WIP: Add cross-build for Scala 3.0

build.sbt

@@ -26,6 +26,30 @@ val jsr305Lib = "com.google.code.findbugs" % "jsr305" % "2.0.1"
 val scalacheckLib = "org.scalacheck" %% "scalacheck" % "1.15.4" % "test"
 val slf4jApi = "org.slf4j" % "slf4j-api" % slf4jVersion
 
+def scalatestLib(scalaBinaryVersion: String) =
+  if (isScala3(scalaBinaryVersion))
+    "org.scalatest" %% "scalatest" % "3.2.9" % "test"
+  else
+    "org.scalatest" %% "scalatest" % "3.1.2" % "test"
+
+def scalatestplusScalacheckLib(scalaBinaryVersion: String) =
+  if (isScala3(scalaBinaryVersion))
+    "org.scalatestplus" %% "scalacheck-1-15" % "3.2.9.0" % "test"
+  else
+    "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test"
+
+def scalatestplusJUnitLib(scalaBinaryVersion: String) =
+  if (isScala3(scalaBinaryVersion))
+    "org.scalatestplus" %% "junit-4-13" % "3.2.9.0" % "test"
+  else
+    "org.scalatestplus" %% "junit-4-12" % "3.1.2.0" % "test"
+
+def scalatestplusMockitoLib(scalaBinaryVersion: String) =
+  if (isScala3(scalaBinaryVersion))
+    "org.scalatestplus" %% "mockito-3-4" % "3.2.9.0" % "test"
+  else
+    "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test"
+
 def travisTestJavaOptions: Seq[String] = {
   // We have some custom configuration for the Travis environment
   // https://docs.travis-ci.com/user/environment-variables/#default-environment-variables
@@ -82,27 +106,31 @@ def jdk11GcJavaOptions: Seq[String] = {
 
 val defaultProjectSettings = Seq(
   scalaVersion := "2.13.6",
-  crossScalaVersions := Seq("2.12.12", "2.13.6")
+  crossScalaVersions := Seq("2.12.12", "2.13.6", "3.0.2-RC1") // TODO Scala3 use 3.0.2 once released
 )
 
+def isScala3(scalaBinaryVersion: String): Boolean =
+  scalaBinaryVersion == "3"
+
 val baseSettings = Seq(
   version := releaseVersion,
   organization := "com.twitter",
   // Workaround for a scaladoc bug which causes it to choke on empty classpaths.
   Compile / unmanagedClasspath += Attributed.blank(new java.io.File("doesnotexist")),
   libraryDependencies ++= Seq(
-    "org.scala-lang.modules" %% "scala-collection-compat" % "2.1.2",
+    "org.scala-lang.modules" %% "scala-collection-compat" % "2.4.4",
     // See https://www.scala-sbt.org/0.13/docs/Testing.html#JUnit
     "com.novocode" % "junit-interface" % "0.11" % "test",
-    "org.scalatest" %% "scalatest" % "3.1.2" % "test",
-    "org.scalatestplus" %% "junit-4-12" % "3.1.2.0" % "test"
+    scalatestLib(scalaBinaryVersion.value),
+    scalatestplusJUnitLib(scalaBinaryVersion.value),
   ),
   Test / fork := true, // We have to fork to get the JavaOptions
   // Workaround for cross building HealthyQueue.scala, which is not compatible between
   // 2.12- with 2.13+.
   Compile / unmanagedSourceDirectories += {
     val sourceDir = (Compile / sourceDirectory).value
     CrossVersion.partialVersion(scalaVersion.value) match {
+      case Some((3, _)) => sourceDir / "scala-2.13+"
       case Some((2, n)) if n >= 13 => sourceDir / "scala-2.13+"
       case _ => sourceDir / "scala-2.12-"
     }
@@ -120,7 +148,12 @@ val baseSettings = Seq(
     // Needs -missing-interpolator due to https://issues.scala-lang.org/browse/SI-8761
     "-Xlint:-missing-interpolator",
     "-Yrangepos"
-  ),
+  ) ++ Seq(
+    "-source:3.0-migration",
+    //"-rewrite",
+    "-explain",
+    "-explain-types",
+  ).filter(_ => isScala3(scalaBinaryVersion.value)),
   // Note: Use -Xlint rather than -Xlint:unchecked when TestThriftStructure
   // warnings are resolved
   javacOptions ++= Seq("-Xlint:unchecked", "-source", "1.8", "-target", "1.8"),
@@ -206,7 +239,7 @@ lazy val util = Project(
     utilJvm,
     utilLint,
     utilLogging,
-    utilMock,
+    //utilMock,  // TODO Scala3
     utilReflect,
     utilRegistry,
     utilRouting,
@@ -232,7 +265,7 @@ lazy val utilApp = Project(
     name := "util-app",
     libraryDependencies ++= Seq(
       "org.mockito" % "mockito-core" % mockitoVersion % "test",
-      "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test"
+      ("org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test").cross(CrossVersion.for3Use2_13)
     )
   ).dependsOn(utilAppLifecycle, utilCore, utilRegistry)
 
