Fix #1385: Temporarily lift 22 limit for functions

Author: odersky

src/dotty/tools/dotc/core/Definitions.scala

@@ -12,7 +12,13 @@ import collection.mutable
 import scala.reflect.api.{ Universe => ApiUniverse }
 
 object Definitions {
-  val MaxFunctionArity, MaxTupleArity = 22
+  val MaxTupleArity, MaxAbstractFunctionArity = 22
+  val MaxFunctionArity = 24
+    // Awaiting a definite solution that drops the limit altogether, 44 gives a safety
+    // margin over the previous 22, so that treecopiers in miniphases are allowed to
+    // temporarily create larger closures. This is needed in lambda lift where large closures
+    // are first formed by treecopiers before they are split apart into parameters and
+    // environment in the lambdalift transform itself.
 }
 
 /** A class defining symbols and types of standard definitions
@@ -587,7 +593,7 @@ class Definitions {
 
   // ----- Symbol sets ---------------------------------------------------
 
-  lazy val AbstractFunctionType = mkArityArray("scala.runtime.AbstractFunction", MaxFunctionArity, 0)
+  lazy val AbstractFunctionType = mkArityArray("scala.runtime.AbstractFunction", MaxAbstractFunctionArity, 0)
   val AbstractFunctionClassPerRun = new PerRun[Array[Symbol]](implicit ctx => AbstractFunctionType.map(_.symbol.asClass))
   def AbstractFunctionClass(n: Int)(implicit ctx: Context) = AbstractFunctionClassPerRun()(ctx)(n)
   lazy val FunctionType = mkArityArray("scala.Function", MaxFunctionArity, 0)

src/scala/Function23.scala

@@ -0,0 +1,21 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2002-2013, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+package scala
+
+
+/** A function of 23 parameters. Used as a temporary fix until arity limit is dropped.
+ *
+ */
+trait Function23[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, -T18, -T19, -T20, -T21, -T22, -T23, +R] extends AnyRef { self =>
+  /** Apply the body of this function to the arguments.
+   *  @return   the result of function application.
+   */
+  def apply(v1: T1, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6, v7: T7, v8: T8, v9: T9, v10: T10, v11: T11, v12: T12, v13: T13, v14: T14, v15: T15, v16: T16, v17: T17, v18: T18, v19: T19, v20: T20, v21: T21, v22: T22, v23: T23): R
+
+  override def toString() = "<function23>"
+}

src/scala/Function24.scala

@@ -0,0 +1,21 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2002-2013, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+package scala
+
+
+/** A function of 24 parameters. Used as a temporary fix until arity limit is dropped.
+ *
+ */
+trait Function24[-T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, -T9, -T10, -T11, -T12, -T13, -T14, -T15, -T16, -T17, -T18, -T19, -T20, -T21, -T22, -T23, -T24, +R] extends AnyRef { self =>
+  /** Apply the body of this function to the arguments.
+   *  @return   the result of function application.
+   */
+  def apply(v1: T1, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6, v7: T7, v8: T8, v9: T9, v10: T10, v11: T11, v12: T12, v13: T13, v14: T14, v15: T15, v16: T16, v17: T17, v18: T18, v19: T19, v20: T20, v21: T21, v22: T22, v23: T23, v24: T24): R
+
+  override def toString() = "<function24>"
+}

tests/pos/i1385.scala

@@ -0,0 +1,7 @@
+object Test {
+def foo22[T](c1:T, c2:T, c3:T, c4:T, c5:T, c6:T, c7:T, c8:T, c9:T, c10:T, c11:T, c12:T, c13:T, c14:T, c15:T, c16:T, c17:T, c18:T, c19:T, c20:T, c21:T, c22:T): Int => T = {
+    (a: Int) => { // This labda ends with 23 parameters (c1 to c22 and a)
+      c22; c21; c20; c19; c18; c17; c16; c15; c14; c13; c12; c11; c10; c9; c8; c7; c6; c5; c4; c3; c2; c1
+    }
+  }
+}