[parser] Declaring constructors - Parse primary constructor this body.

Added two listener calls `beginPrimaryConstructorBody` and
`endPrimaryConstructorBody` for parsing the `this` body.
No AST implementation has been done, only parsing.

Bug: https://github.com/dart-lang/sdk/issues/61699
Change-Id: I6aaf621bb3e67bfe00efe32de8097ca1e5048afb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/459901
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Kallen Tu <kallentu@google.com>

pkg/_fe_analyzer_shared/lib/src/parser/forwarding_listener.dart

@@ -2669,6 +2669,24 @@ class ForwardingListener implements Listener {
   void endConstDotShorthand(Token token) {
     listener?.beginConstDotShorthand(token);
   }
+
+  @override
+  void beginPrimaryConstructorBody(Token token) {
+    listener?.beginPrimaryConstructorBody(token);
+  }
+
+  @override
+  void endPrimaryConstructorBody(
+    Token beginToken,
+    Token? beginInitializers,
+    Token endToken,
+  ) {
+    listener?.endPrimaryConstructorBody(
+      beginToken,
+      beginInitializers,
+      endToken,
+    );
+  }
 }
 
 class NullListener extends ForwardingListener {

pkg/_fe_analyzer_shared/lib/src/parser/listener.dart

@@ -356,6 +356,21 @@ abstract class Listener implements UnescapeErrorListener {
     bool forExtensionType,
   ) {}
 
+  void beginPrimaryConstructorBody(Token token) {}
+
+  // Handles the `this` body block for a primary constructor. Substructures:
+  /// - metadata
+  /// - initializers
+  /// - async marker
+  /// - body
+  void endPrimaryConstructorBody(
+    Token beginToken,
+    Token? beginInitializers,
+    Token endToken,
+  ) {
+    logEvent("endPrimaryConstructorBody");
+  }
+
   void beginCombinators(Token token) {}
 
   void endCombinators(int count) {

pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart

@@ -3715,6 +3715,24 @@ class Parser {
     return token;
   }
 
+  Token parsePrimaryConstructorBody(Token token) {
+    Token beginToken = token;
+    listener.beginPrimaryConstructorBody(token);
+
+    Token? beforeInitializers = token;
+    token = parseInitializersOpt(beforeInitializers);
+
+    token = parseAsyncModifierOpt(token);
+    token = parseFunctionBody(
+      token,
+      /* ofFunctionExpression = */ false,
+      /* allowAbstract = */ inPlainSync,
+    );
+
+    listener.endPrimaryConstructorBody(beginToken, beforeInitializers, token);
+    return token;
+  }
+
   /// Parses an extension type declaration after
   ///
   ///    'extension' 'type'
@@ -5361,6 +5379,22 @@ class Parser {
           return token;
         }
         // Fall through to continue parsing `operator` as an identifier.
+      } else if (identical(value, 'this')) {
+        Token next2 = next.next!;
+        if (next2.isA(TokenType.COLON) ||
+            next2.isA(TokenType.SEMICOLON) ||
+            next2.isA(TokenType.OPEN_CURLY_BRACKET)) {
+          if (!_isDeclaringConstructorsFeatureEnabled) {
+            reportExperimentNotEnabled(
+              ExperimentalFlag.declaringConstructors,
+              next,
+              next,
+            );
+          }
+          token = parsePrimaryConstructorBody(next);
+          listener.endMember();
+          return token;
+        }
       } else if (!next.isIdentifier ||
           (identical(value, 'typedef') &&
               token == beforeStart &&

pkg/analyzer/lib/src/fasta/ast_builder.dart

@@ -617,6 +617,11 @@ class AstBuilder extends StackListener {
     debugEvent("PrimaryConstructor");
   }
 
+  @override
+  void beginPrimaryConstructorBody(Token beginToken) {
+    debugEvent("PrimaryConstructorBody");
+  }
+
   @override
   void beginSwitchCaseWhenClause(Token when) {
     debugEvent("PatternSwitchCaseGuard");
@@ -3168,6 +3173,23 @@ class AstBuilder extends StackListener {
     }
   }
 
+  @override
+  void endPrimaryConstructorBody(
+    Token beginToken,
+    Token? beginInitializers,
+    Token endToken,
+  ) {
+    // TODO(declaring-constructors): Implement primary constructor body.
+    // ignore: unused_local_variable
+    var bodyObject = pop();
+    // ignore: unused_local_variable
+    var initializers = (pop() as List<ConstructorInitializerImpl>?) ?? const [];
+    // ignore: unused_local_variable
+    var separator = pop() as Token?;
+    // ignore: unused_local_variable
+    var metadata = pop() as List<AnnotationImpl>?;
+  }
+
   @override
   void endRecordLiteral(Token leftParenthesis, int count, Token? constKeyword) {
     debugEvent("RecordLiteral");

pkg/front_end/lib/src/source/diet_listener.dart

@@ -1213,6 +1213,22 @@ class DietListener extends StackListenerImpl {
     _memberScope = outermostScope;
   }
 
+  @override
+  // Coverage-ignore(suite): Not run.
+  void endPrimaryConstructorBody(
+    Token beginToken,
+    Token? beginInitializers,
+    Token endToken,
+  ) {
+    debugEvent("endPrimaryConstructorBody");
+    assert(
+      checkState(beginToken, [/* metadata token */ ValueKinds.TokenOrNull]),
+    );
+    // TODO(declaring-constructors): Implement primary constructor body.
+    pop() as Token?;
+    checkEmpty(beginToken.charOffset);
+  }
+
   @override
   void endExtensionTypeDeclaration(
     Token beginToken,

pkg/front_end/lib/src/source/outline_builder.dart

@@ -1960,6 +1960,31 @@ class OutlineBuilder extends StackListenerImpl {
     );
   }
 
+  @override
+  // Coverage-ignore(suite): Not run.
+  void endPrimaryConstructorBody(
+    Token beginToken,
+    Token? beginInitializers,
+    Token endToken,
+  ) {
+    debugEvent("endPrimaryConstructorBody");
+    assert(
+      checkState(beginToken, [
+        ValueKinds.MethodBody,
+        ValueKinds.AsyncModifier,
+        ValueKinds.MetadataListOrNull,
+      ]),
+    );
+
+    // TODO(declaring-constructors): Implement primary constructor body.
+    // ignore: unused_local_variable
+    MethodBody bodyKind = pop() as MethodBody;
+    // ignore: unused_local_variable
+    AsyncMarker asyncModifier = pop() as AsyncMarker;
+    // ignore: unused_local_variable
+    List<MetadataBuilder>? metadata = pop() as List<MetadataBuilder>?;
+  }
+
   @override
   void beginTopLevelMethod(
     Token lastConsumed,

pkg/front_end/lib/src/util/parser_ast.dart

@@ -1533,6 +1533,18 @@ extension MemberExtension on MemberEnd {
     if (child is EnumFactoryMethodEnd) return child;
     throw "Not found";
   }
+
+  bool isPrimaryConstructorBody() {
+    ParserAstNode child = children![1];
+    if (child is PrimaryConstructorBodyEnd) return true;
+    return false;
+  }
+
+  PrimaryConstructorBodyEnd getPrimaryConstructorBody() {
+    ParserAstNode child = children![1];
+    if (child is PrimaryConstructorBodyEnd) return child;
+    throw "Not found";
+  }
 }
 
 // Coverage-ignore(suite): Not run.

pkg/front_end/lib/src/util/parser_ast_helper.dart

@@ -548,6 +548,30 @@ abstract class AbstractParserAstListener implements Listener {
     seen(data);
   }
 
+  @override
+  void beginPrimaryConstructorBody(Token token) {
+    PrimaryConstructorBodyBegin data = new PrimaryConstructorBodyBegin(
+      ParserAstType.BEGIN,
+      token: token,
+    );
+    seen(data);
+  }
+
+  @override
+  void endPrimaryConstructorBody(
+    Token beginToken,
+    Token? beginInitializers,
+    Token endToken,
+  ) {
+    PrimaryConstructorBodyEnd data = new PrimaryConstructorBodyEnd(
+      ParserAstType.END,
+      beginToken: beginToken,
+      beginInitializers: beginInitializers,
+      endToken: endToken,
+    );
+    seen(data);
+  }
+
   @override
   void beginCombinators(Token token) {
     CombinatorsBegin data = new CombinatorsBegin(
@@ -5082,6 +5106,46 @@ class NoPrimaryConstructorHandle extends ParserAstNode {
   R accept<R>(ParserAstVisitor<R> v) => v.visitNoPrimaryConstructorHandle(this);
 }
 
+class PrimaryConstructorBodyBegin extends ParserAstNode {
+  final Token token;
+
+  PrimaryConstructorBodyBegin(ParserAstType type, {required this.token})
+    : super("PrimaryConstructorBody", type);
+
+  @override
+  Map<String, Object?> get deprecatedArguments => {"token": token};
+
+  @override
+  R accept<R>(ParserAstVisitor<R> v) =>
+      v.visitPrimaryConstructorBodyBegin(this);
+}
+
+class PrimaryConstructorBodyEnd extends ParserAstNode
+    implements BeginAndEndTokenParserAstNode {
+  @override
+  final Token beginToken;
+  final Token? beginInitializers;
+  @override
+  final Token endToken;
+
+  PrimaryConstructorBodyEnd(
+    ParserAstType type, {
+    required this.beginToken,
+    this.beginInitializers,
+    required this.endToken,
+  }) : super("PrimaryConstructorBody", type);
+
+  @override
+  Map<String, Object?> get deprecatedArguments => {
+    "beginToken": beginToken,
+    "beginInitializers": beginInitializers,
+    "endToken": endToken,
+  };
+
+  @override
+  R accept<R>(ParserAstVisitor<R> v) => v.visitPrimaryConstructorBodyEnd(this);
+}
+
 class CombinatorsBegin extends ParserAstNode {
   final Token token;
 
