[GitHub] [groovy] sonatype-lift[bot] commented on a change in pull request #1606: GROOVY-10148: Groovy should not allow classes to extend sealed Java c…

[GitBox <gi...@apache.org>]

sonatype-lift[bot] commented on a change in pull request #1606:
URL: https://github.com/apache/groovy/pull/1606#discussion_r680271839



##########
File path: src/main/java/org/codehaus/groovy/classgen/ClassCompletionVerifier.java
##########
@@ -309,23 +313,79 @@ private void checkAbstractDeclaration(MethodNode methodNode) {
                 methodNode.getTypeDescriptor() + "' must not be abstract.", methodNode);
     }
 
-    private void checkClassForOverwritingFinal(ClassNode cn) {
+    private void checkClassForExtendingFinalOrSealed(ClassNode cn) {
+        boolean sealed = Boolean.TRUE.equals(cn.getNodeMetaData(Sealed.class));
+        if (sealed && cn.getPermittedSubclasses().isEmpty()) {
+            addError("Sealed " + getDescription(cn) + " has no explicit or implicit permitted classes.", cn);
+            return;
+        }
+        boolean isFinal = isFinal(cn.getModifiers());
+        if (sealed && isFinal) {
+            addError("The " + getDescription(cn) + " cannot be both final and sealed.", cn);
+            return;
+        }
+        boolean nonSealed = Boolean.TRUE.equals(cn.getNodeMetaData(NonSealed.class));
         ClassNode superCN = cn.getSuperClass();
-        if (superCN == null) return;
-        if (!isFinal(superCN.getModifiers())) return;
-        String msg = "You are not allowed to overwrite the final " + getDescription(superCN) + ".";
-        addError(msg, cn);
+        boolean sealedSuper = superCN != null && superCN.isSealed();
+        boolean sealedInterface = Arrays.stream(cn.getInterfaces()).anyMatch(ClassNode::isSealed);
+        if (nonSealed && !(sealedSuper || sealedInterface)) {
+            addError("The " + getDescription(cn) + " cannot be non-sealed as it has no sealed parent.", cn);
+            return;
+        }
+        if (sealedSuper || sealedInterface) {
+            if (sealed && nonSealed) {
+                addError("The " + getDescription(cn) + " cannot be both sealed and non-sealed.", cn);
+                return;
+            }
+            if (isFinal && nonSealed) {
+                addError("The " + getDescription(cn) + " cannot be both final and non-sealed.", cn);
+                return;
+            }
+            if (sealedSuper) {
+                checkSealedParent(cn, superCN, isFinal, nonSealed);
+            }
+            if (sealedInterface) {
+                for (ClassNode candidate : cn.getInterfaces()) {
+                    if (candidate.isSealed()) {
+                        checkSealedParent(cn, candidate, isFinal, nonSealed);
+                    }
+                }
+            }
+        }
+        if (superCN == null || !isFinal(superCN.getModifiers())) return;
+        addError("You are not allowed to extend the final " + getDescription(superCN) + ".", cn);
+    }
+
+    private void checkSealedParent(ClassNode cn, ClassNode parent, boolean isFinal, boolean nonSealed) {
+        boolean found = false;
+        for (ClassNode permitted : parent.getPermittedSubclasses()) {
+            if (permitted.equals(cn)) {
+                found = true;
+                break;
+            }
+        }
+        if (!found) {
+            addError("The " + getDescription(cn) + " is not a permitted subclass of the sealed " + getDescription(parent) + ".", cn);
+            return;
+        }
+        boolean explicitlyMarked = nonSealed || cn.isSealed() || isFinal;
+        if (!explicitlyMarked) {
+            addError("The " + getDescription(cn) + " being a child of sealed " + getDescription(parent) + " must be marked final, sealed, or non-sealed.", cn);
+        }
     }
 
     private void checkImplementsAndExtends(ClassNode node) {
-        ClassNode cn = node.getSuperClass();
-        if (cn.isInterface() && !node.isInterface()) {
-            addError("You are not allowed to extend the " + getDescription(cn) + ", use implements instead.", node);
+        ClassNode sn = node.getSuperClass();
+        if (sn.isInterface() && !node.isInterface()) {

Review comment:
       *NULL_DEREFERENCE:*  object `sn` last assigned on line 378 could be null and is dereferenced at line 379.
   (at-me [in a reply](https://help.sonatype.com/lift) with `help` or `ignore`)




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