Fix #2004: Add forwarders to XXL functions apply method

Author: nicolasstucki

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -75,6 +75,7 @@ class Compiler {
            new AugmentScala2Traits, // Expand traits defined in Scala 2.11 to simulate old-style rewritings
            new ResolveSuper,        // Implement super accessors and add forwarders to trait methods
            new PrimitiveForwarders, // Add forwarders to trait methods that have a mismatch between generic and primitives
+           new FunctionXXLForwarders, // Add forwarders for FunctionXXL apply method
            new ArrayConstructors),  // Intercept creation of (non-generic) arrays and intrinsify.
       List(new Erasure),            // Rewrite types to JVM model, erasing all type parameters, abstract types and refinements.
       List(new ElimErasedValueType, // Expand erased value types to their underlying implmementation types

compiler/src/dotty/tools/dotc/transform/FunctionXXLForwarders.scala

@@ -0,0 +1,58 @@
+package dotty.tools.dotc
+package transform
+
+import core._
+import Constants.Constant
+import Contexts.Context
+import Flags._
+import Definitions._
+import DenotTransformers._
+import StdNames._
+import Symbols._
+import TreeTransforms._
+import Types._
+
+
+/** This phase adds forwarder for XXL functions `apply` methods that are implemented with a method
+ *  with explicit parameters (not in Array[Object]).
+ *
+ *  In particular for every method
+ *    `def apply(x1: T1, ... xn: Tn): R` in class `M` subtype of `FunctionN[T1, ..., Tn, R]` with `N` > 22
+ *  a forwarder
+ *    `def apply(xs: Array[Object]): R = this.apply(xs(0).asInstanceOf[T1], ..., xs(n-1).asInstanceOf[Tn]).asInstanceOf[R]`
+ *  is generated.
+ */
+class FunctionXXLForwarders extends MiniPhaseTransform with IdentityDenotTransformer { thisTransform =>
+  import ast.tpd._
+
+  override def phaseName: String = "functionXXLForwarders"
+
+  override def transformTemplate(impl: Template)(implicit ctx: Context, info: TransformerInfo): Template = {
+
+    def forwarderRhs(receiver: Tree, xsTree: Tree): Tree =  {
+      val argsApply = ref(xsTree.symbol).select(nme.apply)
+      var idx = -1
+      val argss = receiver.tpe.widenDealias.paramInfoss.map(_.map { param =>
+        idx += 1
+        argsApply.appliedToArgs(List(Literal(Constant(idx)))).asInstance(param)
+      })
+      ref(receiver.symbol).appliedToArgss(argss).asInstance(defn.ObjectType)
+    }
+
+    val forwarders =
+      for {
+        tree <- if (impl.symbol.owner.is(Trait)) Nil else impl.body
+        if tree.symbol.is(Method) && tree.symbol.name == nme.apply &&
+           tree.symbol.signature.paramsSig.size > MaxImplementedFunctionArity &&
+           tree.symbol.allOverriddenSymbols.exists(sym => defn.isXXLFunctionClass(sym.owner))
+      } yield {
+        val xsType = defn.ArrayType.appliedTo(List(defn.ObjectType))
+        val methType = MethodType(List(nme.args))(_ => List(xsType), _ => defn.ObjectType)
+        val meth = ctx.newSymbol(tree.symbol.owner, nme.apply, Synthetic | Method, methType)
+        DefDef(meth, paramss => forwarderRhs(tree, paramss.head.head))
+      }
+
+    cpy.Template(impl)(body = forwarders ::: impl.body)
+  }
+
+}

tests/run/i2004.check

@@ -1 +1,2 @@
-1
+2
+67

tests/run/i2004.scala

@@ -1,11 +1,19 @@
 object Test {
   def main(args: Array[String]) = {
-    val f: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int =
+
+    val f: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int = new Fun26
+    println(f.apply(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1))
+
+    val g: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int =
       {
         (x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int) =>
         x1
       }
-    println(f.apply(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1))
+    println(g.apply(67, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1))
 
   }
 }
+
+class Fun26 extends Function26[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int] {
+  def apply(x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int): Int = x2
+}

tests/run/i2004b.check

@@ -0,0 +1,2 @@
+4
+3

tests/run/i2004b.scala

@@ -0,0 +1,26 @@
+object Test {
+  def main(args: Array[String]) = {
+    val f: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int = new Fun26_1
+    println(f.apply(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1))
+
+    val g: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int = new Fun26_2
+    println(g.apply(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1))
+  }
+}
+
+
+class Fun26_1 extends Fun26_t {
+  override def apply(x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int): Int = x4
+}
+
+class Fun26_2 extends Fun26_c {
+  override def apply(x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int): Int = x3
+}
+
+trait Fun26_t extends Function26[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int] {
+  def apply(x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int): Int = x2
+}
+
+trait Fun26_c extends Function26[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int] {
+  def apply(x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int): Int = x2
+}