Added support for sealed classes, through permitted subclasses attributes.

base/src/proguard/optimize/ChangedCodePrinter.java

@@ -102,6 +102,12 @@ implements   AttributeVisitor
     }
 
 
+    public void visitPermittedSubclassesAttribute(Clazz clazz, PermittedSubclassesAttribute permittedSubclassesAttribute)
+    {
+        attributeVisitor.visitPermittedSubclassesAttribute(clazz, permittedSubclassesAttribute);
+    }
+
+
     public void visitModuleAttribute(Clazz clazz, ModuleAttribute moduleAttribute)
     {
         attributeVisitor.visitModuleAttribute(clazz, moduleAttribute);

base/src/proguard/shrink/ClassShrinker.java

@@ -54,7 +54,7 @@ implements   ClassVisitor,
 
     private       int[]                   constantIndexMap        = new int[ClassEstimates.TYPICAL_CONSTANT_POOL_SIZE];
     private       int[]                   bootstrapMethodIndexMap = new int[ClassEstimates.TYPICAL_CONSTANT_POOL_SIZE];
-    private final MyNestmemberShrinker    nestMemberShrinker      = new MyNestmemberShrinker();
+    private final MyAttributeShrinker     attributeShrinker       = new MyAttributeShrinker();
     private final ConstantPoolRemapper    constantPoolRemapper    = new ConstantPoolRemapper();
     private final BootstrapMethodRemapper bootstrapMethodRemapper = new BootstrapMethodRemapper();
     private final MySignatureCleaner      signatureCleaner        = new MySignatureCleaner();
@@ -127,8 +127,8 @@ implements   ClassVisitor,
                 .visitProgramClass(programClass);
         }
 
-        // Shrink the arrays for nest members.
-        programClass.attributesAccept(nestMemberShrinker);
+        // Shrink the arrays for nest members and permitted subclasses.
+        programClass.attributesAccept(attributeShrinker);
 
         // Shrink the constant pool, also setting up an index map.
         int newConstantPoolCount =
@@ -361,9 +361,10 @@ implements   ClassVisitor,
 
     /**
      * This AttributeVisitor shrinks the nest members in the nest member
+     * attributes and the permitted subclasses in the permitted subclasses
      * attributes that it visits.
      */
-    private class MyNestmemberShrinker
+    private class MyAttributeShrinker
     implements    AttributeVisitor
     {
         public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
@@ -378,6 +379,17 @@ implements   ClassVisitor,
                                          nestMembersAttribute.u2classes,
                                          nestMembersAttribute.u2classesCount);
         }
+
+
+        public void visitPermittedSubclassesAttribute(Clazz clazz, PermittedSubclassesAttribute permittedSubclassesAttribute)
+        {
+            // Shrink the array of nest member indices.
+            // We must do this before the corresponding constants are remapped.
+            permittedSubclassesAttribute.u2classesCount =
+                shrinkConstantIndexArray(((ProgramClass)clazz).constantPool,
+                                         permittedSubclassesAttribute.u2classes,
+                                         permittedSubclassesAttribute.u2classesCount);
+        }
     }
 
 

base/src/proguard/shrink/ClassUsageMarker.java

@@ -949,6 +949,19 @@ implements   ClassVisitor,
     }
 
 
+    public void visitPermittedSubclassesAttribute(Clazz clazz, PermittedSubclassesAttribute permittedSubclassesAttribute)
+    {
+        // Don't mark the attribute and its contents yet. We may mark it later,
+        // in NestUsageMarker.
+        //markAsUsed(permittedSubclassesAttribute);
+
+        //markConstant(clazz, permittedSubclassesAttribute.u2attributeNameIndex);
+
+        // Mark the nest member entries.
+        //permittedSubclassesAttribute.memberClassConstantsAccept(clazz, this);
+    }
+
+
     public void visitModuleAttribute(Clazz clazz, ModuleAttribute moduleAttribute)
     {
         markAsUsed(moduleAttribute);

base/src/proguard/shrink/NestUsageMarker.java

@@ -28,8 +28,8 @@ import proguard.classfile.constant.visitor.ConstantVisitor;
 import proguard.classfile.visitor.ClassVisitor;
 
