Revert "Tweak syntax of conditions in given instances"

This reverts commit 631b5fe.

Author: odersky

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -2792,10 +2792,7 @@ object Parsers {
       var counter = nparams
       def nextIdx = { counter += 1; counter }
       val paramFlags = if ofClass then Private | Local | ParamAccessor else Param
-      val tps1 = tps match
-        case Tuple(tps1) :: Nil => tps1
-        case _ => tps
-      tps1.map(makeSyntheticParameter(nextIdx, _, paramFlags | Synthetic | Given))
+      tps.map(makeSyntheticParameter(nextIdx, _, paramFlags | Synthetic | Given))
 
     /** OLD: GivenTypes   ::=  AnnotType {‘,’ AnnotType}
      *  NEW: GivenTypes   ::=  Type {‘,’ Type}

tests/pos/tupled-given.scala

@@ -7,7 +7,7 @@ object Test extends App {
       given Show[Int] {}
       given [T]: (st: Show[T]) => Show[Tuple1[T]]
       given t2[T, U]: (st: Show[T], su: Show[U]) => Show[(T, U)]
-      given t3 [T, U, V]: (Show[T], Show[U], Show[V]) => Show[(T, U, V)]
+      given t3 [T, U, V]: (st: Show[T], su: Show[U], sv: Show[V]) => Show[(T, U, V)]
 
       def derived[T](given m: Mirror.Of[T], r: Show[m.MirroredElemTypes]): Show[T] = new Show[T] {}
     }