8347530: Improve error message with invalid permits clauses

Reviewed-by: jlahoda

Author: biboudis

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java

@@ -5475,8 +5475,13 @@ void attribClass(ClassSymbol c) throws CompletionFailure {
                                                         .stream()
                                                         .anyMatch(d -> d.tsym == c);
                             if (!thisIsASuper) {
-                                log.error(TreeInfo.diagnosticPositionFor(subType.tsym, env.tree),
-                                        Errors.InvalidPermitsClause(Fragments.DoesntExtendSealed(subType)));
+                                if(c.isInterface()) {
+                                    log.error(TreeInfo.diagnosticPositionFor(subType.tsym, env.tree),
+                                            Errors.InvalidPermitsClause(Fragments.DoesntImplementSealed(kindName(subType.tsym), subType)));
+                                } else {
+                                    log.error(TreeInfo.diagnosticPositionFor(subType.tsym, env.tree),
+                                            Errors.InvalidPermitsClause(Fragments.DoesntExtendSealed(subType)));
+                                }
                             }
                         }
                     }

src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties

@@ -3957,7 +3957,11 @@ compiler.misc.is.duplicated=\
 
 # 0: type
 compiler.misc.doesnt.extend.sealed=\
-    subclass {0} must extend sealed class
+    class {0} must extend sealed class
+
+# 0: kind name, 1: type
+compiler.misc.doesnt.implement.sealed=\
+    {0} {1} must extend sealed interface
 
 compiler.misc.must.not.be.same.class=\
     illegal self-reference in permits clause

test/langtools/tools/javac/T8347530.java

@@ -0,0 +1,29 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8347530
+ * @summary Improve error message with invalid permits clauses
+ * @compile/fail/ref=T8347530.out -XDrawDiagnostics T8347530.java
+ */
+
+class T8347530 {
+    // sealed interfaces
+    sealed interface A0 permits B0 {}
+    class B0 {}     // class {0} must implement sealed interface
+
+    sealed interface A1 permits B1 {}
+    record B1() {}  // record {0} must implement sealed interface
+
+    sealed interface A2 permits B2 {}
+    enum B2 {}      // enum {0} must implement sealed interface
+
+    sealed interface A3 permits B3 {}
+    interface B3 {} // interface {0} must implement sealed interface
+
+    // sealed classes
+    sealed class C0 permits S0 {}
+    class S0 {}     // class {0} must extend sealed class
+
+    // record cannot extend other classes in general
+    // enums cannot extend other classes in general
+    // interfaces cannot extend other classes in general
+}

test/langtools/tools/javac/T8347530.out

@@ -0,0 +1,6 @@
+T8347530.java:10:33: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.implement.sealed: kindname.class, T8347530.B0)
+T8347530.java:13:33: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.implement.sealed: kindname.record, T8347530.B1)
+T8347530.java:16:33: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.implement.sealed: kindname.enum, T8347530.B2)
+T8347530.java:19:33: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.implement.sealed: kindname.interface, T8347530.B3)
+T8347530.java:23:29: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.extend.sealed: T8347530.S0)
+5 errors

test/langtools/tools/javac/diags/examples/SubtypeDoesntImplementSealed.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+// key: compiler.err.invalid.permits.clause
+// key: compiler.misc.doesnt.implement.sealed
+
+sealed interface A3 permits B3 {}
+interface B3 {}
+

test/langtools/tools/javac/sealed/SealedDiffConfigurationsTest.java

@@ -556,7 +556,7 @@ public void testSameModuleSamePkgNeg2(Path base) throws Exception {
                 .getOutputLines(OutputKind.DIRECT);
 
         List<String> expected = List.of(
-                "Sealed.java:1:66: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.extend.sealed: pkg.Sub2)",
+                "Sealed.java:1:66: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.implement.sealed: kindname.class, pkg.Sub2)",
                 "1 error");
         if (!error.containsAll(expected)) {
             throw new AssertionError("Expected output not found. Found: " + error);

test/langtools/tools/javac/sealed/erroneous_hierarchy/CyclicHierarchyTest.out

@@ -1,3 +1,3 @@
-CyclicHierarchyTest.java:9:37: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.extend.sealed: CyclicHierarchyTest.Add)
+CyclicHierarchyTest.java:9:37: compiler.err.invalid.permits.clause: (compiler.misc.doesnt.implement.sealed: kindname.class, CyclicHierarchyTest.Add)
 CyclicHierarchyTest.java:11:55: compiler.err.invalid.permits.clause: (compiler.misc.must.not.be.same.class)
 2 errors