[analyzer] Add sealed modifier to ClassOrMixinElementImpl and source visitor.

Add sealed modifier to element builder summaries and to_source_visitor.
Enable sealed_class experiement in tests to test the changes.

Change-Id: I2929a5a38360c73abfcdb26d1e9b786058ea9335
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/272351
Commit-Queue: Kallen Tu <kallentu@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -85,7 +85,7 @@ import 'package:analyzer/src/util/performance/operation_performance.dart';
 /// TODO(scheglov) Clean up the list of implicitly analyzed files.
 class AnalysisDriver implements AnalysisDriverGeneric {
   /// The version of data format, should be incremented on every format change.
-  static const int DATA_VERSION = 250;
+  static const int DATA_VERSION = 251;
 
   /// The number of exception contexts allowed to write. Once this field is
   /// zero, we stop writing any new exception contexts in this process.

pkg/analyzer/lib/src/dart/ast/to_source_visitor.dart

@@ -188,6 +188,7 @@ class ToSourceVisitor implements AstVisitor<void> {
     _visitToken(node.augmentKeyword, suffix: ' ');
     _visitToken(node.abstractKeyword, suffix: ' ');
     _visitToken(node.macroKeyword, suffix: ' ');
+    _visitToken(node.sealedKeyword, suffix: ' ');
     sink.write('class ');
     _visitToken(node.name);
     _visitNode(node.typeParameters);
@@ -205,6 +206,7 @@ class ToSourceVisitor implements AstVisitor<void> {
     _visitToken(node.augmentKeyword, suffix: ' ');
     _visitToken(node.abstractKeyword, suffix: ' ');
     _visitToken(node.macroKeyword, suffix: ' ');
+    _visitToken(node.sealedKeyword, suffix: ' ');
     sink.write('class ');
     _visitToken(node.name);
     _visitNode(node.typeParameters);

pkg/analyzer/lib/src/dart/element/element.dart

@@ -998,6 +998,14 @@ abstract class ClassOrMixinElementImpl extends AbstractClassElementImpl {
     return _interfaces;
   }
 
+  bool get isSealed {
+    return hasModifier(Modifier.SEALED);
+  }
+
+  set isSealed(bool isSealed) {
+    setModifier(Modifier.SEALED, isSealed);
+  }
+
   @override
   bool get isSimplyBounded {
     return hasModifier(Modifier.SIMPLY_BOUNDED);
@@ -4839,24 +4847,27 @@ class Modifier implements Comparable<Modifier> {
 
   static const Modifier PROMOTABLE = Modifier('IS_PROMOTABLE', 20);
 
+  /// Indicates that the modifier 'sealed' was applied to the element.
+  static const Modifier SEALED = Modifier('SEALED', 21);
+
   /// Indicates that the pseudo-modifier 'set' was applied to the element.
-  static const Modifier SETTER = Modifier('SETTER', 21);
+  static const Modifier SETTER = Modifier('SETTER', 22);
 
   /// See [TypeParameterizedElement.isSimplyBounded].
-  static const Modifier SIMPLY_BOUNDED = Modifier('SIMPLY_BOUNDED', 22);
+  static const Modifier SIMPLY_BOUNDED = Modifier('SIMPLY_BOUNDED', 23);
 
   /// Indicates that the modifier 'static' was applied to the element.
-  static const Modifier STATIC = Modifier('STATIC', 23);
+  static const Modifier STATIC = Modifier('STATIC', 24);
 
   /// Indicates that the element does not appear in the source code but was
   /// implicitly created. For example, if a class does not define any
   /// constructors, an implicit zero-argument constructor will be created and it
   /// will be marked as being synthetic.
-  static const Modifier SYNTHETIC = Modifier('SYNTHETIC', 24);
+  static const Modifier SYNTHETIC = Modifier('SYNTHETIC', 25);
 
