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, 14 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/typer/ProtoTypes.scala b/src/dotty/tools/dotc/typer/ProtoTypes.scala
index b4068408b..74be3f4cd 100644
--- a/src/dotty/tools/dotc/typer/ProtoTypes.scala
+++ b/src/dotty/tools/dotc/typer/ProtoTypes.scala
@@ -187,6 +187,20 @@ object ProtoTypes {
       typer.adapt(targ, formal)
     }
 
+    private var myTupled: Type = NoType
+
+    /** The same proto-type but with all arguments combined in a single tuple */
+    def tupled: FunProto = myTupled match {
+      case pt: FunProto =>
+        pt
+      case _ =>
+        myTupled = new FunProto(untpd.Tuple(args) :: Nil, resultType, typer)
+        tupled
+    }
+
+    /** Somebody called the `tupled` method of this prototype */
+    def isTupled: Boolean = myTupled.isInstanceOf[FunProto]
+
     override def toString = s"FunProto(${args mkString ","} => $resultType)"
 
     def map(tm: TypeMap)(implicit ctx: Context): FunProto =