Merge pull request #1360 from yadavan88/warning-rewrite

Fixed many compiler warnings after Scala 3.4 migration

Author: lor6

play-scala/dependency-injection/app/models/Order.scala

@@ -3,7 +3,8 @@ package models
 import play.api.libs.json.Json
 
 object Order {
-  implicit val writes = Json.writes[Order]
+  implicit val writes: play.api.libs.json.OWrites[models.Order] =
+    Json.writes[Order]
 }
 
 case class Order(id: Long, userId: Long, date: Long, isEnterprise: Boolean)

play-scala/dependency-injection/app/models/User.scala

@@ -5,5 +5,6 @@ import play.api.libs.json.Json
 case class User(id: Long, name: String)
 
 object User {
-  implicit val writes = Json.writes[User]
+  implicit val writes: play.api.libs.json.OWrites[models.User] =
+    Json.writes[User]
 }

play-scala/rest-api/app/controllers/TodoListController.scala

@@ -14,8 +14,11 @@ class TodoListController @Inject() (
   todoList += TodoListItem(1, "test", true)
   todoList += TodoListItem(2, "some other value", false)
 
-  implicit val todoListJson = Json.format[TodoListItem]
-  implicit val newTodoListJson = Json.format[NewTodoListItem]
+  implicit val todoListJson: play.api.libs.json.OFormat[models.TodoListItem] =
+    Json.format[TodoListItem]
+  implicit val newTodoListJson
+    : play.api.libs.json.OFormat[models.NewTodoListItem] =
+    Json.format[NewTodoListItem]
 
   // curl localhost:9000/todo
   def getAll(): Action[AnyContent] = Action {

scala-2-modules/scala2-core/README.md

@@ -8,4 +8,5 @@
 - [Introduction to Macros in Scala 2](https://www.baeldung.com/scala/scala2-macros)
 - [Demystifying View and Context Bounds](https://www.baeldung.com/scala/view-context-bounds)
 - [Introduction to Scala](https://www.baeldung.com/scala/scala-intro)
-- [Exception Handling in Scala](https://www.baeldung.com/scala/exception-handling)
+- [Exception Handling in Scala](https://www.baeldung.com/scala/exception-handling)
+- [Usages of Underscore (_) in Scala](https://www.baeldung.com/scala/underscore)

scala-core-modules/scala-core-2/src/main/scala/com/baeldung/scala/underscore/UnderscoreUsages.scala renamed to scala-2-modules/scala2-core/src/main/scala-2/com/baeldung/scala/underscore/UnderscoreUsages.scala

@@ -25,8 +25,8 @@ object ArbitraryArityUnionType extends App {
 
   sealed trait AOrB[A, B]
   object AOrB {
-    implicit def aInstance[A, B](a: A) = new AOrB[A, B] {}
-    implicit def bInstance[A, B](b: B) = new AOrB[A, B] {}
+    implicit def aInstance[A, B](a: A): AOrB[A, B] = new AOrB[A, B] {}
+    implicit def bInstance[A, B](b: B): AOrB[A, B] = new AOrB[A, B] {}
   }
 
   def isIntOrString[T <% String AOrB Int](t: T): String = t match {

scala-2-modules/scala2-core/src/main/scala-2/com/baeldung/scala/uniontypes/ArbitraryArityUnionType.scala

@@ -1,8 +1,9 @@
 package com.baeldung.scala.underscore
 
-import com.baeldung.scala.underscore.UnderscoreUsages._
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpec
+import UnderscoreUsages._
+
 class UnderscoreUsagesUnitTest extends AnyWordSpec with Matchers {
 
   "The underscore" should {
@@ -48,7 +49,7 @@ class UnderscoreUsagesUnitTest extends AnyWordSpec with Matchers {
       b shouldBe "b"
 
       text = "a,b,c,d,e"
-      val Array(a2, _*) = text.split(",")
+      val Array(a2, _*) = text.split(","): @unchecked
       a2 shouldBe "a"
 
       val Array(a3, b3, _, d, e) = text.split(",")

scala-core-modules/scala-core-2/src/test/scala/com/baeldung/scala/underscore/UnderscoreUsagesUnitTest.scala renamed to scala-2-modules/scala2-core/src/test/scala-2/com/baeldung/scala/underscore/UnderscoreUsagesUnitTest.scala

