Add a Scala3Renderer

src/main/scala/sbtbuildinfo/BuildInfoPlugin.scala

@@ -110,6 +110,6 @@ object BuildInfoPlugin extends AutoPlugin {
     buildInfoKeys    := Seq(name, version, scalaVersion, sbtVersion),
     buildInfoBuildNumber := buildNumberTask(baseDirectory.value, 1),
     buildInfoOptions := Seq(),
-    buildInfoRenderFactory := ScalaCaseObjectRenderer.apply
+    buildInfoRenderFactory := (if(scalaVersion.value.startsWith("3")) Scala3CaseObjectRenderer.apply else ScalaCaseObjectRenderer.apply)
   )
 }

src/main/scala/sbtbuildinfo/Scala3CaseClassRenderer.scala

@@ -0,0 +1,66 @@
+package sbtbuildinfo
+
+case class Scala3CaseClassRenderer(options: Seq[BuildInfoOption], pkg: String, obj: String) extends Scala3Renderer {
+  override def fileType = BuildInfoType.Source
+  override def extension = "scala"
+
+  val traitNames = options.collect{case BuildInfoOption.Traits(ts @ _*) => ts}.flatten
+  val objTraits = if (traitNames.isEmpty) "" else "extends " ++ traitNames.mkString(" with ")
+
+  // It is safe to add `import scala.Predef` even though we need to keep `-Ywarn-unused-import` in mind
+  // because we always generate code that has a reference to `String`. If the "base" generated code were to be
+  // changed and no longer contain a reference to `String`, we would need to remove `import scala.Predef` and
+  // fully qualify every reference. Note it is NOT safe to use `import scala._` because of the possibility of
+  // the project using `-Ywarn-unused-import` because we do not always generated references that are part of
+  // `scala` such as `scala.Option`.
+  val importScalaPredef = options.contains(BuildInfoOption.ImportScalaPredef)
+  def header = List(
+    "// $COVERAGE-OFF$",
+    s"package $pkg",
+    ""
+  )
+  val imports = if (importScalaPredef) List(
+    "import scala.Predef.*",
+    ""
+  ) else Nil
+  val generateComment = List(
+    s"/** This file was generated by sbt-buildinfo. */"
+  )
+
+  def footer = List("// $COVERAGE-ON$")
+
+  override def renderKeys(buildInfoResults: Seq[BuildInfoResult]) =
+    header ++ imports ++ generateComment ++
+    caseClassDefinitionBegin ++
+      buildInfoResults.flatMap(caseClassParameter).mkString(",\n").split("\n") ++
+      caseClassDefinitionEnd ++
+      toMapLines(buildInfoResults) ++
+      toJsonLines ++
+      caseClassEnd ++
+      List("") ++
+      caseObjectLine(buildInfoResults) ++
+      footer
+
+  private def caseClassDefinitionBegin = List(
+    withPkgPriv(s"case class $obj(")
+  )
+
+  private def caseClassParameter(r: BuildInfoResult): Seq[String] = {
+    val typeDecl = getType(r.typeExpr) getOrElse "scala.Any"
+
+    List(
+      s"  ${r.identifier}: $typeDecl"
+    )
+  }
+
+  private def caseClassDefinitionEnd = List(s") $objTraits {", "")
+  private def caseClassEnd = List("}")
+
+  private def caseObjectLine(buildInfoResults: Seq[BuildInfoResult]) = List(
+    withPkgPriv(s"case object $obj {"),
+    s"  def apply(): $obj = new $obj(${buildInfoResults.map(r => s"\n    ${r.identifier} = ${quote(r.value)}").mkString(",")})",
+    s"  val get = apply()",
+    s"  val value = apply()",
+    s"}"
+  )
+}

