support new scala 3 syntax

.github/workflows/test.yml

@@ -10,10 +10,14 @@ jobs:
     strategy:
       matrix:
         scala: [2_12, 2_13, 3]
-        script: [mima, e2e, proptest]
+        script: [mima, e2e, test]
         include:
         - scala: 2_12
           script: examples_and_formatting
+        - scala: 2_13
+          script: scala3_compat_test
+        - scala: 3
+          script: scala3_compat_test
 
     steps:
     - uses: actions/checkout@v3

.scalafmt.conf

@@ -9,3 +9,9 @@ project.excludeFilters = [
    "scalapb-runtime/.*/scala.*/com/google/protobuf/.*",
    "scalapb-runtime/.*/scala.*/scalapb/options/.*"
 ]
+
+fileOverride {
+   "glob:**/src/main/scala-3/**" {
+      runner.dialect = scala3
+   }
+}

CHANGELOG.md

@@ -3,6 +3,8 @@
 ## [0.11.14]
 - Repeated extensions can now use arbitrary iterable types or any collection type there is a
   CollectionAdapter for (#1509)
+- Introduced new generator parameter scala3_sources (also available via
+  scalapb.proto) to generate sources that are compatible with Scala 3 (#1576)
 
 ## [0.11.13]
 - Added input and output message type for method descriptor (#1503)

build.sbt

@@ -150,7 +150,12 @@ lazy val compilerPlugin = (projectMatrix in file("compiler-plugin"))
     ),
     mimaPreviousArtifacts := Set("com.thesamet.scalapb" %% "compilerplugin" % MimaPreviousVersion),
     mimaBinaryIssueFilters := Seq(
-      ProblemFilters.exclude[ReversedMissingMethodProblem]("scalapb.options.*")
+      ProblemFilters.exclude[ReversedMissingMethodProblem]("scalapb.options.*"),
+      ProblemFilters.exclude[DirectMissingMethodProblem]("scalapb.compiler.GeneratorParams.*"),
+      ProblemFilters.exclude[DirectMissingMethodProblem]("scalapb.gen.*"),
+      ProblemFilters.exclude[DirectMissingMethodProblem](
+        "scalapb.compiler.ProtobufGenerator.generateMessageCompanionMatcher"
+      )
     ),
     PB.protocVersion := protobufCompilerVersion,
     Compile / PB.targets := Seq(
@@ -218,10 +223,24 @@ lazy val protocGenScalaNativeImage =
       Compile / mainClass := Some("scalapb.ScalaPbCodeGenerator")
     )
 
+lazy val ScalaSources  = GeneratorAxis("", "scalagen")
+lazy val Scala3Sources = GeneratorAxis("Scala3Sources", "scala3sources")
+
 lazy val proptest = (projectMatrix in file("proptest"))
-  .defaultAxes()
   .dependsOn(compilerPlugin % "compile->compile;test->test", runtime, grpcRuntime)
-  .jvmPlatform(scalaVersions = Seq(Scala212, Scala213, Scala3))
+  .defaultAxes()
+  .customRow(
+    scalaVersions = Seq(Scala212, Scala213, Scala3),
+    axisValues = Seq(ScalaSources, VirtualAxis.jvm),
+    settings = Seq()
+  )
+  .customRow(
+    scalaVersions = Seq(Scala213, Scala3),
+    axisValues = Seq(Scala3Sources, VirtualAxis.jvm),
+    settings = Seq(
+      Test / javaOptions += "-Dscala3_sources"
+    )
+  )
   .settings(commonSettings)
   .settings(
     publishArtifact := false,
@@ -370,13 +389,41 @@ lazy val e2e = (projectMatrix in file("e2e"))
                                                                                        )
                                                                                          "scalajvm-3"
                                                                                        else
-                                                                                         "scalajvm-2")
+                                                                                         "scalajvm-2"),
+      Compile / PB.targets := Seq(
+        genModule("scalapb.ScalaPbCodeGenerator$") -> (Compile / sourceManaged).value
+      )
+    )
+  )
+  .customRow(
+    scalaVersions = Seq(Scala213, Scala3),
+    axisValues = Seq(Scala3Sources, VirtualAxis.jvm),
+    settings = Seq(
+      Test / unmanagedSourceDirectories += (Test / scalaSource).value.getParentFile / (if (
+                                                                                         isScala3.value
+                                                                                       )
+                                                                                         "scalajvm-3"
+                                                                                       else
+                                                                                         "scalajvm-2"),
+      scalacOptions ++=
+        (if (isScala3.value) Seq("-source", "future") else Seq("-Xsource:3")),
+      Test / scalacOptions --=
+        (if (isScala3.value) Seq("-source", "future") else Seq("-Xsource:3")),
+      Compile / PB.targets := Seq(
+        (
+          genModule("scalapb.ScalaPbCodeGenerator$"),
+          Seq("scala3_sources")
+        ) -> (Compile / sourceManaged).value
+      )
     )
   )
   .jsPlatform(
     Seq(Scala212, Scala213, Scala3),
     settings = Seq(
-      Compile / PB.includePaths += (ThisBuild / baseDirectory).value / "protobuf"
+      Compile / PB.includePaths += (ThisBuild / baseDirectory).value / "protobuf",
+      Compile / PB.targets := Seq(
+        genModule("scalapb.ScalaPbCodeGenerator$") -> (Compile / sourceManaged).value
+      )
     )
   )
   .settings(e2eCommonSettings)
@@ -389,10 +436,10 @@ lazy val e2e = (projectMatrix in file("e2e"))
                          )
                        else Nil),
     PB.protocVersion := versions.protobuf,
-    Compile / PB.protocOptions += "--experimental_allow_proto3_optional",
-    Compile / PB.targets := Seq(
-      genModule("scalapb.ScalaPbCodeGenerator$") -> (Compile / sourceManaged).value
-    )
+    Compile / PB.protoSources ++= (if (isScala3.value)
+                                     Seq(sourceDirectory.value / "main" / "protobuf-scala3")
+                                   else Nil),
+    Compile / PB.protocOptions += "--experimental_allow_proto3_optional"
   )
 
