8260517: implement Sealed Classes as a standard feature in Java

Co-authored-by: Harold Seigel <hseigel@openjdk.org> Co-authored-by: Vicente Romero <vromero@openjdk.org> Reviewed-by: dholmes, mcimadamore, jlahoda
openjdk · May 20, 2021 · 0fa9223 · 0fa9223 · openjdk-notifier · May 20, 2021
1 parent 31b98e1
commit 0fa9223
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Showing 54 changed files with 169 additions and 393 deletions.
diff --git a/make/langtools/src/classes/build/tools/symbolgenerator/CreateSymbols.java b/make/langtools/src/classes/build/tools/symbolgenerator/CreateSymbols.java
@@ -132,6 +132,7 @@
 import com.sun.tools.classfile.Module_attribute.RequiresEntry;
 import com.sun.tools.classfile.NestHost_attribute;
 import com.sun.tools.classfile.NestMembers_attribute;
+import com.sun.tools.classfile.PermittedSubclasses_attribute;
 import com.sun.tools.classfile.Record_attribute;
 import com.sun.tools.classfile.Record_attribute.ComponentInfo;
 import com.sun.tools.classfile.RuntimeAnnotations_attribute;
@@ -978,6 +979,16 @@ private void addAttributes(ClassHeaderDescription header,
             attributes.put(Attribute.Record,
                            new Record_attribute(attributeString, recordComponents));
         }
+        if (header.isSealed) {
+            int attributeString = addString(constantPool, Attribute.PermittedSubclasses);
+            int[] subclasses = new int[header.permittedSubclasses.size()];
+            int i = 0;
+            for (String intf : header.permittedSubclasses) {
+                subclasses[i++] = addClass(constantPool, intf);
+            }
+            attributes.put(Attribute.PermittedSubclasses,
+                    new PermittedSubclasses_attribute(attributeString, subclasses));
+        }
         addInnerClassesAttribute(header, constantPool, attributes);
     }
 
@@ -2229,6 +2240,16 @@ private boolean readAttribute(ClassFile cf, FeatureDescription feature, Attribut
                 }
                 break;
             }
+            case Attribute.PermittedSubclasses: {
+                assert feature instanceof ClassHeaderDescription;
+                PermittedSubclasses_attribute permittedSubclasses = (PermittedSubclasses_attribute) attr;
+                ClassHeaderDescription chd = (ClassHeaderDescription) feature;
+                chd.permittedSubclasses = Arrays.stream(permittedSubclasses.subtypes)
+                        .mapToObj(i -> getClassName(cf, i))
+                        .collect(Collectors.toList());
+                chd.isSealed = true;
+                break;
+            }
             default:
                 throw new IllegalStateException("Unhandled attribute: " +
                                                 attrName);
@@ -3077,6 +3098,8 @@ static class ClassHeaderDescription extends HeaderDescription {
         List<String> nestMembers;
         boolean isRecord;
         List<RecordComponentDescription> recordComponents;
+        boolean isSealed;
+        List<String> permittedSubclasses;
 
         @Override
         public int hashCode() {
@@ -3087,6 +3110,8 @@ public int hashCode() {
             hash = 17 * hash + Objects.hashCode(this.nestMembers);
             hash = 17 * hash + Objects.hashCode(this.isRecord);
             hash = 17 * hash + Objects.hashCode(this.recordComponents);
+            hash = 17 * hash + Objects.hashCode(this.isSealed);
+            hash = 17 * hash + Objects.hashCode(this.permittedSubclasses);
             return hash;
         }
 
@@ -3117,6 +3142,12 @@ public boolean equals(Object obj) {
             if (!listEquals(this.recordComponents, other.recordComponents)) {
                 return false;
             }
+            if (this.isSealed != other.isSealed) {
+                return false;
+            }
+            if (!listEquals(this.permittedSubclasses, other.permittedSubclasses)) {
+                return false;
+            }
             return true;
         }
 