@@ -11379,6 +11443,8 @@ abstract class ParserAstVisitor<R> {
   R visitPrimaryConstructorBegin(PrimaryConstructorBegin node);
   R visitPrimaryConstructorEnd(PrimaryConstructorEnd node);
   R visitNoPrimaryConstructorHandle(NoPrimaryConstructorHandle node);
+  R visitPrimaryConstructorBodyBegin(PrimaryConstructorBodyBegin node);
+  R visitPrimaryConstructorBodyEnd(PrimaryConstructorBodyEnd node);
   R visitCombinatorsBegin(CombinatorsBegin node);
   R visitCombinatorsEnd(CombinatorsEnd node);
   R visitCompilationUnitBegin(CompilationUnitBegin node);
@@ -11917,6 +11983,14 @@ class RecursiveParserAstVisitor implements ParserAstVisitor<void> {
   void visitNoPrimaryConstructorHandle(NoPrimaryConstructorHandle node) =>
       node.visitChildren(this);
 
+  @override
+  void visitPrimaryConstructorBodyBegin(PrimaryConstructorBodyBegin node) =>
+      node.visitChildren(this);
+
+  @override
+  void visitPrimaryConstructorBodyEnd(PrimaryConstructorBodyEnd node) =>
+      node.visitChildren(this);
+
   @override
   void visitCombinatorsBegin(CombinatorsBegin node) => node.visitChildren(this);
 
@@ -13384,6 +13458,15 @@ class RecursiveParserAstVisitorWithDefaultNodeAsync
     NoPrimaryConstructorHandle node,
   ) => defaultNode(node);
 
+  @override
+  Future<void> visitPrimaryConstructorBodyBegin(
+    PrimaryConstructorBodyBegin node,
+  ) => defaultNode(node);
+
+  @override
+  Future<void> visitPrimaryConstructorBodyEnd(PrimaryConstructorBodyEnd node) =>
+      defaultNode(node);
+
   @override
   Future<void> visitCombinatorsBegin(CombinatorsBegin node) =>
       defaultNode(node);

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body.dart

@@ -0,0 +1,15 @@
+class C1() {
+  this {}
+}
+
+class C2() {
+  this : assert(1 > 2) {}
+}
+
+class C3() {
+  this;
+}
+
+class C4() {
+  this : assert(1 > 2);
+}

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body.dart.expect

@@ -0,0 +1,134 @@
+beginCompilationUnit(class)
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C1, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C1)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endPrimaryConstructorBody(this, this, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C2, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C2)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endPrimaryConstructorBody(this, this, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C3, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C3)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+          endPrimaryConstructorBody(this, this, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C4, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C4)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+          endPrimaryConstructorBody(this, this, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body.dart.intertwined.expect

@@ -0,0 +1,264 @@
+parseUnit(class)
+  skipErrorTokens(class)
+  listener: beginCompilationUnit(class)
+  syntheticPreviousToken(class)
+  parseTopLevelDeclarationImpl(, DirectiveContext(DirectiveState.Unknown))
+    parseMetadataStar()
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, , class, null, null, null, null, DirectiveContext(DirectiveState.Unknown))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C1, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C1)
+        parseClass(C1, class, class, null, C1)
+          parsePrimaryConstructorOpt(C1, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C1, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C1)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C1)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt(this)
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(this, false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                listener: endPrimaryConstructorBody(this, this, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, }, class, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C2, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C2)
+        parseClass(C2, class, class, null, C2)
+          parsePrimaryConstructorOpt(C2, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C2, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C2)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C2)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                listener: endPrimaryConstructorBody(this, this, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, }, class, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C3, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C3)
+        parseClass(C3, class, class, null, C3)
+          parsePrimaryConstructorOpt(C3, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C3, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C3)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C3)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt(this)
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(this, false, true)
+                  listener: handleEmptyFunctionBody(;)
+                listener: endPrimaryConstructorBody(this, this, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, }, class, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C4, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C4)
+        parseClass(C4, class, class, null, C4)
+          parsePrimaryConstructorOpt(C4, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C4, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C4)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C4)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: handleEmptyFunctionBody(;)
+                listener: endPrimaryConstructorBody(this, this, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  reportAllErrorTokens(class)
+  listener: endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body.dart.parser.expect

@@ -0,0 +1,33 @@
+class C1() {
+this {}
+}
+
+class C2() {
+this : assert(1 > 2) {}
+}
+
+class C3() {
+this;
+}
+
+class C4() {
+this : assert(1 > 2);
+}
+
+
+class[KeywordToken] C1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken];[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body.dart.scanner.expect

@@ -0,0 +1,33 @@
+class C1() {
+this {}
+}
+
+class C2() {
+this : assert(1 > 2) {}
+}
+
+class C3() {
+this;
+}
+
+class C4() {
+this : assert(1 > 2);
+}
+
+
+class[KeywordToken] C1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken];[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body_error.dart

@@ -0,0 +1,15 @@
+class C1() {
+  this() {}
+}
+
+class C2() {
+  this(int x) : assert(1 > 2) {}
+}
+
+class C3() {
+  this();
+}
+
+class C4() {
+  this(int x) : assert(1 > 2);
+}

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body_error.dart.expect

@@ -0,0 +1,204 @@
+Problems reported:
+
+parser/declaring_constructors/class_primary_constructor_body_error:2:3: 'this' can't be used as an identifier because it's a keyword.
+  this() {}
+  ^^^^
+
+parser/declaring_constructors/class_primary_constructor_body_error:6:3: 'this' can't be used as an identifier because it's a keyword.
+  this(int x) : assert(1 > 2) {}
+  ^^^^
+
+parser/declaring_constructors/class_primary_constructor_body_error:6:3: The name of a constructor must match the name of the enclosing class.
+  this(int x) : assert(1 > 2) {}
+  ^^^^
+
+parser/declaring_constructors/class_primary_constructor_body_error:10:3: 'this' can't be used as an identifier because it's a keyword.
+  this();
+  ^^^^
+
+parser/declaring_constructors/class_primary_constructor_body_error:14:3: 'this' can't be used as an identifier because it's a keyword.
+  this(int x) : assert(1 > 2);
+  ^^^^
+
+parser/declaring_constructors/class_primary_constructor_body_error:14:3: The name of a constructor must match the name of the enclosing class.
+  this(int x) : assert(1 > 2);
+  ^^^^
+
+beginCompilationUnit(class)
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C1, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C1)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C1)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.NonStaticMethod)
+            endFormalParameters(0, (, ), MemberKind.NonStaticMethod)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endClassMethod(null, this, (, null, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C2, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C2)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C2)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.NonStaticMethod)
+              beginMetadataStar(int)
+              endMetadataStar(0)
+              beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
+                handleIdentifier(int, typeReference)
+                handleNoTypeArguments(x)
+                handleType(int, null)
+                handleIdentifier(x, formalParameterDeclaration)
+                handleFormalParameterWithoutValue())
+              endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+            handleRecoverableError(ConstructorWithWrongName, this, this)
+          endClassConstructor(null, this, (, :, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C3, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C3)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C3)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.NonStaticMethod)
+            endFormalParameters(0, (, ), MemberKind.NonStaticMethod)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+          endClassMethod(null, this, (, null, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(class)
+  endMetadataStar(0)
+  beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+    handleIdentifier(C4, classOrMixinDeclaration)
+    handleNoTypeVariables(()
+    beginClassDeclaration(class, null, null, null, null, null, null, null, null, C4)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, false)
+      handleNoType())
+      handleClassExtends(null, 1)
+      handleClassNoWithClause()
+      handleImplements(null, 0)
+      handleClassHeader(class, class, null)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C4)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.NonStaticMethod)
+              beginMetadataStar(int)
+              endMetadataStar(0)
+              beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
+                handleIdentifier(int, typeReference)
+                handleNoTypeArguments(x)
+                handleType(int, null)
+                handleIdentifier(x, formalParameterDeclaration)
+                handleFormalParameterWithoutValue())
+              endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+            handleRecoverableError(ConstructorWithWrongName, this, this)
+          endClassConstructor(null, this, (, :, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+    endClassDeclaration(class, })
+  endTopLevelDeclaration(})
+endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body_error.dart.intertwined.expect

@@ -0,0 +1,344 @@
+parseUnit(class)
+  skipErrorTokens(class)
+  listener: beginCompilationUnit(class)
+  syntheticPreviousToken(class)
+  parseTopLevelDeclarationImpl(, DirectiveContext(DirectiveState.Unknown))
+    parseMetadataStar()
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, , class, null, null, null, null, DirectiveContext(DirectiveState.Unknown))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C1, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C1)
+        parseClass(C1, class, class, null, C1)
+          parsePrimaryConstructorOpt(C1, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C1, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C1)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C1)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.Class, C1, false)
+                listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C1)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.NonStaticMethod)
+                  parseFormalParameters(this, MemberKind.NonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.NonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.NonStaticMethod)
+                      listener: endFormalParameters(0, (, ), MemberKind.NonStaticMethod)
+                parseInitializersOpt())
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                listener: endClassMethod(null, this, (, null, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, }, class, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C2, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C2)
+        parseClass(C2, class, class, null, C2)
+          parsePrimaryConstructorOpt(C2, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C2, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C2)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C2)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.Class, C2, false)
+                listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C2)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.NonStaticMethod)
+                  parseFormalParameters(this, MemberKind.NonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.NonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.NonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(int)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
+                        listener: handleIdentifier(int, typeReference)
+                        listener: handleNoTypeArguments(x)
+                        listener: handleType(int, null)
+                        ensureIdentifier(int, formalParameterDeclaration)
+                          listener: handleIdentifier(x, formalParameterDeclaration)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+                parseInitializersOpt())
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                reportRecoverableError(this, ConstructorWithWrongName)
+                  listener: handleRecoverableError(ConstructorWithWrongName, this, this)
+                listener: endClassConstructor(null, this, (, :, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, }, class, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C3, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C3)
+        parseClass(C3, class, class, null, C3)
+          parsePrimaryConstructorOpt(C3, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C3, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C3)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C3)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.Class, C3, false)
+                listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C3)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.NonStaticMethod)
+                  parseFormalParameters(this, MemberKind.NonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.NonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.NonStaticMethod)
+                      listener: endFormalParameters(0, (, ), MemberKind.NonStaticMethod)
+                parseInitializersOpt())
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: handleEmptyFunctionBody(;)
+                listener: endClassMethod(null, this, (, null, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(class)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(class, }, class, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseClassOrNamedMixinApplication(class, null, null, null, null, null, null, null, null, class)
+        listener: beginClassOrMixinOrNamedMixinApplicationPrelude(class)
+        ensureIdentifier(class, classOrMixinDeclaration)
+          listener: handleIdentifier(C4, classOrMixinDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginClassDeclaration(class, null, null, null, null, null, null, null, null, C4)
+        parseClass(C4, class, class, null, C4)
+          parsePrimaryConstructorOpt(C4, null, false)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(C4, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, false)
+          parseClassHeaderOpt(), class, class)
+            parseClassExtendsOpt(), DeclarationHeaderKind.Class)
+              listener: handleNoType())
+              listener: handleClassExtends(null, 1)
+            parseClassWithClauseOpt())
+              listener: handleClassNoWithClause()
+            parseClassOrMixinOrEnumImplementsOpt())
+              listener: handleImplements(null, 0)
+            listener: handleClassHeader(class, class, null)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.Class, C4)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.Class, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.Class, C4)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.Class, C4, false)
+                listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, C4)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.NonStaticMethod)
+                  parseFormalParameters(this, MemberKind.NonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.NonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.NonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(int)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
+                        listener: handleIdentifier(int, typeReference)
+                        listener: handleNoTypeArguments(x)
+                        listener: handleType(int, null)
+                        ensureIdentifier(int, formalParameterDeclaration)
+                          listener: handleIdentifier(x, formalParameterDeclaration)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+                parseInitializersOpt())
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: handleEmptyFunctionBody(;)
+                reportRecoverableError(this, ConstructorWithWrongName)
+                  listener: handleRecoverableError(ConstructorWithWrongName, this, this)
+                listener: endClassConstructor(null, this, (, :, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 1, {, })
+          listener: endClassDeclaration(class, })
+  listener: endTopLevelDeclaration(})
+  reportAllErrorTokens(class)
+  listener: endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body_error.dart.parser.expect

