[1.6.x] compiler: account for Scala 2 and 3 differences in generated varargs code (backport #737) by @ahjohannessen

.gitignore

@@ -14,4 +14,10 @@ project/plugins/project/
 .scala_dependencies
 .idea
 
+.vscode/
+
+# Metals
+.metals/
 .bloop/
+project/metals.sbt
+metals.sbt

compiler/src/main/java/play/japi/twirl/compiler/TwirlCompiler.java

@@ -62,6 +62,7 @@ public static Optional<File> compile(
       List<String> constructorAnnotations,
       Codec codec,
       boolean inclusiveDot) {
+    String scalaVersion = play.twirl.compiler.BuildInfo$.MODULE$.scalaVersion();
     Seq<String> scalaAdditionalImports =
         JavaConverters$.MODULE$
             .asScalaBufferConverter(new ArrayList<String>(additionalImports))
@@ -75,6 +76,7 @@ public static Optional<File> compile(
             sourceDirectory,
             generatedDirectory,
             formatterType,
+            scala.Option.apply(scalaVersion),
             scalaAdditionalImports,
             scalaConstructorAnnotations,
             codec,

compiler/src/main/scala/play/twirl/compiler/TwirlCompiler.scala

@@ -162,6 +162,17 @@ case class GeneratedSourceVirtual(path: String) extends AbstractGeneratedSource
 
 object TwirlCompiler {
 
+  // For constants that depend on Scala 2 or 3 mode.
+  private[compiler] class ScalaCompat(emitScala3Sources: Boolean) {
+    val varargSplicesSyntax: String =
+      if (emitScala3Sources) "*" else ": _*"
+  }
+
+  private[compiler] object ScalaCompat {
+    def apply(scalaVersion: Option[String]): ScalaCompat =
+      new ScalaCompat(scalaVersion.exists(_.startsWith("3.")))
+  }
+
   def defaultImports(scalaVersion: String) = {
     val implicits = if (scalaVersion.startsWith("3.")) {
       Seq(
@@ -199,7 +210,30 @@ object TwirlCompiler {
       constructorAnnotations: collection.Seq[String] = Nil,
       codec: Codec = TwirlIO.defaultCodec,
       inclusiveDot: Boolean = false
-  ) = {
+  ): Option[File] =
+    compile(
+      source,
+      sourceDirectory,
+      generatedDirectory,
+      formatterType,
+      None,
+      additionalImports,
+      constructorAnnotations,
+      codec,
+      inclusiveDot
+    )
+
+  def compile(
+      source: File,
+      sourceDirectory: File,
+      generatedDirectory: File,
+      formatterType: String,
+      scalaVersion: Option[String],
+      additionalImports: collection.Seq[String],
+      constructorAnnotations: collection.Seq[String],
+      codec: Codec,
+      inclusiveDot: Boolean
+  ): Option[File] = {
     val resultType = formatterType + ".Appendable"
     val (templateName, generatedSource) =
       generatedFile(source, codec, sourceDirectory, generatedDirectory, inclusiveDot)
@@ -211,6 +245,7 @@ object TwirlCompiler {
         relativePath(source),
         resultType,
         formatterType,
+        scalaVersion,
         additionalImports,
         constructorAnnotations,
         inclusiveDot
@@ -232,7 +267,33 @@ object TwirlCompiler {
       constructorAnnotations: collection.Seq[String] = Nil,
       codec: Codec = TwirlIO.defaultCodec,
       inclusiveDot: Boolean = false
-  ) = {
+  ): GeneratedSourceVirtual =
+    compileVirtual(
+      content,
+      source,
+      sourceDirectory,
+      resultType,
+      formatterType,
+      None,
+      additionalImports,
+      constructorAnnotations,
+      codec,
+      inclusiveDot
+    )
+
+  def compileVirtual(
+      content: String,
+      source: File,
+      sourceDirectory: File,
+      resultType: String,
+      formatterType: String,
+      scalaVersion: Option[String],
+      additionalImports: collection.Seq[String],
+      constructorAnnotations: collection.Seq[String],
+      codec: Codec,
+      inclusiveDot: Boolean
+  ): GeneratedSourceVirtual = {
+
     val (templateName, generatedSource) = generatedFileVirtual(source, sourceDirectory, inclusiveDot)
     val generated = parseAndGenerateCode(
       templateName,
@@ -241,6 +302,7 @@ object TwirlCompiler {
       relativePath(source),
       resultType,
       formatterType,
+      scalaVersion,
       additionalImports,
       constructorAnnotations,
       inclusiveDot
@@ -262,7 +324,31 @@ object TwirlCompiler {
       additionalImports: collection.Seq[String],
       constructorAnnotations: collection.Seq[String],
       inclusiveDot: Boolean
-  ) = {
+  ): String = parseAndGenerateCode(
+    templateName,
+    content,
+    codec,
+    relativePath,
+    resultType,
+    formatterType,
+    None,
+    additionalImports,
+    constructorAnnotations,
+    inclusiveDot
+  )
+
+  private def parseAndGenerateCode(
+      templateName: Array[String],
+      content: Array[Byte],
+      codec: Codec,
+      relativePath: String,
+      resultType: String,
+      formatterType: String,
+      scalaVersion: Option[String],
+      additionalImports: collection.Seq[String],
+      constructorAnnotations: collection.Seq[String],
+      inclusiveDot: Boolean
+  ): String = {
     val templateParser = new TwirlParser(inclusiveDot)
     templateParser.parse(new String(content, codec.charSet)) match {
       case templateParser.Success(parsed: Template, rest) if rest.atEnd() => {
@@ -274,6 +360,7 @@ object TwirlCompiler {
           parsed,
           resultType,
           formatterType,
+          ScalaCompat(scalaVersion),
           additionalImports,
           constructorAnnotations
         )
@@ -448,8 +535,29 @@ object TwirlCompiler {
       formatterType: String,
       additionalImports: collection.Seq[String],
       constructorAnnotations: collection.Seq[String]
+  ): collection.Seq[Any] = generateCode(
+    packageName,
+    name,
+    root,
+    resultType,
+    formatterType,
+    ScalaCompat(None),
+    additionalImports,
+    constructorAnnotations
+  )
+
+  private def generateCode(
+      packageName: String,
+      name: String,
+      root: Template,
+      resultType: String,
+      formatterType: String,
+      scalaCompat: ScalaCompat,
+      additionalImports: collection.Seq[String],
+      constructorAnnotations: collection.Seq[String]
   ): collection.Seq[Any] = {
-    val (renderCall, f, templateType) = TemplateAsFunctionCompiler.getFunctionMapping(root.params.str, resultType)
+    val (renderCall, f, templateType) =
+      TemplateAsFunctionCompiler.getFunctionMapping(root.params.str, resultType, scalaCompat)
 
