update docs for (partial) fun synth in uncurry

Author: Adriaan Moors

src/compiler/scala/tools/nsc/transform/UnCurry.scala

@@ -225,38 +225,15 @@ abstract class UnCurry extends InfoTransform
     }
 
 
-    /*  Transform a function node (x_1,...,x_n) => body of type FunctionN[T_1, .., T_N, R] to
+    /**  Transform a function node (x_1,...,x_n) => body of type FunctionN[T_1, .., T_N, R] to
      *
      *    class $anon() extends AbstractFunctionN[T_1, .., T_N, R] with Serializable {
      *      def apply(x_1: T_1, ..., x_N: T_n): R = body
      *    }
      *    new $anon()
      *
-     *  transform a function node (x => body) of type PartialFunction[T, R] where
-     *    body = expr match { case P_i if G_i => E_i }_i=1..n
-     *  to:
+     * If `settings.XoldPatmat.value`, also synthesized AbstractPartialFunction subclasses (see synthPartialFunction).
      *
-     //TODO: correct code template below
-     *    class $anon() extends AbstractPartialFunction[T, R] with Serializable {
-     *      def applyOrElse[A1 <: A, B1 >: B](x: A1, default: A1 => B1): B1 = (expr: @unchecked) match {
-     *        case P_1 if G_1 => E_1
-     *        ...
-     *        case P_n if G_n => E_n
-     *        case _ => default(expr)
-     *      }
-     *      def isDefinedAt(x: T): boolean = (x: @unchecked) match {
-     *        case P_1 if G_1 => true
-     *        ...
-     *        case P_n if G_n => true
-     *        case _ => false
-     *      }
-     *    }
-     *    new $anon()
-     *
-     *  However, if one of the patterns P_i if G_i is a default pattern,
-     *  drop the last default clause in the definition of `apply` and generate for `_isDefinedAt` instead
-     *
-     *      def isDefinedAtCurrent(x: T): boolean = true
      */
     def transformFunction(fun: Function): Tree =
       deEta(fun) match {
@@ -300,6 +277,28 @@ abstract class UnCurry extends InfoTransform
 
       }
 
+    /** Transform a function node (x => body) of type PartialFunction[T, R] where
+     *    body = expr match { case P_i if G_i => E_i }_i=1..n
+     *  to (assuming none of the cases is a default case):
+     *
+     *    class $anon() extends AbstractPartialFunction[T, R] with Serializable {
+     *      def applyOrElse[A1 <: A, B1 >: B](x: A1, default: A1 => B1): B1 = (expr: @unchecked) match {
+     *        case P_1 if G_1 => E_1
+     *        ...
+     *        case P_n if G_n => E_n
+     *        case _ => default(expr)
+     *      }
+     *      def isDefinedAt(x: T): boolean = (x: @unchecked) match {
+     *        case P_1 if G_1 => true
+     *        ...
+     *        case P_n if G_n => true
+     *        case _ => false
+     *      }
+     *    }
+     *    new $anon()
+     *
+     *  If there's a default case, the original match is used for applyOrElse, and isDefinedAt returns `true`
+     */
     def synthPartialFunction(fun: Function) = {
       if (!settings.XoldPatmat.value) debugwarn("Under the new pattern matching scheme, PartialFunction should have been synthesized during typers.")