@@ -0,0 +1,33 @@
+class C1() {
+this() {}
+}
+
+class C2() {
+this(int x) : assert(1 > 2) {}
+}
+
+class C3() {
+this();
+}
+
+class C4() {
+this(int x) : assert(1 > 2);
+}
+
+
+class[KeywordToken] C1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/class_primary_constructor_body_error.dart.scanner.expect

@@ -0,0 +1,33 @@
+class C1() {
+this() {}
+}
+
+class C2() {
+this(int x) : assert(1 > 2) {}
+}
+
+class C3() {
+this();
+}
+
+class C4() {
+this(int x) : assert(1 > 2);
+}
+
+
+class[KeywordToken] C1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+class[KeywordToken] C4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body.dart

@@ -0,0 +1,19 @@
+enum const E1() {
+  e;
+  this {}
+}
+
+enum const E2() {
+  e;
+  this : assert(1 > 2) {}
+}
+
+enum const E3() {
+  e;
+  this;
+}
+
+enum const E4() {
+  e;
+  this : assert(1 > 2);
+}

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body.dart.expect

@@ -0,0 +1,170 @@
+beginCompilationUnit(enum)
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E1, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E1)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(e)
+        endMetadataStar(0)
+        handleIdentifier(e, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(;)
+        beginConstructorReference(e)
+          handleNoTypeArguments(;)
+          handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+        endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+        handleNoArguments(e)
+        handleEnumElement({, null)
+        handleEnumElements(;, 1)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endPrimaryConstructorBody(this, this, })
+        endMember()
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 1, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E2, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E2)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(e)
+        endMetadataStar(0)
+        handleIdentifier(e, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(;)
+        beginConstructorReference(e)
+          handleNoTypeArguments(;)
+          handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+        endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+        handleNoArguments(e)
+        handleEnumElement({, null)
+        handleEnumElements(;, 1)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endPrimaryConstructorBody(this, this, })
+        endMember()
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 1, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E3, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E3)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(e)
+        endMetadataStar(0)
+        handleIdentifier(e, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(;)
+        beginConstructorReference(e)
+          handleNoTypeArguments(;)
+          handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+        endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+        handleNoArguments(e)
+        handleEnumElement({, null)
+        handleEnumElements(;, 1)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+          endPrimaryConstructorBody(this, this, ;)
+        endMember()
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 1, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E4, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E4)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(e)
+        endMetadataStar(0)
+        handleIdentifier(e, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(;)
+        beginConstructorReference(e)
+          handleNoTypeArguments(;)
+          handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+        endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+        handleNoArguments(e)
+        handleEnumElement({, null)
+        handleEnumElements(;, 1)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+          endPrimaryConstructorBody(this, this, ;)
+        endMember()
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 1, })
+  endTopLevelDeclaration(})
+endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body.dart.intertwined.expect

@@ -0,0 +1,300 @@
+parseUnit(enum)
+  skipErrorTokens(enum)
+  listener: beginCompilationUnit(enum)
+  syntheticPreviousToken(enum)
+  parseTopLevelDeclarationImpl(, DirectiveContext(DirectiveState.Unknown))
+    parseMetadataStar()
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, , enum, null, null, null, null, DirectiveContext(DirectiveState.Unknown))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E1, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E1)
+        parsePrimaryConstructorOpt(E1, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E1, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(e)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            listener: handleIdentifier(e, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(;)
+          listener: beginConstructorReference(e)
+          listener: handleNoTypeArguments(;)
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+          listener: endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+          listener: handleNoArguments(e)
+          listener: handleEnumElement({, null)
+        listener: handleEnumElements(;, 1)
+        notEofOrType(CLOSE_CURLY_BRACKET, this)
+        parseClassOrMixinOrExtensionOrEnumMemberImpl(;, DeclarationKind.Enum, E1)
+          parseMetadataStar(;)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          listener: beginMember()
+          parsePrimaryConstructorBody(this)
+            listener: beginPrimaryConstructorBody(this)
+            parseInitializersOpt(this)
+              listener: handleNoInitializers()
+            parseAsyncModifierOpt(this)
+              listener: handleAsyncModifier(null, null)
+              inPlainSync()
+            inPlainSync()
+            parseFunctionBody(this, false, true)
+              listener: beginBlockFunctionBody({)
+              notEofOrType(CLOSE_CURLY_BRACKET, })
+              listener: endBlockFunctionBody(0, {, })
+            listener: endPrimaryConstructorBody(this, this, })
+          listener: endMember()
+        notEofOrType(CLOSE_CURLY_BRACKET, })
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 1, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E2, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E2)
+        parsePrimaryConstructorOpt(E2, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E2, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(e)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            listener: handleIdentifier(e, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(;)
+          listener: beginConstructorReference(e)
+          listener: handleNoTypeArguments(;)
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+          listener: endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+          listener: handleNoArguments(e)
+          listener: handleEnumElement({, null)
+        listener: handleEnumElements(;, 1)
+        notEofOrType(CLOSE_CURLY_BRACKET, this)
+        parseClassOrMixinOrExtensionOrEnumMemberImpl(;, DeclarationKind.Enum, E2)
+          parseMetadataStar(;)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          listener: beginMember()
+          parsePrimaryConstructorBody(this)
+            listener: beginPrimaryConstructorBody(this)
+            parseInitializersOpt(this)
+              parseInitializers(:)
+                listener: beginInitializers(:)
+                parseInitializer(:)
+                  listener: beginInitializer(assert)
+                  parseAssert(:, Assert.Initializer)
+                    listener: beginAssert(assert, Assert.Initializer)
+                    parseExpression(()
+                      looksLikeOuterPatternEquals(()
+                        skipOuterPattern(()
+                      parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                        parseUnaryExpression((, true, ConstantPatternContext.none)
+                          parsePrimary((, expression, ConstantPatternContext.none)
+                            parseLiteralInt(()
+                              listener: handleLiteralInt(1)
+                        listener: beginBinaryExpression(>)
+                        parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                          parseUnaryExpression(>, true, ConstantPatternContext.none)
+                            parsePrimary(>, expression, ConstantPatternContext.none)
+                              parseLiteralInt(>)
+                                listener: handleLiteralInt(2)
+                        listener: endBinaryExpression(>, 2)
+                    listener: endAssert(assert, Assert.Initializer, (, null, ))
+                  listener: endInitializer())
+                listener: endInitializers(1, :, ))
+            parseAsyncModifierOpt())
+              listener: handleAsyncModifier(null, null)
+              inPlainSync()
+            inPlainSync()
+            parseFunctionBody(), false, true)
+              listener: beginBlockFunctionBody({)
+              notEofOrType(CLOSE_CURLY_BRACKET, })
+              listener: endBlockFunctionBody(0, {, })
+            listener: endPrimaryConstructorBody(this, this, })
+          listener: endMember()
+        notEofOrType(CLOSE_CURLY_BRACKET, })
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 1, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E3, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E3)
+        parsePrimaryConstructorOpt(E3, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E3, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(e)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            listener: handleIdentifier(e, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(;)
+          listener: beginConstructorReference(e)
+          listener: handleNoTypeArguments(;)
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+          listener: endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+          listener: handleNoArguments(e)
+          listener: handleEnumElement({, null)
+        listener: handleEnumElements(;, 1)
+        notEofOrType(CLOSE_CURLY_BRACKET, this)
+        parseClassOrMixinOrExtensionOrEnumMemberImpl(;, DeclarationKind.Enum, E3)
+          parseMetadataStar(;)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          listener: beginMember()
+          parsePrimaryConstructorBody(this)
+            listener: beginPrimaryConstructorBody(this)
+            parseInitializersOpt(this)
+              listener: handleNoInitializers()
+            parseAsyncModifierOpt(this)
+              listener: handleAsyncModifier(null, null)
+              inPlainSync()
+            inPlainSync()
+            parseFunctionBody(this, false, true)
+              listener: handleEmptyFunctionBody(;)
+            listener: endPrimaryConstructorBody(this, this, ;)
+          listener: endMember()
+        notEofOrType(CLOSE_CURLY_BRACKET, })
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 1, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E4, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E4)
+        parsePrimaryConstructorOpt(E4, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E4, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(e)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            listener: handleIdentifier(e, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(;)
+          listener: beginConstructorReference(e)
+          listener: handleNoTypeArguments(;)
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(e)
+          listener: endConstructorReference(e, null, e, ConstructorReferenceContext.Const)
+          listener: handleNoArguments(e)
+          listener: handleEnumElement({, null)
+        listener: handleEnumElements(;, 1)
+        notEofOrType(CLOSE_CURLY_BRACKET, this)
+        parseClassOrMixinOrExtensionOrEnumMemberImpl(;, DeclarationKind.Enum, E4)
+          parseMetadataStar(;)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          listener: beginMember()
+          parsePrimaryConstructorBody(this)
+            listener: beginPrimaryConstructorBody(this)
+            parseInitializersOpt(this)
+              parseInitializers(:)
+                listener: beginInitializers(:)
+                parseInitializer(:)
+                  listener: beginInitializer(assert)
+                  parseAssert(:, Assert.Initializer)
+                    listener: beginAssert(assert, Assert.Initializer)
+                    parseExpression(()
+                      looksLikeOuterPatternEquals(()
+                        skipOuterPattern(()
+                      parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                        parseUnaryExpression((, true, ConstantPatternContext.none)
+                          parsePrimary((, expression, ConstantPatternContext.none)
+                            parseLiteralInt(()
+                              listener: handleLiteralInt(1)
+                        listener: beginBinaryExpression(>)
+                        parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                          parseUnaryExpression(>, true, ConstantPatternContext.none)
+                            parsePrimary(>, expression, ConstantPatternContext.none)
+                              parseLiteralInt(>)
+                                listener: handleLiteralInt(2)
+                        listener: endBinaryExpression(>, 2)
+                    listener: endAssert(assert, Assert.Initializer, (, null, ))
+                  listener: endInitializer())
+                listener: endInitializers(1, :, ))
+            parseAsyncModifierOpt())
+              listener: handleAsyncModifier(null, null)
+              inPlainSync()
+            inPlainSync()
+            parseFunctionBody(), false, true)
+              listener: handleEmptyFunctionBody(;)
+            listener: endPrimaryConstructorBody(this, this, ;)
+          listener: endMember()
+        notEofOrType(CLOSE_CURLY_BRACKET, })
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 1, })
+  listener: endTopLevelDeclaration(})
+  reportAllErrorTokens(enum)
+  listener: endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body.dart.parser.expect

