[1.6.x] Support >22 args in Scala 3 (backport #747) by @mkurz

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

@@ -166,6 +166,8 @@ object TwirlCompiler {
   private[compiler] class ScalaCompat(emitScala3Sources: Boolean) {
     val varargSplicesSyntax: String =
       if (emitScala3Sources) "*" else ": _*"
+    def valueOrEmptyIfScala3(value: => String): String =
+      if (emitScala3Sources) "" else value
   }
 
   private[compiler] object ScalaCompat {
@@ -574,7 +576,8 @@ class """ :+ name :+ " " :+ constructorAnnotations :+ " " :+ Source(constructor.
 package """ :+ packageName :+ """
 
 """ :+ imports :+ """
-""" :+ classDeclaration :+ """ extends _root_.play.twirl.api.BaseScalaTemplate[""" :+ resultType :+ """,_root_.play.twirl.api.Format[""" :+ resultType :+ """]](""" :+ formatterType :+ """) with """ :+ templateType :+ """ {
+""" :+ classDeclaration :+ """ extends _root_.play.twirl.api.BaseScalaTemplate[""" :+ resultType :+ """,_root_.play.twirl.api.Format[""" :+ resultType :+ """]](""" :+ formatterType :+ """)""" :+ scalaCompat
+        .valueOrEmptyIfScala3(s" with $templateType") :+ """ {
 
   /*""" :+ root.comment.map(_.msg).getOrElse("") :+ """*/
   def apply""" :+ Source(root.params.str, root.params.pos) :+ """:""" :+ resultType :+ """ = {
@@ -732,15 +735,17 @@ package """ :+ packageName :+ """
           .mkString
       )
 
-      val templateType = "_root_.play.twirl.api.Template%s[%s%s]".format(
-        params.flatten.size,
-        params.flatten
-          .map {
-            case ByNameParam(_, paramType) => paramType
-            case p                         => filterType(p)
-          }
-          .mkString(","),
-        (if (params.flatten.isEmpty) "" else ",") + returnType
+      val templateType = sc.valueOrEmptyIfScala3(
+        "_root_.play.twirl.api.Template%s[%s%s]".format(
+          params.flatten.size,
+          params.flatten
+            .map {
+              case ByNameParam(_, paramType) => paramType
+              case p                         => filterType(p)
+            }
+            .mkString(","),
+          (if (params.flatten.isEmpty) "" else ",") + returnType
+        )
       )
 
       val f = "def f:%s = %s => apply%s".format(

sbt-twirl/src/sbt-test/twirl/compile-scala3/src/test/scala/test/Test.scala

@@ -10,4 +10,10 @@ object Test extends App {
   test(a.b.html.c.render("world"), "Hello, world.\n")
 
   test(html.template.render("42"), "Answer: 42\n")
+
+  test(
+    html.manyargstemplate.render(
+      "1", "2", "3", "5", "4", "7", "6", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26"),
+    "26 args: 1 2 3 5 4 7 6 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26\n"
+  )
 }

sbt-twirl/src/sbt-test/twirl/compile-scala3/src/test/twirl/test/manyargstemplate.scala.html

@@ -0,0 +1,6 @@
+@****************************************************************************************************************************************************
+ * Copyright (C) from 2022 The Play Framework Contributors <https://github.com/playframework>, 2011-2021 Lightbend Inc. <https://www.lightbend.com> *
+ ****************************************************************************************************************************************************@
+
+@(a: String, b: String, c: String, d: String, e: String, f: String, g: String, h: String, i: String, j: String, k: String, l: String, m: String, n: String, o: String, p: String, q: String, r: String, s: String, t: String, u: String, v: String, w: String, x: String, y: String, z: String)
+26 args: @a @b @c @d @e @f @g @h @i @j @k @l @m @n @o @p @q @r @s @t @u @v @w @x @y @z