Small cleanup

[Cherry-picked 309034e]

Author: KacperFKorban

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -1237,15 +1237,11 @@ object desugar {
         name -> ctxBounds
     }.flatMap { case (name, ctxBounds) =>
       ctxBounds.map { ctxBound =>
-        idx = idx + 1
-        ctxBound match
-          case ctxBound @ ContextBoundTypeTree(tycon, paramName, ownName) =>
-            if tree.isTerm then
-              ValDef(ownName, ctxBound, EmptyTree).withFlags(TermParam | Given)
-            else
-              ContextBoundTypeTree(tycon, paramName, EmptyTermName) // this has to be handled in Typer#typedFunctionType
-          case _ =>
-            makeSyntheticParameter(idx, ctxBound).withAddedFlags(Given)
+        val ContextBoundTypeTree(tycon, paramName, ownName) = ctxBound: @unchecked
+        if tree.isTerm then
+          ValDef(ownName, ctxBound, EmptyTree).withFlags(TermParam | Given)
+        else
+          ContextBoundTypeTree(tycon, paramName, EmptyTermName) // this has to be handled in Typer#typedFunctionType
       }
     }
     val contextFunctionResult =

tests/pos/contextbounds-for-poly-functions.scala

@@ -16,3 +16,5 @@ val less3: Comparer = [X: Ord as ord] => (x: X, y: X) => ord.compare(x, y) < 0
 // type Cmp[X] = (x: X, y: X) => Boolean
 // type Comparer2 = [X: Ord] => Cmp[X]
 // val less4: Comparer2 = [X: Ord] => (x: X, y: X) => summon[Ord[X]].compare(x, y) < 0
+
+val less5 = [X: [X] =>> Ord[X]] => (x: X, y: X) => summon[Ord[X]].compare(x, y) < 0