Added auto-tupling.

Auto-tupling should satisfy the following spec.

1. An application `f(args)` where `f` is a non-overloaded method which has a single, non-repeated parameter as its
first parameter list and where args consists of two or more arguments is expanded to `f((args))`.

2. A constructor pattern `C(args)` where `C.unapply` is a non-overloaded method which has a single, non-repeated parameter as its first parameter list and where args consists of two or more arguments is expanded to `C((args))`.

Auto-tupling can be disabled by language feature "noAutoTupling".

Conflicts:
	test/dotc/tests.scala

1 files changed, 10 insertions, 2 deletions

diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 17c77be89..f961a4544 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -1072,8 +1072,16 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
       }
     }
 
-    def adaptToArgs(wtp: Type, pt: FunProto) = wtp match {
-      case _: MethodType | _: PolyType => tree
+    def adaptToArgs(wtp: Type, pt: FunProto): Tree = wtp match {
+      case _: MethodType | _: PolyType =>
+        def isUnary = wtp.firstParamTypes match {
+          case ptype :: Nil => !ptype.isRepeatedParam
+          case _ => false
+        }
+        if (pt.args.lengthCompare(1) > 0 && isUnary && ctx.canAutoTuple)
+          adaptToArgs(wtp, pt.tupled)
+        else
+          tree
       case _ => tryInsertApply(tree, pt) {
         val more = tree match {
           case Apply(_, _) => " more"