 /**
- * This AttributeVisitor marks all necessary nest host attributes and nest
- * members attributes that it visits.
+ * This AttributeVisitor marks all necessary nest host attributes, nest
+ * members attributes, and permitted subclasses attributes that it visits.
  *
  * @see UsageMarker
  *
@@ -82,14 +82,14 @@ implements   AttributeVisitor,
 
     public void visitNestMembersAttribute(Clazz clazz, NestMembersAttribute nestMembersAttribute)
     {
-        // Mark the necessary inner classes information.
+        // Mark the necessary nest member information.
         attributeUsed = false;
         nestMembersAttribute.memberClassConstantsAccept(clazz, this);
 
         if (attributeUsed)
         {
-            // We got a positive used flag, so the nest members class is being used.
-            // Mark this attribute as being used as well.
+            // We got a positive used flag, so at least one of the nest members
+            // is being used. Mark this attribute as being used as well.
             classUsageMarker.markAsUsed(nestMembersAttribute);
 
             markConstant(clazz, nestMembersAttribute.u2attributeNameIndex);
@@ -97,6 +97,24 @@ implements   AttributeVisitor,
     }
 
 
+    public void visitPermittedSubclassesAttribute(Clazz clazz, PermittedSubclassesAttribute permittedSubclassesAttribute)
+    {
+        // Mark the necessary permitted subclasses information.
+        attributeUsed = false;
+        permittedSubclassesAttribute.permittedSubclassConstantsAccept(clazz, this);
+
+        if (attributeUsed)
+        {
+            // We got a positive used flag, so at least one of the permitted
+            // subclasses class is being used. Mark this attribute as being
+            // used as well.
+            classUsageMarker.markAsUsed(permittedSubclassesAttribute);
+
+            markConstant(clazz, permittedSubclassesAttribute.u2attributeNameIndex);
+        }
+    }
+
+
     // Implementations for ConstantVisitor.
 
     public void visitClassConstant(Clazz clazz, ClassConstant classConstant)

docs/md/FAQ.md

@@ -69,15 +69,16 @@ Yes, you can. **ProGuard** itself is distributed under the GPL, but this
 doesn't affect the programs that you process. Your code remains yours, and its
 license can remain the same.
 
-## Does ProGuard work with Java 2, 5,..., 14? {: #jdk1.4}
+## Does ProGuard work with Java 2, 5,..., 15? {: #jdk1.4}
 
-Yes, **ProGuard** supports all JDKs from 1.1 up to and including 14. Java 2
+Yes, **ProGuard** supports all JDKs from 1.1 up to and including 15. Java 2
 introduced some small differences in the class file format. Java 5 added
 attributes for generics and for annotations. Java 6 introduced optional
 preverification attributes. Java 7 made preverification obligatory and
 introduced support for dynamic languages. Java 8 added more attributes and
 default methods. Java 9 added support for modules. Java 11 added dynamic
-constants and nest-based access control. Java 14 added records.
+constants and nest-based access control. Java 14 added records. Java 15
+added sealed classes.
 **ProGuard** handles all versions correctly.
 
 ## Does ProGuard work with Java Micro Edition? {: #jme}

docs/md/manual/attributes.md

@@ -47,7 +47,7 @@ attributes. You can keep them with the
 : Specifies the name of the source directory from which the class file was
   compiled.
 
-`Record`
+`Record` <div>(Java 14 or higher)</div>
 : Specifies the components of a record class. Code may access this information
   by reflection.
 
@@ -59,6 +59,10 @@ attributes. You can keep them with the
   referenced in a compiled library. Code may access this information by
   reflection, for instance to derive the simple name of the class.
 
+`PermittedSubclasses` <div>(Java 15 or higher)</div>
+: Specifies the allowed extensions or implementations of sealed classes or
+  interfaces.
+
 `EnclosingMethod`<div>(Java 5 or higher)</div>
 : Specifies the method in which the class was defined. Compilers may need this
   information to find classes referenced in a compiled library. Code may

docs/md/manual/examples.md

@@ -347,8 +347,9 @@ still be used as such, for developing code based on its public API.
 