@@ -275,7 +308,7 @@ lazy val utilCache = Project(
       caffeineLib,
       jsr305Lib,
       "org.mockito" % "mockito-core" % mockitoVersion % "test",
-      "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test"
+      ("org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test").cross(CrossVersion.for3Use2_13)
     )
   ).dependsOn(utilCore)
 
@@ -318,13 +351,12 @@ lazy val utilCore = Project(
     // so that util-core would work better for Pants projects in IntelliJ.
     Compile / unmanagedSourceDirectories += baseDirectory.value / "concurrent-extra",
     libraryDependencies ++= Seq(
+      "org.scala-lang.modules" %% "scala-parser-combinators" % "2.0.0",
       caffeineLib % "test",
       scalacheckLib,
-      "org.scala-lang" % "scala-reflect" % scalaVersion.value,
-      "org.scala-lang.modules" %% "scala-parser-combinators" % "1.1.2",
       "org.mockito" % "mockito-core" % mockitoVersion % "test",
-      "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test",
-      "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test"
+      scalatestplusScalacheckLib(scalaBinaryVersion.value),
+      scalatestplusMockitoLib(scalaBinaryVersion.value),
     ),
     Compile / resourceGenerators += Def.task {
       val projectName = name.value
@@ -371,7 +403,10 @@ lazy val utilReflect = Project(
 ).settings(
     sharedSettings
   ).settings(
-    name := "util-reflect"
+    name := "util-reflect",
+    libraryDependencies ++= Seq(
+      "org.scala-lang" % "scala-reflect" % scalaVersion.value
+    )
   ).dependsOn(utilCore)
 
 lazy val utilHashing = Project(
@@ -384,7 +419,7 @@ lazy val utilHashing = Project(
     libraryDependencies ++= Seq(
       scalacheckLib,
       "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test"
-    )
+    ).map(_.cross(CrossVersion.for3Use2_13))
   ).dependsOn(utilCore % "test")
 
 lazy val utilJacksonAnnotations = Project(
@@ -427,7 +462,7 @@ lazy val utilJvm = Project(
     name := "util-jvm",
     libraryDependencies ++= Seq(
       "org.mockito" % "mockito-core" % mockitoVersion % "test",
-      "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test"
+      ("org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test").cross(CrossVersion.for3Use2_13)
     )
   ).dependsOn(utilApp, utilCore, utilStats)
 
@@ -460,7 +495,7 @@ lazy val utilMock = Project(
       // only depend on mockito-scala; it will pull in the correct corresponding version of mockito.
       "org.mockito" %% "mockito-scala" % mockitoScalaVersion,
       "org.mockito" %% "mockito-scala-scalatest" % mockitoScalaVersion % "test"
-    )
+    ).map(_.cross(CrossVersion.for3Use2_13))
   ).dependsOn(utilCore % "test")
 
 lazy val utilRegistry = Project(
@@ -472,7 +507,7 @@ lazy val utilRegistry = Project(
     name := "util-registry",
     libraryDependencies ++= Seq(
       "org.mockito" % "mockito-core" % mockitoVersion % "test",
-      "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test"
+      ("org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test").cross(CrossVersion.for3Use2_13)
     )
   ).dependsOn(utilCore)
 
