Convert TreeUnpickler context functions to CFTs (1)

Author: odersky

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -608,7 +608,7 @@ class TreeUnpickler(reader: TastyReader,
      *  boundary symbol.
      */
     def readModifiers[WithinType, AnnotType]
-        (end: Addr, readAnnot: Context => Symbol => AnnotType, readWithin: Context => WithinType, defaultWithin: WithinType)
+        (end: Addr, readAnnot: Context ?=> Symbol => AnnotType, readWithin: Context ?=> WithinType, defaultWithin: WithinType)
         (using Context): (FlagSet, List[Symbol => AnnotType], WithinType) = {
       var flags: FlagSet = EmptyFlags
       var annotFns: List[Symbol => AnnotType] = Nil
@@ -662,32 +662,28 @@ class TreeUnpickler(reader: TastyReader,
           case OPEN => addFlag(Open)
           case PRIVATEqualified =>
             readByte()
-            privateWithin = readWithin(ctx)
+            privateWithin = readWithin
           case PROTECTEDqualified =>
             addFlag(Protected)
-            privateWithin = readWithin(ctx)
+            privateWithin = readWithin
           case ANNOTATION =>
-            annotFns = readAnnot(ctx) :: annotFns
+            annotFns = readAnnot :: annotFns
           case tag =>
             assert(false, s"illegal modifier tag $tag at $currentAddr, end = $end")
         }
       }
       (flags, annotFns.reverse, privateWithin)
     }
 
-    private val readTypedWithin: Context => Symbol =
-      implicit ctx => readType().typeSymbol
+    private val readTypedWithin: Context ?=> Symbol = readType().typeSymbol
 
-    private val readTypedAnnot: Context => Symbol => Annotation = {
-      implicit ctx =>
-        readByte()
-        val end = readEnd()
-        val tp = readType()
-        val lazyAnnotTree = readLaterWithOwner(end, rdr => implicit ctx => rdr.readTerm())
-
-        owner =>
-          Annotation.deferredSymAndTree(tp.typeSymbol)(lazyAnnotTree(owner).complete)
-    }
+    private val readTypedAnnot: Context ?=> Symbol => Annotation =
+      readByte()
+      val end = readEnd()
+      val tp = readType()
+      val lazyAnnotTree = readLaterWithOwner(end, rdr => implicit ctx => rdr.readTerm())
+      owner =>
+        Annotation.deferredSymAndTree(tp.typeSymbol)(lazyAnnotTree(owner).complete)
 
     /** Create symbols for the definitions in the statement sequence between
      *  current address and `end`.