@@ -0,0 +1,41 @@
+enum const E1() {
+e;
+this {}
+}
+
+enum const E2() {
+e;
+this : assert(1 > 2) {}
+}
+
+enum const E3() {
+e;
+this;
+}
+
+enum const E4() {
+e;
+this : assert(1 > 2);
+}
+
+
+enum[KeywordToken] const[KeywordToken] E1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body.dart.scanner.expect

@@ -0,0 +1,41 @@
+enum const E1() {
+e;
+this {}
+}
+
+enum const E2() {
+e;
+this : assert(1 > 2) {}
+}
+
+enum const E3() {
+e;
+this;
+}
+
+enum const E4() {
+e;
+this : assert(1 > 2);
+}
+
+
+enum[KeywordToken] const[KeywordToken] E1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+e[StringToken];[SimpleToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body_error.dart

@@ -0,0 +1,23 @@
+enum const E1() {
+  this() {}
+}
+
+enum const E2() {
+  this(int x) : assert(1 > 2) {}
+}
+
+enum const E3() {
+  this();
+}
+
+enum const E4() {
+  this(int x) : assert(1 > 2);
+}
+
+enum const E5() { // missing constants
+  this : assert(1 > 2);
+}
+
+enum const E6() { // missing constants
+  this {}
+}

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body_error.dart.expect

@@ -0,0 +1,257 @@
+Problems reported:
+
+parser/declaring_constructors/enum_primary_constructor_body_error:2:3: 'this' can't be used as an identifier because it's a keyword.
+  this() {}
+  ^^^^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:2:10: Expected '}' before this.
+  this() {}
+         ^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:6:3: 'this' can't be used as an identifier because it's a keyword.
+  this(int x) : assert(1 > 2) {}
+  ^^^^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:6:12: Expected ',' before this.
+  this(int x) : assert(1 > 2) {}
+           ^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:6:15: Expected '}' before this.
+  this(int x) : assert(1 > 2) {}
+              ^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:10:3: 'this' can't be used as an identifier because it's a keyword.
+  this();
+  ^^^^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:14:3: 'this' can't be used as an identifier because it's a keyword.
+  this(int x) : assert(1 > 2);
+  ^^^^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:14:12: Expected ',' before this.
+  this(int x) : assert(1 > 2);
+           ^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:14:15: Expected '}' before this.
+  this(int x) : assert(1 > 2);
+              ^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:18:3: 'this' can't be used as an identifier because it's a keyword.
+  this : assert(1 > 2);
+  ^^^^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:18:8: Expected '}' before this.
+  this : assert(1 > 2);
+       ^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:22:3: 'this' can't be used as an identifier because it's a keyword.
+  this {}
+  ^^^^
+
+parser/declaring_constructors/enum_primary_constructor_body_error:22:8: Expected '}' before this.
+  this {}
+       ^
+
+beginCompilationUnit(enum)
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E1, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E1)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+        handleIdentifier(this, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(()
+        beginConstructorReference(this)
+          handleNoTypeArguments(()
+          handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+        endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+        beginArguments(()
+        endArguments(0, (, ))
+        handleEnumElement({, null)
+        handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], {, {)
+        handleEnumElements(}, 1)
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 0, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E2, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E2)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+        handleIdentifier(this, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(()
+        beginConstructorReference(this)
+          handleNoTypeArguments(()
+          handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+        endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+        beginArguments(()
+          handleIdentifier(int, expression)
+          handleNoTypeArguments(x)
+          handleNoArguments(x)
+          handleSend(int, int)
+          handleRecoverableError(Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}], x, x)
+          handleIdentifier(x, expression)
+          handleNoTypeArguments())
+          handleNoArguments())
+          handleSend(x, x)
+        endArguments(2, (, ))
+        handleEnumElement({, null)
+        handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], :, :)
+        handleEnumElements(}, 1)
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 0, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E3, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E3)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+        handleIdentifier(this, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(()
+        beginConstructorReference(this)
+          handleNoTypeArguments(()
+          handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+        endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+        beginArguments(()
+        endArguments(0, (, ))
+        handleEnumElement({, null)
+        handleEnumElements(;, 1)
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 0, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E4, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E4)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+        handleIdentifier(this, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(()
+        beginConstructorReference(this)
+          handleNoTypeArguments(()
+          handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+        endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+        beginArguments(()
+          handleIdentifier(int, expression)
+          handleNoTypeArguments(x)
+          handleNoArguments(x)
+          handleSend(int, int)
+          handleRecoverableError(Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}], x, x)
+          handleIdentifier(x, expression)
+          handleNoTypeArguments())
+          handleNoArguments())
+          handleSend(x, x)
+        endArguments(2, (, ))
+        handleEnumElement({, null)
+        handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], :, :)
+        handleEnumElements(}, 1)
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 0, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E5, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E5)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+        handleIdentifier(this, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference(:)
+        beginConstructorReference(this)
+          handleNoTypeArguments(:)
+          handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+        endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+        handleNoArguments(this)
+        handleEnumElement({, null)
+        handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], :, :)
+        handleEnumElements(}, 1)
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 0, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(enum)
+  endMetadataStar(0)
+  beginEnumDeclarationPrelude(enum)
+    handleIdentifier(E6, enumDeclaration)
+    handleNoTypeVariables(()
+    beginEnumDeclaration(enum, null, enum, E6)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+        endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, const, false, false)
+      handleEnumNoWithClause()
+      handleImplements(null, 0)
+      handleEnumHeader(null, enum, {)
+      beginEnumBody({)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+        handleIdentifier(this, enumValueDeclaration)
+        handleNoTypeNameInConstructorReference({)
+        beginConstructorReference(this)
+          handleNoTypeArguments({)
+          handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+        endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+        handleNoArguments(this)
+        handleEnumElement({, null)
+        handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], {, {)
+        handleEnumElements(}, 1)
+      endEnumBody({, })
+    endEnumDeclaration(enum, enum, {, 0, })
+  endTopLevelDeclaration(})
+endCompilationUnit(6, )

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body_error.dart.intertwined.expect

