Fix cycles in classfile parsing

Author: liufengyun

compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala

@@ -619,14 +619,15 @@ class ClassfileParser(
   // invariant: `in` and `ctx` should not be captured inside the result function
   def parseAttributes(sym: Symbol, pt: Type = WildcardType, isVarargs: Boolean = false)(using ctx: Context, in: DataReader): AttributeCompleter = {
     var typeUpdate: Option[Context ?=> Type] = None
-
+    var delayedWork: List[Context ?=> Unit] = Nil
     val res = new AttributeCompleter {
       def complete(tp: Type)(using Context): Type = {
         val newType = if (typeUpdate.isEmpty) tp else typeUpdate.get
         exceptions.foreach { ex =>
           val cls = getClassSymbol(ex.name)
           sym.addAnnotation(ThrowsAnnotation(cls.asClass))
         }
+        delayedWork.foreach(_.apply)
         cook.apply(newType)
       }
     }
@@ -680,10 +681,13 @@ class ClassfileParser(
 
         case tpnme.CodeATTR =>
           in.skip(attrLen)
-          if (sym.owner.isAllOf(Flags.JavaInterface)) {
-            sym.resetFlag(Flags.Deferred)
-            sym.owner.resetFlag(Flags.PureInterface)
-            report.log(s"$sym in ${sym.owner} is a java8+ default method.")
+          // flag test will trigger completion and cycles, thus have to be lazy
+          delayedWork ::= { (using ctx) =>
+            if (sym.owner.isAllOf(Flags.JavaInterface)) {
+              sym.resetFlag(Flags.Deferred)
+              sym.owner.resetFlag(Flags.PureInterface)
+              report.log(s"$sym in ${sym.owner} is a java 8+ default method.")
+            }
           }
 
         case _ =>