Fix tests

- tests/pos/automatic-tupling-of-function-parameters.scala

  This test requires dealiasing.

- tests/run/function-arity.scala

  This test requires widen ExprType.

- tests/pos/i6199a.scala

  It uses a feature which should not be supported.

Author: liufengyun

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -116,7 +116,7 @@ object Applications {
   }
 
   def tupleComponentTypes(tp: Type)(using Context): List[Type] =
-    tp match
+    tp.widenExpr.dealias match
     case tp: AppliedType =>
       if defn.isTupleClass(tp.tycon.typeSymbol) then
         tp.args

tests/pos/i6199a.scala

@@ -3,6 +3,6 @@ case class ValueWithEncoder[T](value: T, encoder: Encoder[T])
 
 object Test {
   val a: Seq[ValueWithEncoder[_]] = Seq.empty
-  val b = a.map((value, encoder) => encoder.encode(value))
+  val b = a.map(ve => ve.encode(ve.value, ve.encoder))
   val c: Seq[String] = b
 }

tests/run/i10958.scala

@@ -4,5 +4,5 @@ object U:
 @main
 def Test =
   "" match
-  case s"${U(u)})" =>
+  case s"${U(u)}" =>
     val x: String = u