@@ -0,0 +1,343 @@
+parseUnit(enum)
+  skipErrorTokens(enum)
+  listener: beginCompilationUnit(enum)
+  syntheticPreviousToken(enum)
+  parseTopLevelDeclarationImpl(, DirectiveContext(DirectiveState.Unknown))
+    parseMetadataStar()
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, , enum, null, null, null, null, DirectiveContext(DirectiveState.Unknown))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E1, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E1)
+        parsePrimaryConstructorOpt(E1, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E1, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+              listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            listener: handleIdentifier(this, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(()
+          listener: beginConstructorReference(this)
+          listener: handleNoTypeArguments(()
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+          listener: endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+          parseConstructorInvocationArguments(this)
+            parseArgumentsRest(()
+              listener: beginArguments(()
+              listener: endArguments(0, (, ))
+          listener: handleEnumElement({, null)
+        reportRecoverableError({, Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}])
+          listener: handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], {, {)
+        listener: handleEnumElements(}, 1)
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 0, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E2, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E2)
+        parsePrimaryConstructorOpt(E2, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E2, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+              listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            listener: handleIdentifier(this, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(()
+          listener: beginConstructorReference(this)
+          listener: handleNoTypeArguments(()
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+          listener: endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+          parseConstructorInvocationArguments(this)
+            parseArgumentsRest(()
+              listener: beginArguments(()
+              allowedToShortcutParseExpression()
+              parseExpression(()
+                looksLikeOuterPatternEquals(()
+                  skipOuterPattern(()
+                    skipObjectPatternRest(int)
+                parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                  parseUnaryExpression((, true, ConstantPatternContext.none)
+                    parsePrimary((, expression, ConstantPatternContext.none)
+                      parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
+                        parseSend((, expression, ConstantPatternContext.none)
+                          ensureIdentifier((, expression)
+                            listener: handleIdentifier(int, expression)
+                          listener: handleNoTypeArguments(x)
+                          parseArgumentsOpt(int)
+                            listener: handleNoArguments(x)
+                          listener: handleSend(int, int)
+              rewriteAndRecover(int, Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}], ,)
+                reportRecoverableError(x, Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}])
+                  listener: handleRecoverableError(Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}], x, x)
+                rewriter()
+              allowedToShortcutParseExpression()
+              listener: handleIdentifier(x, expression)
+              listener: handleNoTypeArguments())
+              listener: handleNoArguments())
+              listener: handleSend(x, x)
+              listener: endArguments(2, (, ))
+          listener: handleEnumElement({, null)
+        reportRecoverableError(:, Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}])
+          listener: handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], :, :)
+        listener: handleEnumElements(}, 1)
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 0, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E3, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E3)
+        parsePrimaryConstructorOpt(E3, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E3, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+              listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            listener: handleIdentifier(this, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(()
+          listener: beginConstructorReference(this)
+          listener: handleNoTypeArguments(()
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+          listener: endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+          parseConstructorInvocationArguments(this)
+            parseArgumentsRest(()
+              listener: beginArguments(()
+              listener: endArguments(0, (, ))
+          listener: handleEnumElement({, null)
+        listener: handleEnumElements(;, 1)
+        notEofOrType(CLOSE_CURLY_BRACKET, })
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 0, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E4, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E4)
+        parsePrimaryConstructorOpt(E4, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E4, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+              listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            listener: handleIdentifier(this, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(()
+          listener: beginConstructorReference(this)
+          listener: handleNoTypeArguments(()
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+          listener: endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+          parseConstructorInvocationArguments(this)
+            parseArgumentsRest(()
+              listener: beginArguments(()
+              allowedToShortcutParseExpression()
+              parseExpression(()
+                looksLikeOuterPatternEquals(()
+                  skipOuterPattern(()
+                    skipObjectPatternRest(int)
+                parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                  parseUnaryExpression((, true, ConstantPatternContext.none)
+                    parsePrimary((, expression, ConstantPatternContext.none)
+                      parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
+                        parseSend((, expression, ConstantPatternContext.none)
+                          ensureIdentifier((, expression)
+                            listener: handleIdentifier(int, expression)
+                          listener: handleNoTypeArguments(x)
+                          parseArgumentsOpt(int)
+                            listener: handleNoArguments(x)
+                          listener: handleSend(int, int)
+              rewriteAndRecover(int, Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}], ,)
+                reportRecoverableError(x, Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}])
+                  listener: handleRecoverableError(Message[Template(ExpectedButGot), Expected ',' before this., null, {string: ,}], x, x)
+                rewriter()
+              allowedToShortcutParseExpression()
+              listener: handleIdentifier(x, expression)
+              listener: handleNoTypeArguments())
+              listener: handleNoArguments())
+              listener: handleSend(x, x)
+              listener: endArguments(2, (, ))
+          listener: handleEnumElement({, null)
+        reportRecoverableError(:, Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}])
+          listener: handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], :, :)
+        listener: handleEnumElements(}, 1)
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 0, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E5, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E5)
+        parsePrimaryConstructorOpt(E5, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E5, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+              listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            listener: handleIdentifier(this, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference(:)
+          listener: beginConstructorReference(this)
+          listener: handleNoTypeArguments(:)
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+          listener: endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+          listener: handleNoArguments(this)
+          listener: handleEnumElement({, null)
+        reportRecoverableError(:, Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}])
+          listener: handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], :, :)
+        listener: handleEnumElements(}, 1)
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 0, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(enum)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(enum, }, enum, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseEnum(enum, null, enum)
+        listener: beginEnumDeclarationPrelude(enum)
+        ensureIdentifier(const, enumDeclaration)
+          listener: handleIdentifier(E6, enumDeclaration)
+        listener: handleNoTypeVariables(()
+        listener: beginEnumDeclaration(enum, null, enum, E6)
+        parsePrimaryConstructorOpt(E6, const, false)
+          listener: beginPrimaryConstructor(()
+          parseFormalParameters(E6, MemberKind.PrimaryConstructor)
+            parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+              listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+              listener: endFormalParameters(0, (, ), MemberKind.PrimaryConstructor)
+          listener: endPrimaryConstructor((, const, false, false)
+        parseEnumHeaderOpt(), enum)
+          parseEnumWithClauseOpt())
+            listener: handleEnumNoWithClause()
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+        listener: handleEnumHeader(null, enum, {)
+        listener: beginEnumBody({)
+        parseEnumElement({)
+          parseMetadataStar({)
+            listener: beginMetadataStar(this)
+            listener: endMetadataStar(0)
+          ensureIdentifier({, enumValueDeclaration)
+            reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+              listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            listener: handleIdentifier(this, enumValueDeclaration)
+          listener: handleNoTypeNameInConstructorReference({)
+          listener: beginConstructorReference(this)
+          listener: handleNoTypeArguments({)
+          listener: handleNoConstructorReferenceContinuationAfterTypeArguments(this)
+          listener: endConstructorReference(this, null, this, ConstructorReferenceContext.Const)
+          listener: handleNoArguments(this)
+          listener: handleEnumElement({, null)
+        reportRecoverableError({, Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}])
+          listener: handleRecoverableError(Message[Template(ExpectedButGot), Expected '}' before this., null, {string: }}], {, {)
+        listener: handleEnumElements(}, 1)
+        listener: endEnumBody({, })
+        listener: endEnumDeclaration(enum, enum, {, 0, })
+  listener: endTopLevelDeclaration(})
+  reportAllErrorTokens(enum)
+  listener: endCompilationUnit(6, )

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body_error.dart.parser.expect

@@ -0,0 +1,51 @@
+NOTICE: Stream was rewritten by parser!
+
+enum const E1() {
+this() {}
+}
+
+enum const E2() {
+this(int ,x) : assert(1 > 2) {}
+}
+
+enum const E3() {
+this();
+}
+
+enum const E4() {
+this(int ,x) : assert(1 > 2);
+}
+
+enum const E5() {
+this : assert(1 > 2);
+}
+
+enum const E6() {
+this {}
+}
+
+
+enum[KeywordToken] const[KeywordToken] E1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] ,[SyntheticToken]x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] ,[SyntheticToken]x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E5[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E6[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/enum_primary_constructor_body_error.dart.scanner.expect

@@ -0,0 +1,49 @@
+enum const E1() {
+this() {}
+}
+
+enum const E2() {
+this(int x) : assert(1 > 2) {}
+}
+
+enum const E3() {
+this();
+}
+
+enum const E4() {
+this(int x) : assert(1 > 2);
+}
+
+enum const E5() {
+this : assert(1 > 2);
+}
+
+enum const E6() {
+this {}
+}
+
+
+enum[KeywordToken] const[KeywordToken] E1[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E2[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E3[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E4[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E5[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+
+enum[KeywordToken] const[KeywordToken] E6[StringToken]([BeginToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body.dart

@@ -0,0 +1,15 @@
+extension type E1(int x) {
+  this {}
+}
+
+extension type E2(int x) {
+  this : assert(1 > 2) {}
+}
+
+extension type E3(int x) {
+  this;
+}
+
+extension type E4(int x) {
+  this : assert(1 > 2);
+}

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body.dart.expect

@@ -0,0 +1,150 @@
+beginCompilationUnit(extension)
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E1)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endPrimaryConstructorBody(this, this, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E2)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endPrimaryConstructorBody(this, this, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E3)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+          endPrimaryConstructorBody(this, this, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E4)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginPrimaryConstructorBody(this)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+          endPrimaryConstructorBody(this, this, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body.dart.intertwined.expect

@@ -0,0 +1,276 @@
+parseUnit(extension)
+  skipErrorTokens(extension)
+  listener: beginCompilationUnit(extension)
+  syntheticPreviousToken(extension)
+  parseTopLevelDeclarationImpl(, DirectiveContext(DirectiveState.Unknown))
+    parseMetadataStar()
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, , extension, null, null, null, null, DirectiveContext(DirectiveState.Unknown))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E1)
+          parsePrimaryConstructorOpt(E1, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E1, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E1)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E1)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt(this)
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(this, false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                listener: endPrimaryConstructorBody(this, this, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, }, extension, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E2)
+          parsePrimaryConstructorOpt(E2, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E2, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E2)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E2)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                listener: endPrimaryConstructorBody(this, this, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, }, extension, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E3)
+          parsePrimaryConstructorOpt(E3, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E3, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E3)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E3)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt(this)
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(this, false, true)
+                  listener: handleEmptyFunctionBody(;)
+                listener: endPrimaryConstructorBody(this, this, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, }, extension, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E4)
+          parsePrimaryConstructorOpt(E4, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E4, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E4)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E4)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parsePrimaryConstructorBody(this)
+                listener: beginPrimaryConstructorBody(this)
+                parseInitializersOpt(this)
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: handleEmptyFunctionBody(;)
+                listener: endPrimaryConstructorBody(this, this, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  reportAllErrorTokens(extension)
+  listener: endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body.dart.parser.expect

@@ -0,0 +1,33 @@
+extension type E1(int x) {
+this {}
+}
+
+extension type E2(int x) {
+this : assert(1 > 2) {}
+}
+
+extension type E3(int x) {
+this;
+}
+
+extension type E4(int x) {
+this : assert(1 > 2);
+}
+
+
+extension[KeywordToken] type[StringToken] E1[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E2[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E3[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken];[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E4[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body.dart.scanner.expect

@@ -0,0 +1,33 @@
+extension type E1(int x) {
+this {}
+}
+
+extension type E2(int x) {
+this : assert(1 > 2) {}
+}
+
+extension type E3(int x) {
+this;
+}
+
+extension type E4(int x) {
+this : assert(1 > 2);
+}
+
+
+extension[KeywordToken] type[StringToken] E1[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E2[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E3[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken];[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E4[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body_error.dart