@@ -28,9 +28,10 @@ object GuavaCacheCustomMemoizationKeyConfig {
   val memoizedUnderlyingCustomKeyGuavaCache =
     CacheBuilder.newBuilder().maximumSize(10000L).build[String, Entry[User]]
 
-  implicit val customKeyCacheConfig = CacheConfig(memoization =
-    MemoizationConfig(toStringConverter = CustomKeyGenerator)
-  )
+  implicit val customKeyCacheConfig: scalacache.CacheConfig =
+    CacheConfig(memoization =
+      MemoizationConfig(toStringConverter = CustomKeyGenerator)
+    )
 
   implicit val guavaCache: Cache[User] = GuavaCache(
     memoizedUnderlyingCustomKeyGuavaCache

scala-2-modules/scala2-libraries/src/main/scala-2/com/baeldung/cache/service/SyncQueryCustomMemoizeKeyService.scala

@@ -18,12 +18,15 @@ object Protocol {
 }
 
 object impl {
-  implicit val localDateConvert = localDateConfigConvert(
-    DateTimeFormatter.ISO_DATE
-  )
-  implicit val localDateTimeConvert = localDateTimeConfigConvert(
-    DateTimeFormatter.ISO_DATE_TIME
-  )
+  implicit val localDateConvert: pureconfig.ConfigConvert[java.time.LocalDate] =
+    localDateConfigConvert(
+      DateTimeFormatter.ISO_DATE
+    )
+  implicit val localDateTimeConvert
+    : pureconfig.ConfigConvert[java.time.LocalDateTime] =
+    localDateTimeConfigConvert(
+      DateTimeFormatter.ISO_DATE_TIME
+    )
 }
 
 final case class Port(number: Int) extends AnyVal

scala-2-modules/scala2-libraries/src/main/scala-2/com/baeldung/scala/pureconfig/Configs.scala

@@ -138,9 +138,12 @@ class ShapelessUnitTest extends AnyWordSpec with Matchers {
     "calculate length of variant input types" in {
       import shapeless._
       object polyLength extends Poly1 {
-        implicit val listCase = at[List[Int]](i => i.length)
-        implicit val stringCase = at[String](d => d.length)
-        implicit val arrayCase = at[Array[Int]](d => d.length)
+        implicit val listCase: polyLength.Case.Aux[List[Int], Int] =
+          at[List[Int]](i => i.length)
+        implicit val stringCase: polyLength.Case.Aux[String, Int] =
+          at[String](d => d.length)
+        implicit val arrayCase: polyLength.Case.Aux[Array[Int], Int] =
+          at[Array[Int]](d => d.length)
       }
 
       val list = List(1, 2) :: "123" :: Array(1, 2, 3, 4) :: HNil

scala-2-modules/scala2-libraries/src/test/scala-2/com/baeldung/scala/shapeless/ShapelessUnitTest.scala

@@ -13,9 +13,11 @@ import scala.util._
 
 object MovieServer extends App {
 
-  implicit val system = ActorSystem("MoviesServer")
+  implicit val system: akka.actor.ActorSystem = ActorSystem("MoviesServer")
   val movieService = new MovieService()
-  implicit val movieFormat = jsonFormat3(Movie)
+  implicit val movieFormat
+    : spray.json.RootJsonFormat[com.baeldung.scala.akka.http.Movie] =
+    jsonFormat3(Movie)
 
   val route = path("movies" / "heartbeat") {
     get {

scala-akka-2/src/main/scala-2/com/baeldung/scala/akka/http/MovieServer.scala

@@ -10,7 +10,7 @@ class TestServiceUnitTest
   with BeforeAndAfterAll
   with Matchers {
   val testKit = ActorTestKit()
-  implicit val system = testKit.system
+  implicit val system: akka.actor.typed.ActorSystem[Nothing] = testKit.system
 