 lazy val conformance = (projectMatrix in file("conformance"))

compiler-plugin/src/main/scala/scalapb/GeneratorOption.scala

@@ -30,4 +30,8 @@ object GeneratorOption {
   case object RetainSourceCodeInfo extends GeneratorOption {
     override def toString = "retain_source_code_info"
   }
+
+  case object Scala3Sources extends GeneratorOption {
+    override def toString = "scala3_sources"
+  }
 }

compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala

@@ -757,6 +757,8 @@ class DescriptorImplicits private[compiler] (
         .map(Helper.escapeComment)
         .filter(_.nonEmpty)
     }
+
+    def V: ScalaCompatConstants = message.getFile.V
   }
 
   implicit class ExtendedEnumDescriptor(val enumDescriptor: EnumDescriptor) {
@@ -929,6 +931,10 @@ class DescriptorImplicits private[compiler] (
       else file.getPackage
     }
 
+    def emitScala3Sources: Boolean = scalaOptions.getScala3Sources || params.scala3Sources
+
+    def V: ScalaCompatConstants = new ScalaCompatConstants(emitScala3Sources)
+
     def javaPackageAsSymbol: String =
       javaPackage.split('.').map(_.asSymbol).mkString(".")
 
@@ -1185,6 +1191,26 @@ object DescriptorImplicits {
     }
 }
 
+// For constants that depends on the Scala 2 or 3 mode.
+private[scalapb] class ScalaCompatConstants(emitScala3Sources: Boolean) {
+  val WildcardType: String =
+    if (emitScala3Sources) "?" else "_"
+
+  val WildcardImport: String = if (emitScala3Sources) "*" else "_"
+
+  val CompSeqType: String =
+    s"Seq[_root_.scalapb.GeneratedMessageCompanion[$WildcardType <: _root_.scalapb.GeneratedMessage]]"
+
+  val PrivateThis: String =
+    if (emitScala3Sources) "private" else "private[this]"
+
+  val WithOperator: String = if (emitScala3Sources) " & " else " with "
+
+  val MessageLens =
+    if (emitScala3Sources) "_root_.scalapb.lenses.MessageLens"
+    else "_root_.scalapb.lenses.ObjectLens"
+}
+
 object Helper {
   def makeUniqueNames[T](values: Seq[(T, String)]): Map[T, String] = {
     val newNameMap: Map[String, T] =

compiler-plugin/src/main/scala/scalapb/compiler/GeneratorParams.scala

@@ -7,7 +7,8 @@ case class GeneratorParams(
     singleLineToProtoString: Boolean = false,
     asciiFormatToString: Boolean = false,
     lenses: Boolean = true,
-    retainSourceCodeInfo: Boolean = false
+    retainSourceCodeInfo: Boolean = false,
+    scala3Sources: Boolean = false
 )
 
 object GeneratorParams {
@@ -49,6 +50,8 @@ object GeneratorParams {
             case "no_lenses" => Right((params.copy(lenses = false), unrecognized))
             case "retain_source_code_info" =>
               Right((params.copy(retainSourceCodeInfo = true), unrecognized))
+            case "scala3_sources" =>
+              Right((params.copy(scala3Sources = true), unrecognized))
             case p => Right((params, unrecognized :+ p))
           }
         case (l, _) => l

compiler-plugin/src/main/scala/scalapb/compiler/GrpcServicePrinter.scala

@@ -39,7 +39,9 @@ final class GrpcServicePrinter(service: ServiceDescriptor, implicits: Descriptor
     p.call(generateScalaDoc(service))
       .add(s"trait ${service.name} extends _root_.scalapb.grpc.AbstractService {")
       .indent
-      .add(s"override def serviceCompanion = ${service.name}")
+      .add(
+        s"override def serviceCompanion: _root_.scalapb.grpc.ServiceCompanion[${service.name}] = ${service.name}"
+      )
       .print(service.methods) { case (p, method) =>
         p.call(generateScalaDoc(method)).add(serviceMethodSignature(method, overrideSig = false))
       }
@@ -69,7 +71,9 @@ final class GrpcServicePrinter(service: ServiceDescriptor, implicits: Descriptor
     p.call(generateScalaDoc(service))
       .add(s"trait ${service.blockingClient} {")
       .indent
-      .add(s"def serviceCompanion = ${service.name}")
+      .add(
+        s"def serviceCompanion: _root_.scalapb.grpc.ServiceCompanion[${service.name}] = ${service.name}"
+      )
       .print(service.methods.filter(_.canBeBlocking)) { case (p, method) =>
         p.call(generateScalaDoc(method)).add(blockingMethodSignature(method, overrideSig = false))
       }