@@ -0,0 +1,15 @@
+extension type E1(int x) {
+  this(this.x) {}
+}
+
+extension type E2(int x) {
+  this(this.x)  : assert(1 > 2) {}
+}
+
+extension type E3(int x) {
+  this(this.x) ;
+}
+
+extension type E4(int x) {
+  this(this.x)  : assert(1 > 2);
+}

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body_error.dart.expect

@@ -0,0 +1,235 @@
+Problems reported:
+
+parser/declaring_constructors/extension_type_primary_constructor_body_error:2:3: 'this' can't be used as an identifier because it's a keyword.
+  this(this.x) {}
+  ^^^^
+
+parser/declaring_constructors/extension_type_primary_constructor_body_error:6:3: 'this' can't be used as an identifier because it's a keyword.
+  this(this.x)  : assert(1 > 2) {}
+  ^^^^
+
+parser/declaring_constructors/extension_type_primary_constructor_body_error:6:3: The name of a constructor must match the name of the enclosing class.
+  this(this.x)  : assert(1 > 2) {}
+  ^^^^
+
+parser/declaring_constructors/extension_type_primary_constructor_body_error:10:3: 'this' can't be used as an identifier because it's a keyword.
+  this(this.x) ;
+  ^^^^
+
+parser/declaring_constructors/extension_type_primary_constructor_body_error:10:3: Extension types can't declare abstract members.
+  this(this.x) ;
+  ^^^^
+
+parser/declaring_constructors/extension_type_primary_constructor_body_error:14:3: 'this' can't be used as an identifier because it's a keyword.
+  this(this.x)  : assert(1 > 2);
+  ^^^^
+
+parser/declaring_constructors/extension_type_primary_constructor_body_error:14:3: The name of a constructor must match the name of the enclosing class.
+  this(this.x)  : assert(1 > 2);
+  ^^^^
+
+beginCompilationUnit(extension)
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E1)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E1)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+              beginMetadataStar(this)
+              endMetadataStar(0)
+              beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                handleNoType(()
+                handleIdentifier(x, fieldInitializer)
+                handleFormalParameterWithoutValue())
+              endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+          endExtensionTypeMethod(null, this, (, null, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E2)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E2)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+              beginMetadataStar(this)
+              endMetadataStar(0)
+              beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                handleNoType(()
+                handleIdentifier(x, fieldInitializer)
+                handleFormalParameterWithoutValue())
+              endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            beginBlockFunctionBody({)
+            endBlockFunctionBody(0, {, })
+            handleRecoverableError(ConstructorWithWrongName, this, this)
+          endExtensionTypeConstructor(null, this, (, :, })
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E3)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E3)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+              beginMetadataStar(this)
+              endMetadataStar(0)
+              beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                handleNoType(()
+                handleIdentifier(x, fieldInitializer)
+                handleFormalParameterWithoutValue())
+              endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+            handleNoInitializers()
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+            handleRecoverableError(ExtensionTypeDeclaresAbstractMember, this, this)
+          endExtensionTypeMethod(null, this, (, null, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+  beginMetadataStar(extension)
+  endMetadataStar(0)
+  beginExtensionDeclarationPrelude(extension)
+    handleNoTypeVariables(()
+    beginExtensionTypeDeclaration(null, extension, E4)
+      beginPrimaryConstructor(()
+        beginFormalParameters((, MemberKind.PrimaryConstructor)
+          beginMetadataStar(int)
+          endMetadataStar(0)
+          beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+            handleIdentifier(int, typeReference)
+            handleNoTypeArguments(x)
+            handleType(int, null)
+            handleIdentifier(x, formalParameterDeclaration)
+            handleFormalParameterWithoutValue())
+          endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+        endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+      endPrimaryConstructor((, null, false, true)
+      handleImplements(null, 0)
+      beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+        beginMetadataStar(this)
+        endMetadataStar(0)
+        beginMember()
+          beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E4)
+            handleNoType({)
+            handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+            handleIdentifier(this, methodDeclaration)
+            handleNoTypeVariables(()
+            beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+              beginMetadataStar(this)
+              endMetadataStar(0)
+              beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                handleNoType(()
+                handleIdentifier(x, fieldInitializer)
+                handleFormalParameterWithoutValue())
+              endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+            beginInitializers(:)
+              beginInitializer(assert)
+                beginAssert(assert, Assert.Initializer)
+                  handleLiteralInt(1)
+                  beginBinaryExpression(>)
+                    handleLiteralInt(2)
+                  endBinaryExpression(>, 2)
+                endAssert(assert, Assert.Initializer, (, null, ))
+              endInitializer())
+            endInitializers(1, :, ))
+            handleAsyncModifier(null, null)
+            handleEmptyFunctionBody(;)
+            handleRecoverableError(ConstructorWithWrongName, this, this)
+          endExtensionTypeConstructor(null, this, (, :, ;)
+        endMember()
+      endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+    endExtensionTypeDeclaration(extension, null, extension, type, })
+  endTopLevelDeclaration(})
+endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body_error.dart.intertwined.expect

@@ -0,0 +1,374 @@
+parseUnit(extension)
+  skipErrorTokens(extension)
+  listener: beginCompilationUnit(extension)
+  syntheticPreviousToken(extension)
+  parseTopLevelDeclarationImpl(, DirectiveContext(DirectiveState.Unknown))
+    parseMetadataStar()
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, , extension, null, null, null, null, DirectiveContext(DirectiveState.Unknown))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E1)
+          parsePrimaryConstructorOpt(E1, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E1, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E1)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E1)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.ExtensionType, E1, false)
+                listener: beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E1)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.ExtensionTypeNonStaticMethod)
+                  parseFormalParameters(this, MemberKind.ExtensionTypeNonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(this)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                        listener: handleNoType(()
+                        ensureIdentifier(., fieldInitializer)
+                          listener: handleIdentifier(x, fieldInitializer)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+                parseInitializersOpt())
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                listener: endExtensionTypeMethod(null, this, (, null, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, }, extension, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E2)
+          parsePrimaryConstructorOpt(E2, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E2, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E2)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E2)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.ExtensionType, E2, false)
+                listener: beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E2)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.ExtensionTypeNonStaticMethod)
+                  parseFormalParameters(this, MemberKind.ExtensionTypeNonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(this)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                        listener: handleNoType(()
+                        ensureIdentifier(., fieldInitializer)
+                          listener: handleIdentifier(x, fieldInitializer)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+                parseInitializersOpt())
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(0, {, })
+                reportRecoverableError(this, ConstructorWithWrongName)
+                  listener: handleRecoverableError(ConstructorWithWrongName, this, this)
+                listener: endExtensionTypeConstructor(null, this, (, :, })
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, }, extension, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E3)
+          parsePrimaryConstructorOpt(E3, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E3, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E3)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E3)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.ExtensionType, E3, false)
+                listener: beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E3)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.ExtensionTypeNonStaticMethod)
+                  parseFormalParameters(this, MemberKind.ExtensionTypeNonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(this)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                        listener: handleNoType(()
+                        ensureIdentifier(., fieldInitializer)
+                          listener: handleIdentifier(x, fieldInitializer)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+                parseInitializersOpt())
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: handleEmptyFunctionBody(;)
+                reportRecoverableError(this, ExtensionTypeDeclaresAbstractMember)
+                  listener: handleRecoverableError(ExtensionTypeDeclaresAbstractMember, this, this)
+                listener: endExtensionTypeMethod(null, this, (, null, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  parseTopLevelDeclarationImpl(}, DirectiveContext(DirectiveState.Declarations))
+    parseMetadataStar(})
+      listener: beginMetadataStar(extension)
+      listener: endMetadataStar(0)
+    parseTopLevelKeywordDeclaration(extension, }, extension, null, null, null, null, DirectiveContext(DirectiveState.Declarations))
+      parseExtension(extension, null, extension)
+        listener: beginExtensionDeclarationPrelude(extension)
+        parseExtensionTypeDeclaration(extension, type, null, extension, type)
+          listener: handleNoTypeVariables(()
+          listener: beginExtensionTypeDeclaration(null, extension, E4)
+          parsePrimaryConstructorOpt(E4, null, true)
+            listener: beginPrimaryConstructor(()
+            parseFormalParameters(E4, MemberKind.PrimaryConstructor)
+              parseFormalParametersRest((, MemberKind.PrimaryConstructor)
+                listener: beginFormalParameters((, MemberKind.PrimaryConstructor)
+                parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                  parseMetadataStar(()
+                    listener: beginMetadataStar(int)
+                    listener: endMetadataStar(0)
+                  listener: beginFormalParameter(int, MemberKind.PrimaryConstructor, null, null, null)
+                  listener: handleIdentifier(int, typeReference)
+                  listener: handleNoTypeArguments(x)
+                  listener: handleType(int, null)
+                  ensureIdentifier(int, formalParameterDeclaration)
+                    listener: handleIdentifier(x, formalParameterDeclaration)
+                  listener: handleFormalParameterWithoutValue())
+                  listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.PrimaryConstructor)
+                listener: endFormalParameters(1, (, ), MemberKind.PrimaryConstructor)
+            listener: endPrimaryConstructor((, null, false, true)
+          parseClassOrMixinOrEnumImplementsOpt())
+            listener: handleImplements(null, 0)
+          parseClassOrMixinOrExtensionBody(), DeclarationKind.ExtensionType, E4)
+            listener: beginClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, {)
+            notEofOrType(CLOSE_CURLY_BRACKET, this)
+            parseClassOrMixinOrExtensionOrEnumMemberImpl({, DeclarationKind.ExtensionType, E4)
+              parseMetadataStar({)
+                listener: beginMetadataStar(this)
+                listener: endMetadataStar(0)
+              listener: beginMember()
+              parseMethod({, null, null, null, null, null, null, null, {, NoType(), null, this, DeclarationKind.ExtensionType, E4, false)
+                listener: beginMethod(DeclarationKind.ExtensionType, null, null, null, null, null, null, this, E4)
+                listener: handleNoType({)
+                ensureIdentifierPotentiallyRecovered({, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.ExtensionTypeNonStaticMethod)
+                  parseFormalParameters(this, MemberKind.ExtensionTypeNonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.ExtensionTypeNonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(this)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(this, MemberKind.ExtensionTypeNonStaticMethod, null, null, null)
+                        listener: handleNoType(()
+                        ensureIdentifier(., fieldInitializer)
+                          listener: handleIdentifier(x, fieldInitializer)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, this, null, ., x, null, null, FormalParameterKind.requiredPositional, MemberKind.ExtensionTypeNonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.ExtensionTypeNonStaticMethod)
+                parseInitializersOpt())
+                  parseInitializers(:)
+                    listener: beginInitializers(:)
+                    parseInitializer(:)
+                      listener: beginInitializer(assert)
+                      parseAssert(:, Assert.Initializer)
+                        listener: beginAssert(assert, Assert.Initializer)
+                        parseExpression(()
+                          looksLikeOuterPatternEquals(()
+                            skipOuterPattern(()
+                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression((, true, ConstantPatternContext.none)
+                              parsePrimary((, expression, ConstantPatternContext.none)
+                                parseLiteralInt(()
+                                  listener: handleLiteralInt(1)
+                            listener: beginBinaryExpression(>)
+                            parsePrecedenceExpression(>, 9, true, ConstantPatternContext.none)
+                              parseUnaryExpression(>, true, ConstantPatternContext.none)
+                                parsePrimary(>, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(>)
+                                    listener: handleLiteralInt(2)
+                            listener: endBinaryExpression(>, 2)
+                        listener: endAssert(assert, Assert.Initializer, (, null, ))
+                      listener: endInitializer())
+                    listener: endInitializers(1, :, ))
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
+                  inPlainSync()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: handleEmptyFunctionBody(;)
+                reportRecoverableError(this, ConstructorWithWrongName)
+                  listener: handleRecoverableError(ConstructorWithWrongName, this, this)
+                listener: endExtensionTypeConstructor(null, this, (, :, ;)
+              listener: endMember()
+            notEofOrType(CLOSE_CURLY_BRACKET, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.ExtensionType, 1, {, })
+          listener: endExtensionTypeDeclaration(extension, null, extension, type, })
+  listener: endTopLevelDeclaration(})
+  reportAllErrorTokens(extension)
+  listener: endCompilationUnit(4, )