   // responsible for shutting down the ActorSystem
   override def afterAll(): Unit = testKit.shutdownTestKit()

scala-akka-3/src/test/scala/com/baeldung/scala/akka/TestServiceUnitTest.scala

@@ -110,7 +110,7 @@ class TrafficLightTestFutUnitTest extends TestServiceUnitTest {
   import scala.concurrent.duration._
   val sender = testKit.spawn(TrafficLight(), "traffic")
   val duration = 300.millis
-  implicit val timeout = Timeout(duration)
+  implicit val timeout: akka.util.Timeout = Timeout(duration)
 
   val signalFut =
     sender.ask(replyTo => TrafficLight.SignalCommand.GetSignal(replyTo))

scala-akka-3/src/test/scala/com/baeldung/scala/akka/UnitTest.scala

@@ -5,8 +5,8 @@ import akka.stream.ActorMaterializer
 
 object Configs {
 
-  implicit val actorSystem = ActorSystem("Alpakka")
-  implicit val materializer = ActorMaterializer()
+  implicit val actorSystem: akka.actor.ActorSystem = ActorSystem("Alpakka")
+  implicit val materializer: akka.stream.ActorMaterializer = ActorMaterializer()
 
   val filePath = "vehicle_data.log"
 

scala-akka/src/main/scala-2/com/baeldung/scala/akka/alpakka/Configs.scala

@@ -10,7 +10,7 @@ object ScalaCollections {
 
   val numbersListWithOperator: List[Int] = 1 :: 2 :: 3 :: 4 :: Nil
   val emptyListWithNil: List[Int] = Nil
-  val x :: xs = numbersList
+  val x :: xs = numbersList: @unchecked
 
   // Scala Set
   val emptySet: Set[Int] = Set()

scala-core-collections-modules/scala-core-collections-3/src/main/scala/com/baeldung/scala/commoncollections/ScalaCollections.scala

@@ -9,7 +9,6 @@ This module contains articles about Scala's core features.
 - [Futures and Promises in Scala](https://www.baeldung.com/scala/futures-promises)
 - [Named and Default Arguments in Scala](https://www.baeldung.com/scala/named-default-arguments)
 - [Self-Type Annotation in Scala](https://www.baeldung.com/scala/self-type-annotation)
-- [Usages of Underscore (_) in Scala](https://www.baeldung.com/scala/underscore)
 - [A DSL for Writing “20 seconds” in Scala](https://www.baeldung.com/scala/dsl-writing-20-seconds)
 - [Error Handling in Scala](https://www.baeldung.com/scala/error-handling)
 - [Higher-Kinded Types](https://www.baeldung.com/scala/higher-kinded-types)

scala-core-modules/scala-core-2/README.md

@@ -56,7 +56,7 @@ object ForComprehension {
     def foreach(f: A => Unit): Unit = f(result)
     def map[B](f: A => B): Result[B] = Result(f(result))
     def flatMap[B](f: A => Result[B]): Result[B] = f(result)
-    def withFilter(f: A => Boolean): Result[_] =
+    def withFilter(f: A => Boolean): Result[?] =
       if (f(result)) this else EmptyResult
   }
 

scala-core-modules/scala-core-2/src/main/scala/com/baeldung/scala/forcomprehension/ForComprehension.scala

@@ -3,12 +3,12 @@ package com.baeldung.scala.accessmodifiers
 import java.util.UUID.randomUUID
 
 abstract class Figure {
-  private[this] val code =
+  private val code =
     randomUUID.toString // accessible in the scope of the object-only
   def printCode: Unit = println(s"$code") // public access
 
   protected[accessmodifiers] val color: String // accessible in the scope of the package
-  protected[this] val lineWidth: Int // accessible for instances of this class and its subclasses instances
+  protected val lineWidth: Int // accessible for instances of this class and its subclasses instances
 
   protected val topPoint: Double // accessible in the scope of the class and subclasses
   protected val rightMostPoint: Double

scala-core-modules/scala-core-3/src/main/scala/com/baeldung/scala/accessmodifiers/Figure.scala

@@ -8,7 +8,7 @@ object NonStrictDataStructures {
   val stream = data.toStream
   // todo: check if this is ok, better to separate into separate module
   // val view: AnyRef with SeqView[Int, Seq[Int]] = data.view
-  val view: AnyRef with SeqView[Int] = data.view
+  val view: AnyRef & SeqView[Int] = data.view
 }
 
 case class Factorial() {

scala-core-modules/scala-core-3/src/main/scala/com/baeldung/scala/iteratorsvsstreamsvsviews/NonStrictDataStructures.scala