@@ -3137,6 +3168,9 @@ public void write(Appendable output, String baselineVersion, String version) thr
             if (isRecord) {
                 output.append(" record true");
             }
+            if (isSealed) {
+                output.append(" sealed true");
+            }
             writeAttributes(output);
             output.append("\n");
             writeRecordComponents(output, baselineVersion, version);
@@ -3163,6 +3197,11 @@ public boolean read(LineBasedReader reader) throws IOException {
                 readRecordComponents(reader);
             }
             readInnerClasses(reader);
+            isSealed = reader.attributes.containsKey("permittedSubclasses");
+            if (isSealed) {
+                String subclassesList = reader.attributes.get("permittedSubclasses");
+                permittedSubclasses = deserializeList(subclassesList);
+            }
 
             return true;
         }

diff --git a/src/hotspot/share/classfile/classFileParser.cpp b/src/hotspot/share/classfile/classFileParser.cpp
@@ -3532,12 +3532,6 @@ void ClassFileParser::parse_classfile_bootstrap_methods_attribute(const ClassFil
                      CHECK);
 }
 
-bool ClassFileParser::supports_sealed_types() {
-  return _major_version == JVM_CLASSFILE_MAJOR_VERSION &&
-         _minor_version == JAVA_PREVIEW_MINOR_VERSION &&
-         Arguments::enable_preview();
-}
-
 void ClassFileParser::parse_classfile_attributes(const ClassFileStream* const cfs,
                                                  ConstantPool* cp,
                  ClassFileParser::ClassAnnotationCollector* parsed_annotations,
@@ -3794,8 +3788,8 @@ void ClassFileParser::parse_classfile_attributes(const ClassFileStream* const cf
             parsed_record_attribute = true;
             record_attribute_start = cfs->current();
             record_attribute_length = attribute_length;
-          } else if (tag == vmSymbols::tag_permitted_subclasses()) {
-            if (supports_sealed_types()) {
+          } else if (_major_version >= JAVA_17_VERSION) {
+            if (tag == vmSymbols::tag_permitted_subclasses()) {
               if (parsed_permitted_subclasses_attribute) {
                 classfile_parse_error("Multiple PermittedSubclasses attributes in class file %s", CHECK);
                 return;
@@ -3810,7 +3804,7 @@ void ClassFileParser::parse_classfile_attributes(const ClassFileStream* const cf
               permitted_subclasses_attribute_length = attribute_length;
             }
           }
-          // Skip attribute_length for any attribute where major_verson >= JAVA_16_VERSION
+          // Skip attribute_length for any attribute where major_verson >= JAVA_17_VERSION
           cfs->skip_u1(attribute_length, CHECK);
         } else {
           // Unknown attribute

diff --git a/src/hotspot/share/classfile/classFileParser.hpp b/src/hotspot/share/classfile/classFileParser.hpp
@@ -333,9 +333,6 @@ class ClassFileParser {
                                       const u1* const record_attribute_start,
                                       TRAPS);
 
-  bool supports_sealed_types();
-  bool supports_records();
-
   void parse_classfile_attributes(const ClassFileStream* const cfs,
                                   ConstantPool* cp,
                                   ClassAnnotationCollector* parsed_annotations,

diff --git a/src/hotspot/share/include/jvm.h b/src/hotspot/share/include/jvm.h
@@ -606,15 +606,15 @@ JVM_GetNestHost(JNIEnv *env, jclass current);
 JNIEXPORT jobjectArray JNICALL
 JVM_GetNestMembers(JNIEnv *env, jclass current);
 
-/* Records - since JDK 14 */
+/* Records - since JDK 16 */
 
 JNIEXPORT jboolean JNICALL
 JVM_IsRecord(JNIEnv *env, jclass cls);
 
 JNIEXPORT jobjectArray JNICALL
 JVM_GetRecordComponents(JNIEnv *env, jclass ofClass);
 