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body_error.dart.parser.expect

@@ -0,0 +1,33 @@
+extension type E1(int x) {
+this(this.x) {}
+}
+
+extension type E2(int x) {
+this(this.x) : assert(1 > 2) {}
+}
+
+extension type E3(int x) {
+this(this.x) ;
+}
+
+extension type E4(int x) {
+this(this.x) : assert(1 > 2);
+}
+
+
+extension[KeywordToken] type[StringToken] E1[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E2[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E3[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] ;[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E4[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/declaring_constructors/extension_type_primary_constructor_body_error.dart.scanner.expect

@@ -0,0 +1,33 @@
+extension type E1(int x) {
+this(this.x) {}
+}
+
+extension type E2(int x) {
+this(this.x) : assert(1 > 2) {}
+}
+
+extension type E3(int x) {
+this(this.x) ;
+}
+
+extension type E4(int x) {
+this(this.x) : assert(1 > 2);
+}
+
+
+extension[KeywordToken] type[StringToken] E1[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E2[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken] {[BeginToken]}[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E3[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] ;[SimpleToken]
+}[SimpleToken]
+
+extension[KeywordToken] type[StringToken] E4[StringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+this[KeywordToken]([BeginToken]this[KeywordToken].[SimpleToken]x[StringToken])[SimpleToken] :[SimpleToken] assert[KeywordToken]([BeginToken]1[StringToken] >[SimpleToken] 2[StringToken])[SimpleToken];[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/error_recovery/keyword_named_class_fields.dart.intertwined.expect

@@ -1669,29 +1669,28 @@ parseUnit(class)
                 listener: beginMetadataStar(int)
                 listener: endMetadataStar(0)
               listener: beginMember()
-              recoverFromInvalidMember(int, ;, null, null, null, null, null, null, null, ;, SimpleType(), null, DeclarationKind.Class, WrapperClass)
-                parseFields(;, null, null, null, null, null, null, null, ;, SimpleType(), this, DeclarationKind.Class, WrapperClass, false)
-                  listener: beginFields(DeclarationKind.Class, null, null, null, null, null, null, null, ;)
-                  listener: handleIdentifier(int, typeReference)
-                  listener: handleNoTypeArguments(this)
-                  listener: handleType(int, null)
-                  ensureIdentifierPotentiallyRecovered(int, fieldDeclaration, false)
-                    reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
-                      listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
-                    listener: handleIdentifier(this, fieldDeclaration)
-                  parseFieldInitializerOpt(this, this, null, null, null, null, null, DeclarationKind.Class, WrapperClass)
-                    listener: beginFieldInitializer(=)
-                    parseExpression(=)
-                      looksLikeOuterPatternEquals(=)
-                        skipOuterPattern(=)
-                      parsePrecedenceExpression(=, 1, true, ConstantPatternContext.none)
-                        parseUnaryExpression(=, true, ConstantPatternContext.none)
-                          parsePrimary(=, expression, ConstantPatternContext.none)
-                            parseLiteralInt(=)
-                              listener: handleLiteralInt(42)
-                    listener: endFieldInitializer(=, 42)
-                  listener: endClassFields(null, null, null, null, null, null, null, 1, int, ;)
-                listener: endMember()
+              parseFields(;, null, null, null, null, null, null, null, ;, SimpleType(), this, DeclarationKind.Class, WrapperClass, false)
+                listener: beginFields(DeclarationKind.Class, null, null, null, null, null, null, null, ;)
+                listener: handleIdentifier(int, typeReference)
+                listener: handleNoTypeArguments(this)
+                listener: handleType(int, null)
+                ensureIdentifierPotentiallyRecovered(int, fieldDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, fieldDeclaration)
+                parseFieldInitializerOpt(this, this, null, null, null, null, null, DeclarationKind.Class, WrapperClass)
+                  listener: beginFieldInitializer(=)
+                  parseExpression(=)
+                    looksLikeOuterPatternEquals(=)
+                      skipOuterPattern(=)
+                    parsePrecedenceExpression(=, 1, true, ConstantPatternContext.none)
+                      parseUnaryExpression(=, true, ConstantPatternContext.none)
+                        parsePrimary(=, expression, ConstantPatternContext.none)
+                          parseLiteralInt(=)
+                            listener: handleLiteralInt(42)
+                  listener: endFieldInitializer(=, 42)
+                listener: endClassFields(null, null, null, null, null, null, null, 1, int, ;)
+              listener: endMember()
             notEofOrType(CLOSE_CURLY_BRACKET, int)
             parseClassOrMixinOrExtensionOrEnumMemberImpl(;, DeclarationKind.Class, WrapperClass)
               parseMetadataStar(;)

pkg/front_end/parser_testcases/error_recovery/keyword_named_class_methods.dart.expect

@@ -348,14 +348,6 @@ parser/error_recovery/keyword_named_class_methods:298:7: 'this' can't be used as
   int this(int x) {
       ^^^^
 
-parser/error_recovery/keyword_named_class_methods:298:7: Expected ';' after this.
-  int this(int x) {
-      ^^^^
-
-parser/error_recovery/keyword_named_class_methods:298:11: Expected an identifier, but got '('.
-  int this(int x) {
-          ^
-
 parser/error_recovery/keyword_named_class_methods:303:7: 'throw' can't be used as an identifier because it's a keyword.
   int throw(int x) {
       ^^^^^
@@ -4105,23 +4097,12 @@ beginCompilationUnit(class)
         beginMetadataStar(int)
         endMetadataStar(0)
         beginMember()
-          beginFields(DeclarationKind.Class, null, null, null, null, null, null, null, })
+          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, WrapperClass)
             handleIdentifier(int, typeReference)
             handleNoTypeArguments(this)
             handleType(int, null)
             handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
-            handleIdentifier(this, fieldDeclaration)
-            handleNoFieldInitializer(()
-            handleRecoverableError(Message[Template(ExpectedAfterButGot), Expected ';' after this., null, {string: ;}], this, this)
-          endClassFields(null, null, null, null, null, null, null, 1, int, ;)
-        endMember()
-        beginMetadataStar(()
-        endMetadataStar(0)
-        beginMember()
-          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, (, WrapperClass)
-            handleNoType(;)
-            handleRecoverableError(Message[Template(ExpectedIdentifier), Expected an identifier, but got '('., Try inserting an identifier before '('., {lexeme: (}], (, ()
-            handleIdentifier(, methodDeclaration)
+            handleIdentifier(this, methodDeclaration)
             handleNoTypeVariables(()
             beginFormalParameters((, MemberKind.NonStaticMethod)
               beginMetadataStar(int)
@@ -4170,7 +4151,7 @@ beginCompilationUnit(class)
                 endBinaryExpression(+, 1)
               endReturnStatement(true, return, ;)
             endBlockFunctionBody(2, {, })
-          endClassMethod(null, , (, null, })
+          endClassMethod(null, int, (, null, })
         endMember()
         beginMetadataStar(int)
         endMetadataStar(0)
@@ -4778,7 +4759,7 @@ beginCompilationUnit(class)
             endBlockFunctionBody(2, {, })
           endClassMethod(null, int, (, null, })
         endMember()
-      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 71, {, })
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 70, {, })
     endClassDeclaration(class, })
   endTopLevelDeclaration(})
 endCompilationUnit(1, )

pkg/front_end/parser_testcases/error_recovery/keyword_named_class_methods.dart.intertwined.expect