@@ -13,6 +13,6 @@ object TypeErasure {
 
   // Simply function that converts a variable number of values to a List of that type
   def convertValuesToList[T](values: T*): List[T] = {
-    List[T](values: _*)
+    List[T](values*)
   }
 }

scala-core-modules/scala-core-3/src/main/scala/com/baeldung/scala/typecasts/TypeErasure.scala

@@ -39,7 +39,7 @@ class TypeErasureUnitTest extends AnyWordSpec with Matchers {
     "work with varargs" in {
       def varargFn(str: String*) = str.length
       val input = Seq("Hello", "World")
-      assert(varargFn(input: _*) == 2)
+      assert(varargFn(input*) == 2)
     }
   }
 }

scala-core-modules/scala-core-3/src/test/scala/com/baeldung/scala/typecasts/TypeErasureUnitTest.scala

@@ -2,16 +2,16 @@ package com.baeldung.scala.adt
 
 object Examples {
   sealed trait Color
-  final case object White extends Color
-  final case object Black extends Color
+  case object White extends Color
+  case object Black extends Color
 
   sealed trait Name
-  final case object Pawn extends Name
-  final case object Rook extends Name
-  final case object Knight extends Name
-  final case object Bishop extends Name
-  final case object Queen extends Name
-  final case object King extends Name
+  case object Pawn extends Name
+  case object Rook extends Name
+  case object Knight extends Name
+  case object Bishop extends Name
+  case object Queen extends Name
+  case object King extends Name
 
   case class ChessPiece(color: Color, name: Name)
 
@@ -25,9 +25,9 @@ object Examples {
   }
 
   sealed trait SemaphoreColor
-  final case object Green extends SemaphoreColor
-  final case object Amber extends SemaphoreColor
-  final case object Red extends SemaphoreColor
+  case object Green extends SemaphoreColor
+  case object Amber extends SemaphoreColor
+  case object Red extends SemaphoreColor
 
   trait Feline
   trait Animal

scala-core-modules/scala-core-5/src/main/scala/com/baeldung/scala/adt/Examples.scala

@@ -35,8 +35,8 @@ object Functions {
   // getNameLengthDef.andThen(multiplyByTwoDef) //doesn't compile
 
   /** Method to Function value */
-  val getNameLengthDefFnValue = getNameLengthDef _
-  val multiplyByTwoDefFnValue = multiplyByTwoDef _
+  val getNameLengthDefFnValue = getNameLengthDef
+  val multiplyByTwoDefFnValue = multiplyByTwoDef
 
   getNameLengthDefFnValue.andThen(multiplyByTwoDefFnValue) // compiles
 

scala-core-modules/scala-core-6/src/main/scala/com/baeldung/scala/functions/Functions.scala

@@ -14,7 +14,7 @@ object ColorV2 {
 
 object Inference {
   def isError: Boolean = true
-  val consoleColor: Product with Serializable with Color =
+  val consoleColor: Product & Serializable & Color =
     if (isError) Color.Red else Color.Green
 
   val consoleColorV2: Color = if (isError) Color.Red else Color.Green

scala-core-modules/scala-core-7/src/main/scala/com/baeldung/scala/productserializable/ColorInference.scala

@@ -7,7 +7,7 @@ class CopyAnArrayToAnotherUnitTest extends AnyFlatSpec with Matchers {
   val array1 = Array(1, 2, 3, 4)
 
   "splat operator" should "copy an entire array to another" in {
-    var array2 = Array(array1: _*)
+    var array2 = Array(array1*)
     array1(1) should be(array2(1))
     array1 should not be (array2)
 

scala-core-modules/scala-core-7/src/test/scala/com/baeldung/scala/arrays/CopyAnArrayToAnotherUnitTest.scala

@@ -30,7 +30,7 @@ class InitializeAnArrayUnitTest extends AnyFlatSpec with Matchers {
 