-/* Sealed types - since JDK 15 */
+/* Sealed classes - since JDK 17 */
 
 JNIEXPORT jobjectArray JNICALL
 JVM_GetPermittedSubclasses(JNIEnv *env, jclass current);

diff --git a/src/java.base/share/classes/java/lang/Class.java b/src/java.base/share/classes/java/lang/Class.java
@@ -4475,9 +4475,8 @@ public Optional<ClassDesc> describeConstable() {
      *
      * @jls 8.1 Class Declarations
      * @jls 9.1 Interface Declarations
-     * @since 15
+     * @since 17
      */
-    @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.SEALED_CLASSES, reflective=true)
     @CallerSensitive
     public Class<?>[] getPermittedSubclasses() {
         Class<?>[] subClasses;
@@ -4524,14 +4523,13 @@ private boolean isDirectSubType(Class<?> c) {
      * subclasses; {@link #getPermittedSubclasses()} returns a non-null but
      * possibly empty value for a sealed class or interface.
      *
-     * @return {@code true} if and only if this {@code Class} object represents a sealed class or interface.
+     * @return {@code true} if and only if this {@code Class} object represents
+     * a sealed class or interface.
      *
      * @jls 8.1 Class Declarations
      * @jls 9.1 Interface Declarations
-     * @since 15
+     * @since 17
      */
-    @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.SEALED_CLASSES, reflective=true)
-    @SuppressWarnings("preview")
     public boolean isSealed() {
         if (isArray() || isPrimitive()) {
             return false;

diff --git a/src/java.base/share/classes/jdk/internal/javac/PreviewFeature.java b/src/java.base/share/classes/jdk/internal/javac/PreviewFeature.java
@@ -54,6 +54,9 @@
     public boolean reflective() default false;
 
     public enum Feature {
+        /*
+         * This one can only be removed after JDK 17
+         */
         SEALED_CLASSES,
         /**
          * A key for testing.

diff --git a/src/jdk.compiler/share/classes/com/sun/source/tree/ClassTree.java b/src/jdk.compiler/share/classes/com/sun/source/tree/ClassTree.java
@@ -93,10 +93,8 @@ public interface ClassTree extends StatementTree {
      *
      * @return the subclasses
      *
-     * @since 15
+     * @since 17
      */
-    @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.SEALED_CLASSES,
-                                       reflective=true)
     default List<? extends Tree> getPermitsClause() {
         return List.of();
     }

diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Preview.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Preview.java
@@ -183,8 +183,6 @@ public boolean isEnabled() {
      */
     public boolean isPreview(Feature feature) {
         return switch (feature) {
-            case SEALED_CLASSES -> true;
-
             //Note: this is a backdoor which allows to optionally treat all features as 'preview' (for testing).
             //When real preview features will be added, this method can be implemented to return 'true'
             //for those selected features, and 'false' for all the others.
@@ -224,9 +222,7 @@ public Error disabledError(JavaFileObject classfile, int majorVersion) {
      * @return true iff sym has been declared using a preview language feature
      */
     public boolean declaredUsingPreviewFeature(Symbol sym) {
-        return ((sym.flags() & RECORD) != 0 && isPreview(Feature.RECORDS)) ||
-               ((sym.flags() & SEALED) != 0 && isPreview(Feature.SEALED_CLASSES)) ||
-               ((sym.flags() & NON_SEALED) != 0 && isPreview(Feature.SEALED_CLASSES));
+        return false;
     }
 
     /**

diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java
@@ -161,8 +161,7 @@ protected Check(Context context) {
         deferredLintHandler = DeferredLintHandler.instance(context);
 
         allowRecords = Feature.RECORDS.allowedInSource(source);
-        allowSealed = (!preview.isPreview(Feature.SEALED_CLASSES) || preview.isEnabled()) &&
-                Feature.SEALED_CLASSES.allowedInSource(source);
+        allowSealed = Feature.SEALED_CLASSES.allowedInSource(source);
     }
 