     -keepparameternames
     -renamesourcefileattribute SourceFile
-    -keepattributes Exceptions,InnerClasses,Signature,Deprecated,
-                    SourceFile,LineNumberTable,*Annotation*,EnclosingMethod
+    -keepattributes Signature,Exceptions,*Annotation*,
+                    InnerClasses,PermittedSubclasses,EnclosingMethod,
+                    Deprecated,SourceFile,LineNumberTable
 
     -keepclasseswithmembernames,includedescriptorclasses class * {
         native <methods>;
@@ -373,16 +374,26 @@ access in the library. Only if there are any other non-public classes or
 methods that are invoked dynamically, they should be specified using
 additional [`-keep`](usage.md#keep) options.
 
+The "Signature" attribute is required to be able to access generic types.
+
 The "Exceptions" attribute has to be preserved, so the compiler knows
 which exceptions methods may throw.
 
+The various "\*Annotations\*" attributes contain any annotations, which
+developers might need to access through reflection.
+
 The "InnerClasses" attribute (or more precisely, its source name part) has to
 be preserved too, for any inner classes that can be referenced from outside
 the library. The `javac` compiler would be unable to find the inner classes
 otherwise.
 
-The "Signature" attribute is required to be able to access generic types when
-compiling in JDK 5.0 and higher.
+The "PermittedSubclasses" attribute defines sealed classes, which developers
+can't extend further.
+
+The "EnclosingMethod" attribute marks classes that are defined inside methods.
+
+The "Deprecated" attribute marks any deprecated classes, fields, or
+methods, which may be useful for developers to know.
 
 The [`-keepparameternames`](usage.md#keepparameternames) option keeps the
 parameter names in the "LocalVariableTable" and "LocalVariableTypeTable"

docs/md/releasenotes.md

@@ -3,6 +3,7 @@
 | Version| Issue    | Module   | Explanation
 |--------|----------|----------|----------------------------------
 | 7.1.x  | PGD-0064 | CORE     | Added support for Java 14 and 15.
+| 7.1.x  | PGD-0064 | CORE     | Added support for sealed classes (permitted subclasses attributes).
 | 7.1.x  | PGD-0064 | CORE     | Added support for record attributes.
 | 7.1.x  | DGD-2390 | CORE     | Fixed storage and alignment of uncompressed zip entries.
 | 7.1.x  | DGD-2338 | CORE     | Fixed processing of constant boolean arrays.

examples/ant/library.xml

@@ -21,13 +21,14 @@
 
     <!-- Keep some useful attributes. -->
 
+    <keepattribute name="Signature" />
     <keepattribute name="Exceptions" />
     <keepattribute name="InnerClasses" />
-    <keepattribute name="Signature" />
+    <keepattribute name="PermittedSubclasses" />
+    <keepattribute name="EnclosingMethod" />
     <keepattribute name="Deprecated" />
     <keepattribute name="SourceFile" />
     <keepattribute name="LineNumberTable" />
-    <keepattribute name="EnclosingMethod" />
 
     <!-- Preserve all public classes, and their public and protected fields
         and methods. -->

examples/gradle/library.gradle

@@ -53,7 +53,7 @@ task ('proguard', type: proguard.gradle.ProGuardTask) {
     printmapping 'out.map'
     keepparameternames
     renamesourcefileattribute 'SourceFile'
-    keepattributes 'Exceptions,InnerClasses,Signature,Deprecated,SourceFile,LineNumberTable,EnclosingMethod'
+    keepattributes 'Signature,Exceptions,InnerClasses,PermittedSubclasses,EnclosingMethod,Deprecated,SourceFile,LineNumberTable'
 
     // Preserve all annotations.
 

examples/standalone/library.pro

@@ -28,8 +28,9 @@
 -printmapping out.map
 -keepparameternames
 -renamesourcefileattribute SourceFile
--keepattributes Exceptions,InnerClasses,Signature,Deprecated,
-                SourceFile,LineNumberTable,EnclosingMethod
+-keepattributes Signature,Exceptions,
+                InnerClasses,PermittedSubclasses,EnclosingMethod,
+                Deprecated,SourceFile,LineNumberTable
 
 # Preserve all annotations.
 
@@ -78,7 +79,7 @@
     java.lang.Object readResolve();
 }
 
-# Your library may contain more items that need to be preserved; 
+# Your library may contain more items that need to be preserved;
 # typically classes that are dynamically created using Class.forName:
 
 # -keep public class com.example.MyClass