src/main/scala/sbtbuildinfo/Scala3CaseObjectRenderer.scala

@@ -0,0 +1,71 @@
+package sbtbuildinfo
+
+case class Scala3CaseObjectRenderer(options: Seq[BuildInfoOption], pkg: String, obj: String) extends Scala3Renderer {
+
+  override def fileType = BuildInfoType.Source
+  override def extension = "scala"
+  val traitNames = options.collect{case BuildInfoOption.Traits(ts @ _*) => ts}.flatten
+  val objTraits = if (traitNames.isEmpty) "" else " extends " ++ traitNames.mkString(" with ")
+  val constantValue = options.contains(BuildInfoOption.ConstantValue)
+
+  // It is safe to add `import scala.Predef` even though we need to keep `-Ywarn-unused-import` in mind
+  // because we always generate code that has a reference to `String`. If the "base" generated code were to be
+  // changed and no longer contain a reference to `String`, we would need to remove `import scala.Predef` and
+  // fully qualify every reference. Note it is NOT safe to use `import scala._` because of the possibility of
+  // the project using `-Ywarn-unused-import` because we do not always generated references that are part of
+  // `scala` such as `scala.Option`.
+  val importScalaPredef = options.contains(BuildInfoOption.ImportScalaPredef)
+  def header = List(
+    "// $COVERAGE-OFF$",
+    s"package $pkg",
+    ""
+  )
+  val imports = if (importScalaPredef) List(
+    "import scala.Predef.*",
+    ""
+  ) else Nil
+  val objectHeader = List(
+    s"/** This object was generated by sbt-buildinfo. */",
+    withPkgPriv(s"case object $obj$objTraits {")
+  )
+
+  def footer = List("}", "// $COVERAGE-ON$")
+
+  override def renderKeys(buildInfoResults: Seq[BuildInfoResult]) =
+    header ++ imports ++ objectHeader ++
+    buildInfoResults.flatMap(line) ++
+    Seq(toStringLines(buildInfoResults)) ++
+    toMapLines(buildInfoResults) ++
+    toJsonLines ++
+    footer
+
+  private val constantTypes = Set("scala.Int", "scala.Long", "scala.Double", "scala.Boolean", "scala.Symbol", "String")
+
+  private def line(result: BuildInfoResult): Seq[String] = {
+    import result._
+    val (typeDecl, modifier) =
+      getType(result.typeExpr) match {
+        case Some(tp) if !constantValue || !constantTypes(tp) =>
+          (s": $tp", "")
+        case _ if constantValue =>
+          ("", "final ")
+        case _ =>
+          ("", "")
+      }
+    List(
+      s"  /** The value is ${quote(value)}. */",
+      s"  ${modifier}val $identifier$typeDecl = ${quote(value)}"
+    )
+  }
+
+  def toStringLines(results: Seq[BuildInfoResult]): String = {
+    val idents = results.map(_.identifier)
+    val fmt = idents.map("%s: %%s" format _).mkString(", ")
+    val vars = idents.mkString(", ")
+    s"""  override val toString: String = {
+         |    "$fmt".format(
+         |      $vars
+         |    )
+         |  }""".stripMargin
+  }
+}

src/main/scala/sbtbuildinfo/Scala3Renderer.scala

@@ -0,0 +1,29 @@
+package sbtbuildinfo
+
+abstract class Scala3Renderer extends ScalaRenderer {
+
+  override protected def toJsonLines: Seq[String] =
+    if (options contains BuildInfoOption.ToJson)
+      List(
+         """|  private def quote(x: scala.Any): String = "\"" + x + "\""
+            |  private def toJsonValue[T <: Matchable](value: T): String = {
+            |    value match {
+            |      case elem: scala.collection.Seq[? <: Matchable] => elem.map(toJsonValue).mkString("[", ",", "]")
+            |      case elem: scala.Option[? <: Matchable] => elem.map(toJsonValue).getOrElse("null")
+            |      case elem: scala.collection.Map[?, ? <: Matchable] => elem.map {
+            |        case (k, v) => toJsonValue(k.toString) + ":" + toJsonValue(v)
+            |      }.mkString("{", ", ", "}")
+            |      case d: scala.Double => d.toString
+            |      case f: scala.Float => f.toString
+            |      case l: scala.Long => l.toString
+            |      case i: scala.Int => i.toString
+            |      case s: scala.Short => s.toString
+            |      case bool: scala.Boolean => bool.toString
+            |      case str: String => quote(str)
+            |      case other => quote(other.toString)
+            |    }
+            |  }
+            |
+            |  val toJson: String = toJsonValue(toMap)""".stripMargin)
+    else Nil
+}