Merge pull request #11010 from dotty-staging/fix-#9327

Avoid stackoverflow in associatedFile computation

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Symbols.scala

@@ -429,7 +429,7 @@ object Symbols {
 
     /** The source or class file from which this class was generated, null if not applicable. */
     override def associatedFile(using Context): AbstractFile =
-      if (assocFile != null || this.owner.is(PackageClass) || this.isEffectiveRoot) assocFile
+      if assocFile != null || this.is(Package) || this.owner.is(Package) then assocFile
       else super.associatedFile
 
     private var mySource: SourceFile = NoSource

tests/neg/i9327.scala

@@ -0,0 +1,4 @@
+// fuzzball, gave SO in associatedFile
+package object Foo // error
+type Foo // error
+class Foo(a: Foo)