@@ -494,10 +529,10 @@ lazy val utilSlf4jApi = Project(
     name := "util-slf4j-api",
     libraryDependencies ++= Seq(
       slf4jApi,
-      "org.mockito" %% "mockito-scala" % mockitoScalaVersion % "test",
+      "org.mockito" % "mockito-core" % mockitoVersion % "test",
       "org.slf4j" % "slf4j-simple" % slf4jVersion % "test"
     )
-  ).dependsOn(utilCore % "test", utilMock % "test")
+  ).dependsOn(utilCore % "test")
 
 lazy val utilSlf4jJulBridge = Project(
   id = "util-slf4j-jul-bridge",
@@ -519,7 +554,7 @@ lazy val utilSecurity = Project(
     libraryDependencies ++= Seq(
       scalacheckLib,
       "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test"
-    )
+    ).map(_.cross(CrossVersion.for3Use2_13))
   ).dependsOn(utilCore, utilLogging, utilSecurityTestCerts % "test")
 
 lazy val utilSecurityTestCerts = Project(
@@ -541,15 +576,18 @@ lazy val utilStats = Project(
     libraryDependencies ++= Seq(
       caffeineLib,
       jsr305Lib,
-      scalacheckLib,
       "com.fasterxml.jackson.core" % "jackson-core" % jacksonVersion,
       "com.fasterxml.jackson.core" % "jackson-databind" % jacksonVersion,
-      "com.fasterxml.jackson.module" %% "jackson-module-scala" % jacksonVersion exclude ("com.google.guava", "guava"),
       "org.mockito" % "mockito-core" % mockitoVersion % "test",
+    ) ++ Seq(
+      scalacheckLib,
+      "com.fasterxml.jackson.module" %% "jackson-module-scala" % jacksonVersion exclude ("com.google.guava", "guava"),
       "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test",
-      "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test"
-    ) ++ {
+      "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test",
+    ).map(_.cross(CrossVersion.for3Use2_13)) ++ {
       CrossVersion.partialVersion(scalaVersion.value) match {
+        case Some((3, major)) =>
+          Seq("org.scala-lang.modules" %% "scala-parallel-collections" % "1.0.3" % "test")
         case Some((2, major)) if major >= 13 =>
           Seq("org.scala-lang.modules" %% "scala-parallel-collections" % "0.2.0" % "test")
         case _ =>
@@ -567,9 +605,12 @@ lazy val utilTest = Project(
     name := "util-test",
     libraryDependencies ++= Seq(
       "org.mockito" % "mockito-all" % "1.10.19",
-      "org.scalatest" %% "scalatest" % "3.1.2",
-      "org.scalatestplus" %% "junit-4-12" % "3.1.2.0",
-      "org.scalatestplus" %% "mockito-1-10" % "3.1.0.0"
+      (if (isScala3(scalaBinaryVersion.value))
+        "org.scalatest" %% "scalatest" % "3.2.9"
+      else
+        "org.scalatest" %% "scalatest" % "3.1.2"),
+      ("org.scalatestplus" %% "junit-4-12" % "3.1.2.0").cross(CrossVersion.for3Use2_13),
+      ("org.scalatestplus" %% "mockito-1-10" % "3.1.0.0").cross(CrossVersion.for3Use2_13)
     )
   ).dependsOn(utilCore, utilLogging)
 
@@ -595,10 +636,13 @@ lazy val utilTunable = Project(
     sharedSettings
   ).settings(
     name := "util-tunable",
+    resolvers += // TODO Scala3 remove this once the library is published properly
+      "Sonatype OSS Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots",
     libraryDependencies ++= Seq(
       "com.fasterxml.jackson.core" % "jackson-core" % jacksonVersion,
       "com.fasterxml.jackson.core" % "jackson-databind" % jacksonVersion,
-      "com.fasterxml.jackson.module" %% "jackson-module-scala" % jacksonVersion exclude ("com.google.guava", "guava")
+      //("com.fasterxml.jackson.module" %% "jackson-module-scala" % jacksonVersion exclude ("com.google.guava", "guava")).cross(CrossVersion.for3Use2_13)
+      "com.fasterxml.jackson.module" %% "jackson-module-scala" % "2.13.0-SNAPSHOT", // TODO Scala3 global jackson upgrade first?
     )
   ).dependsOn(utilApp, utilCore)
 
