8338981: Access to private classes should be permitted inside the permits clause of the enclosing top-level class

Reviewed-by: vromero, mcimadamore

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Source.java

@@ -262,6 +262,7 @@ public enum Source {
         PRIMITIVE_PATTERNS(JDK23, Fragments.FeaturePrimitivePatterns, DiagKind.PLURAL),
         FLEXIBLE_CONSTRUCTORS(JDK22, Fragments.FeatureFlexibleConstructors, DiagKind.NORMAL),
         MODULE_IMPORTS(JDK23, Fragments.FeatureModuleImports, DiagKind.PLURAL),
+        PRIVATE_MEMBERS_IN_PERMITS_CLAUSE(JDK19),
         ;
 
         enum DiagKind {

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

@@ -92,6 +92,10 @@ public class AttrContext {
      */
     boolean allowProtectedAccess = false;
 
+    /** Are we attributing a permits clause?
+     */
+    boolean isPermitsClause = false;
+
     /** Are arguments to current function applications boxed into an array for varargs?
      */
     Resolve.MethodResolutionPhase pendingResolutionPhase = null;
@@ -149,6 +153,7 @@ public class AttrContext {
         info.preferredTreeForDiagnostics = preferredTreeForDiagnostics;
         info.visitingServiceImplementation = visitingServiceImplementation;
         info.allowProtectedAccess = allowProtectedAccess;
+        info.isPermitsClause = isPermitsClause;
         return info;
     }
 

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

@@ -111,6 +111,7 @@ public class Resolve {
     private final boolean compactMethodDiags;
     private final boolean allowLocalVariableTypeInference;
     private final boolean allowYieldStatement;
+    private final boolean allowPrivateMembersInPermitsClause;
     final EnumSet<VerboseResolutionMode> verboseResolutionMode;
     final boolean dumpMethodReferenceSearchResults;
     final boolean dumpStacktraceOnError;
@@ -147,6 +148,7 @@ public class Resolve {
         Target target = Target.instance(context);
         allowLocalVariableTypeInference = Feature.LOCAL_VARIABLE_TYPE_INFERENCE.allowedInSource(source);
         allowYieldStatement = Feature.SWITCH_EXPRESSION.allowedInSource(source);
+        allowPrivateMembersInPermitsClause = Feature.PRIVATE_MEMBERS_IN_PERMITS_CLAUSE.allowedInSource(source);
         polymorphicSignatureScope = WriteableScope.create(syms.noSymbol);
         allowModules = Feature.MODULES.allowedInSource(source);
         allowRecords = Feature.RECORDS.allowedInSource(source);
@@ -425,7 +427,9 @@ public class Resolve {
                 (env.enclClass.sym == sym.owner // fast special case
                  ||
                  env.enclClass.sym.outermostClass() ==
-                 sym.owner.outermostClass())
+                 sym.owner.outermostClass()
+                 ||
+                 privateMemberInPermitsClauseIfAllowed(env, sym))
                 &&
                 sym.isInheritedIn(site.tsym, types);
         case 0:
@@ -458,6 +462,13 @@ public class Resolve {
             return isAccessible(env, site, checkInner) && notOverriddenIn(site, sym);
         }
     }
+
+    private boolean privateMemberInPermitsClauseIfAllowed(Env<AttrContext> env, Symbol sym) {
+        return allowPrivateMembersInPermitsClause &&
+            env.info.isPermitsClause &&
+            ((JCClassDecl) env.tree).sym.outermostClass() == sym.owner.outermostClass();
+    }
+
     //where
     /* `sym' is accessible only if not overridden by
      * another symbol which is a member of `site'

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

@@ -979,11 +979,17 @@ public class TypeEnter implements Completer {
             if (sym.isPermittedExplicit) {
                 ListBuffer<Symbol> permittedSubtypeSymbols = new ListBuffer<>();
                 List<JCExpression> permittedTrees = tree.permitting;
+                var isPermitsClause = baseEnv.info.isPermitsClause;
+                try {
+                    baseEnv.info.isPermitsClause = true;
                     for (JCExpression permitted : permittedTrees) {
                         Type pt = attr.attribBase(permitted, baseEnv, false, false, false);
                         permittedSubtypeSymbols.append(pt.tsym);
                     }
                     sym.setPermittedSubclasses(permittedSubtypeSymbols.toList());
+                } finally {
+                    baseEnv.info.isPermitsClause = isPermitsClause;
+                }
             }
         }
     }