     // Get the imports that we need to include, filtering out empty imports
     val imports: Seq[Any] = Seq(additionalImports.map(i => Seq("import ", i, "\n")), formatImports(root.topImports))
@@ -509,9 +617,42 @@ package """ :+ packageName :+ """
       formatterType: String,
       additionalImports: collection.Seq[String],
       constructorAnnotations: collection.Seq[String]
+  ): String = generateFinalTemplate(
+    relativePath,
+    contents,
+    packageName,
+    name,
+    root,
+    resultType,
+    formatterType,
+    ScalaCompat(None),
+    additionalImports,
+    constructorAnnotations
+  )
+
+  private def generateFinalTemplate(
+      relativePath: String,
+      contents: Array[Byte],
+      packageName: String,
+      name: String,
+      root: Template,
+      resultType: String,
+      formatterType: String,
+      scalaCompat: ScalaCompat,
+      additionalImports: collection.Seq[String],
+      constructorAnnotations: collection.Seq[String]
   ): String = {
     val generated =
-      generateCode(packageName, name, root, resultType, formatterType, additionalImports, constructorAnnotations)
+      generateCode(
+        packageName,
+        name,
+        root,
+        resultType,
+        formatterType,
+        scalaCompat,
+        additionalImports,
+        constructorAnnotations
+      )
 
     Source.finalSource(relativePath, contents, generated, Hash(contents, additionalImports))
   }
@@ -531,7 +672,17 @@ package """ :+ packageName :+ """
         }
     }
 