@@ -611,15 +655,16 @@ lazy val utilValidator = Project(
     name := "util-validator",
     libraryDependencies ++= Seq(
       caffeineLib,
-      scalacheckLib,
       "jakarta.validation" % "jakarta.validation-api" % "3.0.0",
       "org.hibernate.validator" % "hibernate-validator" % "7.0.1.Final",
       "org.glassfish" % "jakarta.el" % "4.0.0",
-      "org.json4s" %% "json4s-core" % "3.6.7",
       "com.fasterxml.jackson.core" % "jackson-annotations" % jacksonVersion % "test",
-      "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test",
       "org.slf4j" % "slf4j-simple" % slf4jVersion % "test"
-    )
+    ) ++ Seq(
+      "org.json4s" %% "json4s-core" % "3.6.7",
+      scalacheckLib,
+      "org.scalatestplus" %% "scalacheck-1-14" % "3.1.2.0" % "test",
+    ).map(_.cross(CrossVersion.for3Use2_13))
   ).dependsOn(utilCore, utilReflect, utilSlf4jApi)
 
 lazy val utilZk = Project(
@@ -632,7 +677,7 @@ lazy val utilZk = Project(
     libraryDependencies ++= Seq(
       zkDependency,
       "org.mockito" % "mockito-core" % mockitoVersion % "test",
-      "org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test"
+      ("org.scalatestplus" %% "mockito-3-3" % "3.1.2.0" % "test").cross(CrossVersion.for3Use2_13)
     )
   ).dependsOn(utilCore, utilLogging)
 

project/plugins.sbt

@@ -2,5 +2,5 @@ resolvers += Classpaths.sbtPluginReleases
 resolvers += Resolver.sonatypeRepo("snapshots")
 
 addSbtPlugin("com.typesafe.sbt" % "sbt-site" % "1.3.0")
-addSbtPlugin("org.scoverage" % "sbt-scoverage" % "1.6.1")
+addSbtPlugin("org.scoverage" % "sbt-scoverage" % "1.8.2")
 addSbtPlugin("pl.project13.scala" % "sbt-jmh" % "0.4.0")

util-app/src/main/scala/com/twitter/app/ClassPath.scala

@@ -71,7 +71,7 @@ private[app] sealed abstract class ClassPath[CpInfo <: ClassPath.Info] {
   // TODO - add suppport for the ModulePath after dropping JDK 8 support.
   private[this] def urlsFromClasspath(): Array[URL] = {
     val classpath: String = System.getProperty("java.class.path")
-    classpath.split(File.pathSeparator).map { pathEntry: String =>
+    classpath.split(File.pathSeparator).map { (pathEntry: String) =>
       Paths.get(pathEntry).toAbsolutePath().toUri().toURL
     }
   }

util-app/src/main/scala/com/twitter/app/Flaggable.scala

@@ -132,19 +132,19 @@ object Flaggable {
 
   implicit val ofInt: Flaggable[Int] = mandatory(_.toInt)
   implicit val ofJavaInteger: Flaggable[JInteger] =
-    mandatory { s: String => JInteger.valueOf(s.toInt) }
+    mandatory { (s: String) => JInteger.valueOf(s.toInt) }
 
   implicit val ofLong: Flaggable[Long] = mandatory(_.toLong)
   implicit val ofJavaLong: Flaggable[JLong] =
-    mandatory { s: String => JLong.valueOf(s.toLong) }
+    mandatory { (s: String) => JLong.valueOf(s.toLong) }
 
   implicit val ofFloat: Flaggable[Float] = mandatory(_.toFloat)
   implicit val ofJavaFloat: Flaggable[JFloat] =
-    mandatory { s: String => JFloat.valueOf(s.toFloat) }
+    mandatory { (s: String) => JFloat.valueOf(s.toFloat) }
 
   implicit val ofDouble: Flaggable[Double] = mandatory(_.toDouble)
   implicit val ofJavaDouble: Flaggable[JDouble] =
-    mandatory { s: String => JDouble.valueOf(s.toDouble) }
+    mandatory { (s: String) => JDouble.valueOf(s.toDouble) }
 