   /// Indicates that the element was appended to this enclosing element to
   /// simulate temporary the effect of applying augmentation.
-  static const Modifier TEMP_AUGMENTATION = Modifier('TEMP_AUGMENTATION', 25);
+  static const Modifier TEMP_AUGMENTATION = Modifier('TEMP_AUGMENTATION', 26);
 
   static const List<Modifier> values = [
     ABSTRACT,
@@ -4879,6 +4890,7 @@ class Modifier implements Comparable<Modifier> {
     MACRO,
     MIXIN_APPLICATION,
     PROMOTABLE,
+    SEALED,
     SETTER,
     STATIC,
     SIMPLY_BOUNDED,

pkg/analyzer/lib/src/summary2/element_builder.dart

@@ -91,6 +91,7 @@ class ElementBuilder extends ThrowingAstVisitor<void> {
     var element = ClassElementImpl(name, nameToken.offset);
     element.isAbstract = node.abstractKeyword != null;
     element.isMacro = node.macroKeyword != null;
+    element.isSealed = node.sealedKeyword != null;
     element.metadata = _buildAnnotations(node.metadata);
     _setCodeRange(element, node);
     _setDocumentation(element, node);
@@ -124,6 +125,7 @@ class ElementBuilder extends ThrowingAstVisitor<void> {
     var element = ClassElementImpl(name, nameToken.offset);
     element.isAbstract = node.abstractKeyword != null;
     element.isMacro = node.macroKeyword != null;
+    element.isSealed = node.sealedKeyword != null;
     element.isMixinApplication = true;
     element.metadata = _buildAnnotations(node.metadata);
     _setCodeRange(element, node);
@@ -848,6 +850,7 @@ class ElementBuilder extends ThrowingAstVisitor<void> {
     var name = nameToken.lexeme;
 
     var element = MixinElementImpl(name, nameToken.offset);
+    element.isSealed = node.sealedKeyword != null;
     element.metadata = _buildAnnotations(node.metadata);
     _setCodeRange(element, node);
     _setDocumentation(element, node);

pkg/analyzer/lib/src/summary2/element_flags.dart

@@ -10,13 +10,15 @@ class ClassElementFlags {
   static const int _isAbstract = 1 << 0;
   static const int _isMacro = 1 << 1;
   static const int _isMixinApplication = 1 << 2;
-  static const int _isSimplyBounded = 1 << 3;
+  static const int _isSealed = 1 << 3;
+  static const int _isSimplyBounded = 1 << 4;
 
   static void read(SummaryDataReader reader, ClassElementImpl element) {
     var byte = reader.readByte();
     element.isAbstract = (byte & _isAbstract) != 0;
     element.isMacro = (byte & _isMacro) != 0;
     element.isMixinApplication = (byte & _isMixinApplication) != 0;
+    element.isSealed = (byte & _isSealed) != 0;
     element.isSimplyBounded = (byte & _isSimplyBounded) != 0;
   }
 
@@ -25,6 +27,7 @@ class ClassElementFlags {
     result |= element.isAbstract ? _isAbstract : 0;
     result |= element.isMacro ? _isMacro : 0;
     result |= element.isMixinApplication ? _isMixinApplication : 0;
+    result |= element.isSealed ? _isSealed : 0;
     result |= element.isSimplyBounded ? _isSimplyBounded : 0;
     sink.writeByte(result);
   }
@@ -223,15 +226,18 @@ class MethodElementFlags {
 }
 
 class MixinElementFlags {
-  static const int _isSimplyBounded = 1 << 0;
+  static const int _isSealed = 1 << 0;
+  static const int _isSimplyBounded = 1 << 1;
 
   static void read(SummaryDataReader reader, MixinElementImpl element) {
     var byte = reader.readByte();
+    element.isSealed = (byte & _isSealed) != 0;
     element.isSimplyBounded = (byte & _isSimplyBounded) != 0;
   }
 
   static void write(BufferedSink sink, MixinElementImpl element) {
     var result = 0;
+    result |= element.isSealed ? _isSealed : 0;
     result |= element.isSimplyBounded ? _isSimplyBounded : 0;
     sink.writeByte(result);
   }

pkg/analyzer/test/src/dart/ast/to_source_visitor_test.dart

@@ -482,6 +482,16 @@ $code
     _assertSource(code, findNode.classDeclaration(code));
   }
 
