From f48cea56e1efb8196da2f54b6aa0e81c2918b67e Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <bas.leijdekkers@jetbrains.com>
Date: Tue, 17 Jun 2025 10:17:02 +0200
Subject: [PATCH] Java: avoid false positive in broken code with cyclic
 inheritance

for "Subclass field hides superclass field" inspection

GitOrigin-RevId: 2da814fb51c92618cf528260c0ee585b894ca65a
---
 .../visibility/FieldHidesSuperclassFieldInspection.java  | 3 ++-
 .../FieldHidesSuperclassField.java                       | 9 +++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/java/java-impl/src/com/siyeh/ig/visibility/FieldHidesSuperclassFieldInspection.java b/java/java-impl/src/com/siyeh/ig/visibility/FieldHidesSuperclassFieldInspection.java
index d0a021a49e7c..96df354d85b0 100644
--- a/java/java-impl/src/com/siyeh/ig/visibility/FieldHidesSuperclassFieldInspection.java
+++ b/java/java-impl/src/com/siyeh/ig/visibility/FieldHidesSuperclassFieldInspection.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2019 Dave Griffith, Bas Leijdekkers
+ * Copyright 2003-2025 Dave Griffith, Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -97,6 +97,7 @@ public final class FieldHidesSuperclassFieldInspection extends BaseInspection {
       }
       PsiClass ancestorClass = aClass.getSuperClass();
       final Set<PsiClass> visitedClasses = new HashSet<>();
+      visitedClasses.add(aClass);
       while (ancestorClass != null) {
         if (!visitedClasses.add(ancestorClass)) {
           return;
diff --git a/java/java-tests/testData/ig/com/siyeh/igtest/visibility/field_hides_superclass_field/FieldHidesSuperclassField.java b/java/java-tests/testData/ig/com/siyeh/igtest/visibility/field_hides_superclass_field/FieldHidesSuperclassField.java
index 5320e6746d44..1edbff4f0e54 100644
--- a/java/java-tests/testData/ig/com/siyeh/igtest/visibility/field_hides_superclass_field/FieldHidesSuperclassField.java
+++ b/java/java-tests/testData/ig/com/siyeh/igtest/visibility/field_hides_superclass_field/FieldHidesSuperclassField.java
@@ -10,4 +10,13 @@ class Sub extends FieldHidesSuperclassField {
 class Sub2 extends FieldHidesSuperclassField {
   String a;
   String <warning descr="Field 's' hides field in superclass">s</warning>;
+}
+<error descr="Cyclic inheritance involving 'A'">class A extends B</error> {
+  String s = "";
+
+  void f() { }
+}
+
+<error descr="Cyclic inheritance involving 'B'">class B extends A</error> {
+  void f() { }
 }
\ No newline at end of file