Fix #16801: Scala.js: Handle Closure's of s.r.FunctionXXL.

compiler/src/dotty/tools/backend/sjs/JSCodeGen.scala

@@ -3532,13 +3532,16 @@ class JSCodeGen()(using genCtx: Context) {
       val closure = js.Closure(arrow = true, formalCaptures, formalParams, restParam, genBody, actualCaptures)
 
       if (!funInterfaceSym.exists || defn.isFunctionClass(funInterfaceSym)) {
-        assert(!funInterfaceSym.exists || defn.isFunctionClass(funInterfaceSym),
-            s"Invalid functional interface $funInterfaceSym reached the back-end")
         val formalCount = formalParams.size
         val cls = ClassName("scala.scalajs.runtime.AnonFunction" + formalCount)
         val ctorName = MethodName.constructor(
             jstpe.ClassRef(ClassName("scala.scalajs.js.Function" + formalCount)) :: Nil)
         js.New(cls, js.MethodIdent(ctorName), List(closure))
+      } else if (funInterfaceSym.name == tpnme.FunctionXXL && funInterfaceSym.owner == defn.ScalaRuntimePackageClass) {
+        val cls = ClassName("scala.scalajs.runtime.AnonFunctionXXL")
+        val ctorName = MethodName.constructor(
+            jstpe.ClassRef(ClassName("scala.scalajs.js.Function1")) :: Nil)
+        js.New(cls, js.MethodIdent(ctorName), List(closure))
       } else {
         assert(funInterfaceSym.isJSType,
             s"Invalid functional interface $funInterfaceSym reached the back-end")

library-js/src/scala/scalajs/runtime/AnonFunctionXXL.scala

@@ -0,0 +1,8 @@
+package scala.scalajs.runtime
+
+import scala.scalajs.js
+
+@inline
+final class AnonFunctionXXL(f: js.Function1[IArray[Object], Object]) extends scala.runtime.FunctionXXL {
+  override def apply(xs: IArray[Object]): Object = f(xs)
+}

project/MiMaFilters.scala

@@ -17,6 +17,9 @@ object MiMaFilters {
     ProblemFilters.exclude[MissingClassProblem]("scala.util.boundary$Break"),
     ProblemFilters.exclude[MissingClassProblem]("scala.util.boundary$Label"),
 
+    // Scala.js only: new runtime support class in 3.2.3; not available to users
+    ProblemFilters.exclude[MissingClassProblem]("scala.scalajs.runtime.AnonFunctionXXL"),
+
     //  New experimental features in 3.3.X
     ProblemFilters.exclude[MissingFieldProblem]("scala.runtime.stdLibPatches.language#experimental.clauseInterleaving"),
     ProblemFilters.exclude[MissingClassProblem]("scala.runtime.stdLibPatches.language$experimental$clauseInterleaving$"),

tests/run/functionXXL.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 object Test {
 
   val f = (x1: Int,

tests/run/i2004.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 object Test {
   def main(args: Array[String]) = {
 

tests/run/implicitFunctionXXL.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 object Test {
 
   def main(args: Array[String]): Unit = {

tests/run/tupled-function-andThen.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 import scala.util.TupledFunction
 
 object Test {

tests/run/tupled-function-apply.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 import scala.util.TupledFunction
 
 object Test {
@@ -119,4 +117,4 @@ object Test {
     */
   extension [F, Args <: Tuple, R](f: F) def apply (args: Args)(using tf: TupledFunction[F, Args => R]): R =
     tf.tupled(f)(args)
-}
+}

tests/run/tupled-function-compose.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 import scala.util.TupledFunction
 object Test {
   def main(args: Array[String]): Unit = {

tests/run/tupled-function-extension-method.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 import scala.util.TupledFunction
 object Test {
   def main(args: Array[String]): Unit = {
@@ -13,7 +11,7 @@ object Test {
         (x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15, x16, x17, x18, x19, x20, x21, x22, x23, x24, x25)
     )
 
-    println(f0())
+    portablePrintln(f0())
     println(f1(1))
     println(f2(1, 2))
     println(f3(1, 2, 3))
@@ -34,6 +32,10 @@ object Test {
 
   }
 
+  def portablePrintln(x: Any): Unit =
+    if x == () then println("()")
+    else println(x)
+
   class Expr[T](val x: T)
 
   // Specialized only for arity 0 and one as auto tupling will not provide the disired effect
@@ -50,4 +52,4 @@ object Test {
   extension [F, Args <: Tuple, R](e: Expr[F]) def applyGiven (args: Args)(using tf: TupledFunction[F, Args ?=> R]): R =
     tf.tupled(e.x)(using args)
 
-}
+}

tests/run/tupled-function-tupled.scala

@@ -1,5 +1,3 @@
-// scalajs: --skip --pending
-
 import scala.util.TupledFunction
 
 object Test {