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

@@ -0,0 +1,182 @@
+/*
+ * Copyright (c) 2024, 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.
+ */
+
+/**
+ * @test
+ * @bug 8338981
+ * @summary Access to private classes should be permitted inside the permits clause of the enclosing top-level class.
+ * @library /tools/lib
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *                     jdk.compiler/com.sun.tools.javac.main
+ *                     jdk.compiler/com.sun.tools.javac.util
+ * @build toolbox.ToolBox toolbox.JavacTask toolbox.Task
+ * @run main PrivateMembersInPermitClause -source 19+
+ */
+import java.nio.file.Path;
+import java.util.Objects;
+import toolbox.Task;
+import java.util.List;
+
+public class PrivateMembersInPermitClause extends toolbox.TestRunner {
+
+    private final toolbox.ToolBox tb;
+
+    public PrivateMembersInPermitClause() {
+        super(System.err);
+        tb = new toolbox.ToolBox();
+    }
+
+    public static void main(String... args) throws Exception {
+        new PrivateMembersInPermitClause().runTests();
+    }
+
+    public void runTests() throws Exception {
+        runTests(_ -> new Object[] {});
+    }
+
+    /**
+     * Tests that a private class in the permits clause compiles successfully.
+     */
+    @Test
+    public void privateClassPermitted() throws Exception {
+        var root = Path.of("src");
+        tb.writeJavaFiles(root,
+            """
+            sealed class S permits S.A {
+                private static final class A extends S {}
+            }
+            """
+        );
+
+        new toolbox.JavacTask(tb)
+            .files(root.resolve("S.java"))
+            .run(toolbox.Task.Expect.SUCCESS);
+    }
+
+    /**
+     * Tests that a private class from another top-level class in the permits clause fails to compile.
+     */
+    @Test
+    public void otherTopLevelPrivateClassFails() throws Exception {
+        var root = Path.of("src");
+        tb.writeJavaFiles(root,
+            """
+            public class S {
+                private static final class A extends S {}
+            }
+            sealed class T permits S.A {
+            }
+            """
+        );
+        var expectedErrors = List.of(
+            "S.java:4:25: compiler.err.report.access: S.A, private, S",
+            "1 error"
+        );
+
+        var compileErrors = new toolbox.JavacTask(tb)
+            .files(root.resolve("S.java"))
+            .options("-XDrawDiagnostics")
+            .run(toolbox.Task.Expect.FAIL)
+            .getOutputLines(Task.OutputKind.DIRECT);
+
+        if (!Objects.equals(compileErrors, expectedErrors)) {
+            throw new AssertionError("Expected errors: " + expectedErrors + ", but got: " + compileErrors);
+        }
+    }
+
+    /**
+     * Tests that a private class in the permits clause of an inner class compiles successfully.
+     */
+    @Test
+    public void privateClassInInnerPermitted() throws Exception {
+        var root = Path.of("src");
+        tb.writeJavaFiles(root,
+            """
+            public sealed class S permits S.T.A {
+                static class T {
+                    private static final class A extends S {}
+                }
+            }
+            """
+        );
+
+        new toolbox.JavacTask(tb)
+            .files(root.resolve("S.java"))
+            .run(toolbox.Task.Expect.SUCCESS);
+    }
+
+    /**
+     * Tests that a private class in the permits clause contained in a sibling private inner class compiles successfully.
+     */
+    @Test
+    public void siblingPrivateClassesPermitted() throws Exception {
+        var root = Path.of("src");
+        tb.writeJavaFiles(root,
+            """
+            public class S {
+                private static class A {
+                    private static class B extends C.D {}
+                }
+                private static class C {
+                    private static class D {}
+                }
+            }
+            """
+        );
+
+        new toolbox.JavacTask(tb)
+            .files(root.resolve("S.java"))
+            .run(toolbox.Task.Expect.SUCCESS);
+    }
+
+    /**
+     * Tests that a private class in the permits clause of a sealed class does not compile when the release is lower than 19.
+     */
+    @Test
+    public void testSourceLowerThan19() throws Exception {
+        var root = Path.of("src");
+        tb.writeJavaFiles(root,
+            """
+            sealed class S permits S.A {
+                private static final class A extends S {}
+            }
+            """
+        );
+
+        var expectedErrors = List.of(
+            "S.java:1:25: compiler.err.report.access: S.A, private, S",
+            "S.java:2:26: compiler.err.cant.inherit.from.sealed: S",
+            "2 errors"
+        );
+
+        var actualOutput = new toolbox.JavacTask(tb)
+            .files(root.resolve("S.java"))
+            .options("--release", "18", "-XDrawDiagnostics")
+            .run(toolbox.Task.Expect.FAIL)
+            .getOutputLines(Task.OutputKind.DIRECT);
+
+        if (!Objects.equals(actualOutput, expectedErrors)) {
+            throw new AssertionError("Expected errors: " + expectedErrors + ", but got: " + actualOutput);
+        }
+    }
+}