clarify comment about inlineBodyCache

Author: bishabosha

compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala

@@ -152,7 +152,9 @@ private class ExtractAPICollector(using Context) extends ThunkHolder {
    */
   private val seenInlineCache = mutable.HashSet.empty[Symbol]
 
-  /** This cache is optional, it avoids recomputing hashes of inline "Body" annotations. */
+  /** This cache is optional, it avoids recomputing hashes of inline "Body" annotations,
+   *  e.g. when a concrete inline method is inherited by a subclass.
+   */
   private val inlineBodyCache = mutable.HashMap.empty[Symbol, Int]
 
   private val allNonLocalClassesInSrc = new mutable.HashSet[xsbti.api.ClassLike]
@@ -658,6 +660,7 @@ private class ExtractAPICollector(using Context) extends ThunkHolder {
       // FIXME: The API of a class we send to Zinc includes the signatures of
       // inherited methods, which means that we repeatedly compute the hash of
       // an inline def in every class that extends its owner. To avoid this we
+      // currently cache it in `inlineBodyCache`. Alternatively, we
       // could store the hash as an annotation when pickling an inline def
       // and retrieve it here instead of computing it on the fly.