+  void test_visitClassDeclaration_sealed() {
+    var findNode = _parseStringToFindNode(r'''
+sealed class A {}
+''');
+    _assertSource(
+      'sealed class A {}',
+      findNode.classDeclaration('class A'),
+    );
+  }
+
   void test_visitClassDeclaration_singleMember() {
     final code = 'class C {var a;}';
     final findNode = _parseStringToFindNode(code);
@@ -595,6 +605,16 @@ $code
     _assertSource(code, findNode.classTypeAlias(code));
   }
 
+  void test_visitClassTypeAlias_sealed() {
+    var findNode = _parseStringToFindNode(r'''
+sealed class A = S with M;
+''');
+    _assertSource(
+      'sealed class A = S with M;',
+      findNode.classTypeAlias('class A'),
+    );
+  }
+
   void test_visitClassTypeAlias_withMetadata() {
     final code = '@deprecated class A = S with M;';
     final findNode = _parseStringToFindNode(code);

pkg/analyzer/test/src/dart/resolution/context_collection_resolution.dart

@@ -325,6 +325,7 @@ class PubPackageResolutionTest extends ContextResolutionTest {
         EnableString.macros,
         EnableString.patterns,
         EnableString.records,
+        EnableString.sealed_class,
       ];
 
   @override

pkg/analyzer/test/src/summary/element_text.dart

@@ -290,12 +290,14 @@ class _ElementWriter {
       if (e is ClassElement) {
         _writeIf(e.isAbstract, 'abstract ');
         _writeIf(e.isMacro, 'macro ');
+        _writeIf(e.isSealed, 'sealed ');
       }
       _writeIf(!e.isSimplyBounded, 'notSimplyBounded ');
 
       if (e is EnumElement) {
         buffer.write('enum ');
       } else if (e is MixinElement) {
+        _writeIf(e.isSealed, 'sealed ');
         buffer.write('mixin ');
       } else {
         buffer.write('class ');
@@ -1085,4 +1087,16 @@ extension on ClassElement {
     final self = this;
     return self is ClassElementImpl && self.isMacro;
   }
+
+  bool get isSealed {
+    final self = this;
+    return self is ClassElementImpl && self.isSealed;
+  }
+}
+
+extension on MixinElement {
+  bool get isSealed {
+    final self = this;
+    return self is MixinElementImpl && self.isSealed;
+  }
 }

pkg/analyzer/test/src/summary/elements_test.dart

@@ -7570,6 +7570,18 @@ library
 ''');
   }
 
+  test_class_sealed() async {
+    var library = await buildLibrary('sealed class C {}');
+    checkElementText(library, r'''
+library
+  definingUnit
+    classes
+      sealed class C @13
+        constructors
+          synthetic @-1
+''');
+  }
+
   test_class_setter_abstract() async {
     var library =
         await buildLibrary('abstract class C { void set x(int value); }');
@@ -9031,6 +9043,35 @@ library
 ''');
   }
 
+  test_classAlias_sealed() async {
+    var library = await buildLibrary('''
+sealed class C = Object with M;
+mixin M {}
+''');
+    checkElementText(library, r'''
+library
+  definingUnit
+    classes
+      sealed class alias C @13
+        supertype: Object
+        mixins
+          M
+        constructors
+          synthetic const @-1
+            constantInitializers
+              SuperConstructorInvocation
+                superKeyword: super @0
+                argumentList: ArgumentList
+                  leftParenthesis: ( @0
+                  rightParenthesis: ) @0
+                staticElement: dart:core::@class::Object::@constructor::new
+    mixins
+      mixin M @38
+        superclassConstraints
+          Object
+''');
+  }
+
   test_classAlias_with_const_constructors() async {
     addSource('$testPackageLibPath/a.dart', r'''
 class Base {
@@ -34207,6 +34248,20 @@ library
 ''');
   }
 
+  test_mixin_sealed() async {
+    var library = await buildLibrary(r'''
+sealed mixin M on A {}
+''');
+    checkElementText(library, r'''
+library
+  definingUnit
+    mixins
+      sealed mixin M @13
+        superclassConstraints
+          Object
+''');
+  }
+
   test_mixin_setter_invokesSuperSelf_getter() async {
     var library = await buildLibrary(r'''
 mixin M on A {