Add documentation for new field.

Author: q-ata

compiler/src/dotty/tools/dotc/transform/init/Cache.scala

@@ -75,6 +75,10 @@ class Cache[Config, Res]:
    */
   protected var changed: Boolean = false
 
+  /** Whether any value in the cache was accessed after being added.
+  *   If no cached values are used after they are added for the first time
+  *   then another iteration of analysis is not needed.
+  */
   protected var cacheUsed: Boolean = false
 
   /** Used to avoid allocation, its state does not matter */

compiler/src/dotty/tools/dotc/transform/init/Semantic.scala

@@ -1137,7 +1137,7 @@ object Semantic:
   def checkClasses(classes: List[ClassSymbol])(using Context): Unit =
     given Cache.Data()
     for classSym <- classes if isConcreteClass(classSym) do
-      total += checkClass(classSym)
+      checkClass(classSym)
 
 // ----- Semantic definition --------------------------------
   type ArgInfo = TraceValue[Value]