     /** Character for synthetic names

diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassReader.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassReader.java
@@ -278,8 +278,7 @@ protected ClassReader(Context context) {
         preview = Preview.instance(context);
         allowModules     = Feature.MODULES.allowedInSource(source);
         allowRecords = Feature.RECORDS.allowedInSource(source);
-        allowSealedTypes = (!preview.isPreview(Feature.SEALED_CLASSES) || preview.isEnabled()) &&
-                Feature.SEALED_CLASSES.allowedInSource(source);
+        allowSealedTypes = Feature.SEALED_CLASSES.allowedInSource(source);
 
         saveParameterNames = options.isSet(PARAMETERS);
 

diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java
@@ -186,8 +186,7 @@ protected JavacParser(ParserFactory fac,
         this.allowYieldStatement = (!preview.isPreview(Feature.SWITCH_EXPRESSION) || preview.isEnabled()) &&
                 Feature.SWITCH_EXPRESSION.allowedInSource(source);
         this.allowRecords = Feature.RECORDS.allowedInSource(source);
-        this.allowSealedTypes = (!preview.isPreview(Feature.SEALED_CLASSES) || preview.isEnabled()) &&
-                Feature.SEALED_CLASSES.allowedInSource(source);
+        this.allowSealedTypes = Feature.SEALED_CLASSES.allowedInSource(source);
     }
 
     protected AbstractEndPosTable newEndPosTable(boolean keepEndPositions) {

diff --git a/test/hotspot/jtreg/runtime/modules/SealedInterfaceModuleTest.java b/test/hotspot/jtreg/runtime/modules/SealedInterfaceModuleTest.java
@@ -27,11 +27,11 @@
  * @modules java.base/jdk.internal.misc
  * @library /test/lib ..
  * @compile sealedP1/SuperInterface.jcod
- * @compile --enable-preview --source ${jdk.version} sealedP1/C1.java sealedP2/C2.java sealedP3/C3.java
+ * @compile sealedP1/C1.java sealedP2/C2.java sealedP3/C3.java
  * @build sun.hotspot.WhiteBox
  * @compile/module=java.base java/lang/ModuleHelper.java
  * @run driver jdk.test.lib.helpers.ClassFileInstaller sun.hotspot.WhiteBox
- * @run main/othervm -Xbootclasspath/a:. --enable-preview -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI SealedInterfaceModuleTest
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI SealedInterfaceModuleTest
  */
 
 public class SealedInterfaceModuleTest {

diff --git a/test/hotspot/jtreg/runtime/modules/SealedModuleTest.java b/test/hotspot/jtreg/runtime/modules/SealedModuleTest.java
@@ -27,11 +27,11 @@
  * @modules java.base/jdk.internal.misc
  * @library /test/lib ..
  * @compile sealedP1/SuperClass.jcod
- * @compile --enable-preview --source ${jdk.version} sealedP1/C1.java sealedP2/C2.java sealedP3/C3.java
+ * @compile sealedP1/C1.java sealedP2/C2.java sealedP3/C3.java
  * @build sun.hotspot.WhiteBox
  * @compile/module=java.base java/lang/ModuleHelper.java
  * @run driver jdk.test.lib.helpers.ClassFileInstaller sun.hotspot.WhiteBox
- * @run main/othervm -Xbootclasspath/a:. --enable-preview -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI SealedModuleTest
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI SealedModuleTest
  */
 
 public class SealedModuleTest {

diff --git a/test/hotspot/jtreg/runtime/modules/sealedP1/SuperClass.jcod b/test/hotspot/jtreg/runtime/modules/sealedP1/SuperClass.jcod
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2021, 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
@@ -32,7 +32,7 @@
 
 class sealedP1/SuperClass {
   0xCAFEBABE;
-  65535; // minor version
+  0; // minor version
   61; // version
   [20] { // Constant Pool
     ; // first element is empty

diff --git a/test/hotspot/jtreg/runtime/modules/sealedP1/SuperInterface.jcod b/test/hotspot/jtreg/runtime/modules/sealedP1/SuperInterface.jcod
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2021, 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
@@ -32,7 +32,7 @@
 //
 class sealedP1/SuperInterface {
   0xCAFEBABE;
-  65535; // minor version
+  0; // minor version
   61; // version
   [14] { // Constant Pool
     ; // first element is empty

diff --git a/test/hotspot/jtreg/runtime/sealedClasses/AbstractSealedTest.java b/test/hotspot/jtreg/runtime/sealedClasses/AbstractSealedTest.java