   "splat operator" should "copy an entire list to an array" in {
     var list = List(1, 2, 3, 4)
-    var array = Array[Int](list: _*)
+    var array = Array[Int](list*)
 
     array(1) should be(list(1))
     array.length should be(4)

scala-core-modules/scala-core-7/src/test/scala/com/baeldung/scala/arrays/InitializeAnArrayUnitTest.scala

@@ -9,6 +9,6 @@ object NoParenthesis extends App {
   // greet "Alice"
 
   // But this works and it equivalent to greet("Alice")
-  this greet "Alice"
+  this `greet` "Alice"
 
 }

scala-core-modules/scala-core-8/src/main/scala/com/baeldung/scala/braces/NoParenthesis.scala

@@ -9,14 +9,14 @@ class ListReverserUnitTest extends AnyWordSpec with BeforeAndAfterEach {
 
   import ListReverser._
 
-  def testReverseSmallList(f: Seq[_] => Seq[_]): Assertion = {
+  def testReverseSmallList(f: Seq[?] => Seq[?]): Assertion = {
     val list = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     val expectedReversedList = List(10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
     val actualReversedList = f(list)
     assertResult(expectedReversedList)(actualReversedList)
   }
 
-  def testReverseBigList(f: Seq[_] => Seq[_]): Assertion = {
+  def testReverseBigList(f: Seq[?] => Seq[?]): Assertion = {
     val n = 100_000
     val vector: Vector[String] =
       (0 to n).foldLeft(Vector.empty[String])((v, _) =>
@@ -29,7 +29,7 @@ class ListReverserUnitTest extends AnyWordSpec with BeforeAndAfterEach {
   }
 
   "The naive list reverser" should {
-    val reversingFunction: Seq[_] => Seq[_] = naiveRecursiveReverse
+    val reversingFunction: Seq[?] => Seq[?] = naiveRecursiveReverse
 
     "reverse small lists" in {
       testReverseSmallList(reversingFunction)
@@ -41,7 +41,7 @@ class ListReverserUnitTest extends AnyWordSpec with BeforeAndAfterEach {
   }
 
   "The tail-recursive list reverser" should {
-    val reversingFunction: Seq[_] => Seq[_] = tailRecursiveReverse
+    val reversingFunction: Seq[?] => Seq[?] = tailRecursiveReverse
 
     "reverse small lists" in {
       testReverseSmallList(reversingFunction)
@@ -53,7 +53,7 @@ class ListReverserUnitTest extends AnyWordSpec with BeforeAndAfterEach {
   }
 
   "The folding list reverser" should {
-    val reversingFunction: Seq[_] => Seq[_] = foldBasedReverse
+    val reversingFunction: Seq[?] => Seq[?] = foldBasedReverse
 
     "reverse small lists" in {
       testReverseSmallList(reversingFunction)

scala-core-modules/scala-core-8/src/test/scala/com/baeldung/scala/reverselists/ListReverserUnitTest.scala

@@ -19,7 +19,7 @@ class ClassTUnitTest extends AnyFlatSpec with Matchers {
         )
 
       // Instantiate the class with arguments
-      Some(constructor.newInstance(args: _*).asInstanceOf[T])
+      Some(constructor.newInstance(args*).asInstanceOf[T])
     } catch {
       case e: Exception =>
         println(s"Error creating instance of ${clazz.getName}: ${e.getMessage}")
@@ -37,7 +37,7 @@ class ClassTUnitTest extends AnyFlatSpec with Matchers {
 
   "createInstance with .getClass" should "successfully create another instance of Person" in {
     val dummyPerson = new Person("Dummy")
-    val personClass: Class[_ <: Person] = dummyPerson.getClass
+    val personClass: Class[? <: Person] = dummyPerson.getClass
     val personInstance = createInstance(personClass, Array("Jane Doe": AnyRef))
 
     personInstance should not be empty
@@ -46,7 +46,7 @@ class ClassTUnitTest extends AnyFlatSpec with Matchers {
 
   "createInstance with .getClass" should "use the type of the variable to bound the type" in {
     val dummyPerson: Object = new Person("Dummy")
-    val personClass: Class[_ <: AnyRef] = dummyPerson.getClass
+    val personClass: Class[? <: AnyRef] = dummyPerson.getClass
     val personInstance = createInstance(personClass, Array("Jane Doe": AnyRef))
 
     personInstance should not be empty