-    def getFunctionMapping(signature: String, returnType: String): (String, String, String) = {
+    def getFunctionMapping(
+        signature: String,
+        returnType: String,
+    ): (String, String, String) =
+      getFunctionMapping(signature, returnType, ScalaCompat(None))
+
+    private[compiler] def getFunctionMapping(
+        signature: String,
+        returnType: String,
+        sc: ScalaCompat
+    ): (String, String, String) = {
 
       val params: List[List[Term.Param]] =
         try {
@@ -573,7 +724,7 @@ package """ :+ packageName :+ """
               .map { p =>
                 p.name.toString + Option(p.decltpe.get.toString)
                   .filter(_.endsWith("*"))
-                  .map(_ => ".toIndexedSeq:_*")
+                  .map(_ => s".toIndexedSeq${sc.varargSplicesSyntax}")
                   .getOrElse("")
               }
               .mkString(",") + ")"
@@ -601,7 +752,7 @@ package """ :+ packageName :+ """
               .map { p =>
                 p.name.toString + Option(p.decltpe.get.toString)
                   .filter(_.endsWith("*"))
-                  .map(_ => ".toIndexedSeq:_*")
+                  .map(_ => s".toIndexedSeq${sc.varargSplicesSyntax}")
                   .getOrElse("")
               }
               .mkString(",") + ")"

compiler/src/test/scala-2/play/twirl/compiler/test/Helper.scala

@@ -6,11 +6,12 @@ package play.twirl.compiler
 package test
 
 import java.io._
+import play.twirl.parser.TwirlIO
 
 object Helper {
   case class CompilationError(message: String, line: Int, column: Int) extends RuntimeException(message)
 
-  class CompilerHelper(sourceDir: File, generatedDir: File, generatedClasses: File) {
+  class CompilerHelper(sourceDir: File, val generatedDir: File, generatedClasses: File) {
     import java.net._
     import scala.collection.mutable
     import scala.reflect.internal.util.Position
@@ -99,7 +100,11 @@ object Helper {
         sourceDir,
         generatedDir,
         "play.twirl.api.HtmlFormat",
-        additionalImports = TwirlCompiler.defaultImports(scalaVersion) ++ additionalImports
+        Option(scalaVersion),
+        additionalImports = TwirlCompiler.defaultImports(scalaVersion) ++ additionalImports,
+        constructorAnnotations = Nil,
+        codec = TwirlIO.defaultCodec,
+        inclusiveDot = false
       )
 
       val mapper = GeneratedSource(generated)

compiler/src/test/scala-3/play/twirl/compiler/test/Helper.scala

@@ -20,11 +20,12 @@ import dotty.tools.io.PlainDirectory
 import dotty.tools.io.Directory
 import dotty.tools.io.ClassPath
 import scala.jdk.CollectionConverters._
+import play.twirl.parser.TwirlIO
 
 object Helper {
   case class CompilationError(message: String, line: Int, column: Int) extends RuntimeException(message)
 
-  class CompilerHelper(sourceDir: File, generatedDir: File, generatedClasses: File) {
+  class CompilerHelper(sourceDir: File, val generatedDir: File, generatedClasses: File) {
     import java.net._
     import scala.collection.mutable
 
@@ -60,14 +61,22 @@ object Helper {
     ): CompiledTemplate[T] = {
       val scalaVersion = play.twirl.compiler.BuildInfo.scalaVersion
       val templateFile = new File(sourceDir, templateName)
-      val Some(generated) = twirlCompiler.compile(
+      val generatedOpt: Option[File] = twirlCompiler.compile(
         templateFile,
         sourceDir,
         generatedDir,
         "play.twirl.api.HtmlFormat",
-        additionalImports = TwirlCompiler.defaultImports(scalaVersion) ++ additionalImports
+        Option(scalaVersion),
+        additionalImports = TwirlCompiler.defaultImports(scalaVersion) ++ additionalImports,
+        constructorAnnotations = Nil,
+        codec = TwirlIO.defaultCodec,
+        inclusiveDot = false
       )
 
+      val generated = generatedOpt.getOrElse {
+        throw new FileNotFoundException(s"Could not find generated file for $templateName")
+      }
+
       val mapper = GeneratedSource(generated)
 
       val compilerArgs = Array(
@@ -94,7 +103,10 @@ object Helper {
 
     class TestDriver(outDir: Path, compilerArgs: Array[String], path: Path) extends Driver {
       def compile(): Reporter = {
-        val Some((toCompile, rootCtx)) = setup(compilerArgs :+ path.toAbsolutePath.toString, initCtx.fresh)
+        val setupOpt = setup(compilerArgs :+ path.toAbsolutePath.toString, initCtx.fresh)
+        val (toCompile, rootCtx) = setupOpt.getOrElse {
+          throw new Exception("Failed to initialize compiler")
+        }
 
         val silentReporter = new ConsoleReporter.AbstractConsoleReporter {
           def printMessage(msg: String): Unit = {