmt.sbt.ScalafmtPlugin.scalafmtConfigSettings
 
 object MultiNode extends AutoPlugin {
 
@@ -57,10 +57,9 @@ object MultiNode extends AutoPlugin {
 
   private val multiJvmSettings =
     SbtMultiJvm.multiJvmSettings ++
-      inConfig(MultiJvm)(SbtScalariform.configScalariformSettings) ++
+      inConfig(MultiJvm)(scalafmtConfigSettings) ++
       Seq(
         jvmOptions in MultiJvm := defaultMultiJvmOptions,
-        compileInputs in (MultiJvm, compile) := ((compileInputs in (MultiJvm, compile)) dependsOn (ScalariformKeys.format in MultiJvm)).value,
         scalacOptions in MultiJvm := (scalacOptions in Test).value,
         logLevel in multiJvmCreateLogger := Level.Debug, //  to see ssh establishment
         multiJvmCreateLogger in MultiJvm := { // to use normal sbt logging infra instead of custom sbt-multijvm-one

project/plugins.sbt

@@ -4,7 +4,7 @@ addSbtPlugin("com.typesafe.sbt" % "sbt-multi-jvm" % "0.4.0")
 //#sbt-multi-jvm
 
 addSbtPlugin("com.lightbend.sbt" % "sbt-java-formatter" % "0.4.1")
-addSbtPlugin("org.scalariform" % "sbt-scalariform" % "1.8.2")
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.0.0-RC5")
 addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.1")
 addSbtPlugin("com.typesafe.sbt" % "sbt-osgi" % "0.9.4")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.3.0")