From 7c64f7f035f0e070478088a640c4c2e4113dc5fa Mon Sep 17 00:00:00 2001
From: Anna Kozlova <anna.kozlova@jetbrains.com>
Date: Mon, 15 Jun 2020 22:01:30 +0200
Subject: [PATCH] java sealed types: forbid non-sealed classes without sealed
 supers (IDEA-243536)

GitOrigin-RevId: ce7b48fc5df80edf0a4efc987a23850aff993f6c
---
 .../codeInsight/daemon/impl/analysis/HighlightUtil.java      | 5 +++++
 .../advHighlightingSealedTypes/SealedTypesBasics.java        | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightUtil.java b/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightUtil.java
index 45a5535097bb..6c1f6c369be9 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightUtil.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightUtil.java
@@ -988,6 +988,11 @@ public class HighlightUtil {
           isAllowed &= !privateOrProtected;
         }
       }
+      if (PsiModifier.NON_SEALED.equals(modifier) && !aClass.hasModifierProperty(PsiModifier.SEALED)) {
+        isAllowed = Arrays.stream(aClass.getSuperTypes())
+          .map(PsiClassType::resolve)
+          .anyMatch(superClass -> superClass != null && superClass.hasModifierProperty(PsiModifier.SEALED));
+      }
     }
     else if (modifierOwner instanceof PsiMethod) {
       PsiMethod method = (PsiMethod)modifierOwner;
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingSealedTypes/SealedTypesBasics.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingSealedTypes/SealedTypesBasics.java
index 43a98903a8d5..58c1bdbcb5fe 100644
--- a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingSealedTypes/SealedTypesBasics.java
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingSealedTypes/SealedTypesBasics.java
@@ -13,3 +13,7 @@ sealed interface IA permits IB, IC {}
 final class IB implements IA {}
 sealed interface IC extends IA {}
 class ICSameFile implements IC {}
+
+sealed interface ID0 {}
+non-sealed interface ID1 extends ID0 {}
+<error descr="Modifier 'non-sealed' not allowed here">non-sealed</error> interface ID extends ID1 {}