Add doc comments

Author: odersky

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

@@ -70,6 +70,10 @@ trait TypeAssigner {
     case ex: StaleSymbol => false
   }
 
+  /** If `tpe` is a named type, a normalized version of it that is accessible
+   *  in the current context, or `NoType` if this is not possible.
+   *  Other types are returned unchanged.
+   */
   def accessibleType(tpe: Type, superAccess: Boolean)(using Context): Type =
     tpe match
       case tpe: NamedType =>
@@ -88,6 +92,7 @@ trait TypeAssigner {
           else NoType
       case tpe => tpe
 
+  /** Try to make `tpe` accessible, emit error if not possible */
   def ensureAccessible(tpe: Type, superAccess: Boolean, pos: SrcPos)(using Context): Type =
     val tpe1 = accessibleType(tpe, superAccess)
     if tpe1.exists then tpe1