   // Conversions for common non-primitive types and collections.
   implicit val ofDuration: Flaggable[Duration] = mandatory(Duration.parse(_))

util-app/src/main/scala/com/twitter/app/Flags.scala

@@ -4,6 +4,7 @@ import scala.collection.immutable.TreeSet
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 import scala.jdk.CollectionConverters._
+import scala.reflect.ClassTag
 import scala.util.control.NonFatal
 
 /**
@@ -277,8 +278,9 @@ class Flags(argv0: String, includeGlobal: Boolean, failFastUntilParsed: Boolean)
    * @param name The name of the flag.
    * @param help The help string of the flag.
    */
-  def apply[T](name: String, help: String)(implicit _f: Flaggable[T], m: Manifest[T]): Flag[T] = {
-    val f = new Flag[T](name, help, m.toString, failFastUntilParsed)
+  def apply[T](name: String, help: String)(implicit _f: Flaggable[T], m: ClassTag[T]): Flag[T] = {
+    // TODO Scala3 Is ClassTag ok? Should we capitalize the type name?
+    val f = new Flag[T](name, help, m.runtimeClass.getTypeName.capitalize, failFastUntilParsed)
     add(f)
     f
   }

util-app/src/main/scala/com/twitter/app/GlobalFlag.scala

@@ -1,6 +1,7 @@
 package com.twitter.app
 
 import java.lang.reflect.Modifier
+import scala.reflect.ClassTag
 import scala.util.control.NonFatal
 
 /**
@@ -85,8 +86,9 @@ abstract class GlobalFlag[T] private[app] (
    *
    * @param help documentation regarding usage of this [[Flag]].
    */
-  def this(help: String)(implicit _f: Flaggable[T], m: Manifest[T]) =
-    this(Right(m.toString), help)
+  def this(help: String)(implicit _f: Flaggable[T], m: ClassTag[T]) =
+    // TODO Scala3 Is ClassTag ok? Should we capitalize the type name?
+    this(Right(m.runtimeClass.getTypeName.capitalize), help)
 
   /**
    * The "name", or "id", of this [[Flag]].

util-app/src/test/scala/com/twitter/app/AppTest.scala

@@ -205,7 +205,7 @@ class AppTest extends AnyFunSuite {
     assert(n2 == 0)
     assert(!f.isDefined)
 
-    p.setDone
+    p.setDone()
     assert(n2 == 1)
     assert(f.isDefined)
   }

util-cache-guava/src/main/scala/com/twitter/cache/guava/GuavaCache.scala

@@ -53,7 +53,7 @@ object GuavaCache {
    */
   def fromLoadingCache[K, V](cache: LoadingCache[K, Future[V]]): K => Future[V] = {
     val evicting = EvictingCache.lazily(new LoadingFutureCache(cache));
-    { key: K => evicting.get(key).get.interruptible() }
+    { (key: K) => evicting.get(key).get.interruptible() }
   }
 
   /**

util-cache/src/main/scala/com/twitter/cache/ConcurrentMapCache.scala

@@ -20,7 +20,7 @@ class ConcurrentMapCache[K, V](underlying: ConcurrentMap[K, Future[V]]) extends
   def set(key: K, value: Future[V]): Unit = underlying.put(key, value)
 
   def getOrElseUpdate(key: K)(compute: => Future[V]): Future[V] = {
-    val p = Promise[V]
+    val p = Promise[V]()
     underlying.putIfAbsent(key, p) match {
       case null =>
         p.become(compute)

util-cache/src/main/scala/com/twitter/cache/FutureCache.scala

@@ -107,7 +107,7 @@ object FutureCache {
    * @see [[standard]] for the equivalent Java API.
    */
   def default[K, V](fn: K => Future[V], cache: FutureCache[K, V]): K => Future[V] =
-    AsyncMemoize(fn, new EvictingCache(cache)) andThen { f: Future[V] => f.interruptible() }
+    AsyncMemoize(fn, new EvictingCache(cache)) andThen { (f: Future[V]) => f.interruptible() }
 
   /**
    * Alias for [[default]] which can be called from Java.