@@ -8915,163 +8915,138 @@ parseUnit(class)
                 listener: beginMetadataStar(int)
                 listener: endMetadataStar(0)
               listener: beginMember()
-              recoverFromInvalidMember(int, }, null, null, null, null, null, null, null, }, SimpleType(), null, DeclarationKind.Class, WrapperClass)
-                parseFields(}, null, null, null, null, null, null, null, }, SimpleType(), this, DeclarationKind.Class, WrapperClass, false)
-                  listener: beginFields(DeclarationKind.Class, null, null, null, null, null, null, null, })
-                  listener: handleIdentifier(int, typeReference)
-                  listener: handleNoTypeArguments(this)
-                  listener: handleType(int, null)
-                  ensureIdentifierPotentiallyRecovered(int, fieldDeclaration, false)
-                    reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
-                      listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
-                    listener: handleIdentifier(this, fieldDeclaration)
-                  parseFieldInitializerOpt(this, this, null, null, null, null, null, DeclarationKind.Class, WrapperClass)
-                    listener: handleNoFieldInitializer(()
-                  ensureSemicolon(this)
-                    reportRecoverableError(this, Message[Template(ExpectedAfterButGot), Expected ';' after this., null, {string: ;}])
-                      listener: handleRecoverableError(Message[Template(ExpectedAfterButGot), Expected ';' after this., null, {string: ;}], this, this)
-                    rewriter()
-                  listener: endClassFields(null, null, null, null, null, null, null, 1, int, ;)
-                listener: endMember()
-            notEofOrType(CLOSE_CURLY_BRACKET, ()
-            parseClassOrMixinOrExtensionOrEnumMemberImpl(;, DeclarationKind.Class, WrapperClass)
-              parseMetadataStar(;)
-                listener: beginMetadataStar(()
-                listener: endMetadataStar(0)
-              listener: beginMember()
-              recoverFromInvalidMember(;, ;, null, null, null, null, null, null, null, ;, NoType(), null, DeclarationKind.Class, WrapperClass)
-                parseMethod(;, null, null, null, null, null, null, null, ;, NoType(), null, (, DeclarationKind.Class, WrapperClass, false)
-                  listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, (, WrapperClass)
-                  listener: handleNoType(;)
-                  ensureIdentifierPotentiallyRecovered(;, methodDeclaration, false)
-                    insertSyntheticIdentifier(;, methodDeclaration, message: null, messageOnToken: null)
-                      reportRecoverableError((, Message[Template(ExpectedIdentifier), Expected an identifier, but got '('., Try inserting an identifier before '('., {lexeme: (}])
-                        listener: handleRecoverableError(Message[Template(ExpectedIdentifier), Expected an identifier, but got '('., Try inserting an identifier before '('., {lexeme: (}], (, ()
-                      rewriter()
-                    listener: handleIdentifier(, methodDeclaration)
-                  parseQualifiedRestOpt(, methodDeclarationContinuation)
-                  parseMethodTypeVar()
-                    listener: handleNoTypeVariables(()
-                  parseGetterOrFormalParameters(, (, false, MemberKind.NonStaticMethod)
-                    parseFormalParameters(, MemberKind.NonStaticMethod)
-                      parseFormalParametersRest((, MemberKind.NonStaticMethod)
-                        listener: beginFormalParameters((, MemberKind.NonStaticMethod)
-                        parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
-                          parseMetadataStar(()
-                            listener: beginMetadataStar(int)
-                            listener: endMetadataStar(0)
-                          listener: beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
-                          listener: handleIdentifier(int, typeReference)
-                          listener: handleNoTypeArguments(x)
-                          listener: handleType(int, null)
-                          ensureIdentifier(int, formalParameterDeclaration)
-                            listener: handleIdentifier(x, formalParameterDeclaration)
-                          listener: handleFormalParameterWithoutValue())
-                          listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
-                        listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
-                  parseInitializersOpt())
-                    listener: handleNoInitializers()
-                  parseAsyncModifierOpt())
-                    listener: handleAsyncModifier(null, null)
-                    inPlainSync()
+              parseMethod(}, null, null, null, null, null, null, null, }, SimpleType(), null, this, DeclarationKind.Class, WrapperClass, false)
+                listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, WrapperClass)
+                listener: handleIdentifier(int, typeReference)
+                listener: handleNoTypeArguments(this)
+                listener: handleType(int, null)
+                ensureIdentifierPotentiallyRecovered(int, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.NonStaticMethod)
+                  parseFormalParameters(this, MemberKind.NonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.NonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.NonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(int)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
+                        listener: handleIdentifier(int, typeReference)
+                        listener: handleNoTypeArguments(x)
+                        listener: handleType(int, null)
+                        ensureIdentifier(int, formalParameterDeclaration)
+                          listener: handleIdentifier(x, formalParameterDeclaration)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+                parseInitializersOpt())
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
                   inPlainSync()
-                  parseFunctionBody(), false, true)
-                    listener: beginBlockFunctionBody({)
-                    notEofOrType(CLOSE_CURLY_BRACKET, if)
-                    parseStatement({)
-                      parseStatementX({)
-                        parseIfStatement({)
-                          listener: beginIfStatement(if)
-                          ensureParenthesizedCondition(if, allowCase: false)
-                            parseExpressionInParenthesisRest((, allowCase: false)
-                              parseExpression(()
-                                parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
-                                  parseUnaryExpression((, true, ConstantPatternContext.none)
-                                    parsePrimary((, expression, ConstantPatternContext.none)
-                                      parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
-                                        parseSend((, expression, ConstantPatternContext.none)
-                                          ensureIdentifier((, expression)
-                                            listener: handleIdentifier(x, expression)
-                                          listener: handleNoTypeArguments(==)
-                                          parseArgumentsOpt(x)
-                                            listener: handleNoArguments(==)
-                                          listener: handleSend(x, x)
-                                  listener: beginBinaryExpression(==)
-                                  parsePrecedenceExpression(==, 8, true, ConstantPatternContext.none)
-                                    parseUnaryExpression(==, true, ConstantPatternContext.none)
-                                      parsePrimary(==, expression, ConstantPatternContext.none)
-                                        parseLiteralInt(==)
-                                          listener: handleLiteralInt(0)
-                                  listener: endBinaryExpression(==, 0)
-                              ensureCloseParen(0, ()
-                              listener: handleParenthesizedCondition((, null, null)
-                          listener: beginThenStatement(return)
-                          parseStatement())
-                            parseStatementX())
-                              parseReturnStatement())
-                                listener: beginReturnStatement(return)
-                                parseExpression(return)
-                                  parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
-                                    parseUnaryExpression(return, true, ConstantPatternContext.none)
-                                      parsePrimary(return, expression, ConstantPatternContext.none)
-                                        parseLiteralInt(return)
-                                          listener: handleLiteralInt(42)
-                                ensureSemicolon(42)
-                                listener: endReturnStatement(true, return, ;)
-                                inGenerator()
-                          listener: endThenStatement(return, ;)
-                          listener: endIfStatement(if, null, ;)
-                    notEofOrType(CLOSE_CURLY_BRACKET, return)
-                    parseStatement(;)
-                      parseStatementX(;)
-                        parseReturnStatement(;)
-                          listener: beginReturnStatement(return)
-                          parseExpression(return)
-                            parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
-                              parseUnaryExpression(return, true, ConstantPatternContext.none)
-                                parsePrimary(return, expression, ConstantPatternContext.none)
-                                  parseThisExpression(return, expression)
-                                    listener: handleThisExpression(this, expression)
-                                    listener: handleNoTypeArguments(()
-                                    parseArguments(this)
-                                      parseArgumentsRest(()
-                                        listener: beginArguments(()
-                                        allowedToShortcutParseExpression()
-                                        parseExpression(()
-                                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
-                                            parseUnaryExpression((, true, ConstantPatternContext.none)
-                                              parsePrimary((, expression, ConstantPatternContext.none)
-                                                parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
-                                                  parseSend((, expression, ConstantPatternContext.none)
-                                                    ensureIdentifier((, expression)
-                                                      listener: handleIdentifier(x, expression)
-                                                    listener: handleNoTypeArguments(-)
-                                                    parseArgumentsOpt(x)
-                                                      listener: handleNoArguments(-)
-                                                    listener: handleSend(x, x)
-                                            listener: beginBinaryExpression(-)
-                                            parsePrecedenceExpression(-, 14, true, ConstantPatternContext.none)
-                                              parseUnaryExpression(-, true, ConstantPatternContext.none)
-                                                parsePrimary(-, expression, ConstantPatternContext.none)
-                                                  parseLiteralInt(-)
-                                                    listener: handleLiteralInt(1)
-                                            listener: endBinaryExpression(-, 1)
-                                        listener: endArguments(1, (, ))
-                                    listener: handleSend(this, ))
-                              listener: beginBinaryExpression(+)
-                              parsePrecedenceExpression(+, 14, true, ConstantPatternContext.none)
-                                parseUnaryExpression(+, true, ConstantPatternContext.none)
-                                  parsePrimary(+, expression, ConstantPatternContext.none)
-                                    parseLiteralInt(+)
-                                      listener: handleLiteralInt(1)
-                              listener: endBinaryExpression(+, 1)
-                          ensureSemicolon(1)
-                          listener: endReturnStatement(true, return, ;)
-                          inGenerator()
-                    notEofOrType(CLOSE_CURLY_BRACKET, })
-                    listener: endBlockFunctionBody(2, {, })
-                  listener: endClassMethod(null, , (, null, })
-                listener: endMember()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, if)
+                  parseStatement({)
+                    parseStatementX({)
+                      parseIfStatement({)
+                        listener: beginIfStatement(if)
+                        ensureParenthesizedCondition(if, allowCase: false)
+                          parseExpressionInParenthesisRest((, allowCase: false)
+                            parseExpression(()
+                              parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                                parseUnaryExpression((, true, ConstantPatternContext.none)
+                                  parsePrimary((, expression, ConstantPatternContext.none)
+                                    parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
+                                      parseSend((, expression, ConstantPatternContext.none)
+                                        ensureIdentifier((, expression)
+                                          listener: handleIdentifier(x, expression)
+                                        listener: handleNoTypeArguments(==)
+                                        parseArgumentsOpt(x)
+                                          listener: handleNoArguments(==)
+                                        listener: handleSend(x, x)
+                                listener: beginBinaryExpression(==)
+                                parsePrecedenceExpression(==, 8, true, ConstantPatternContext.none)
+                                  parseUnaryExpression(==, true, ConstantPatternContext.none)
+                                    parsePrimary(==, expression, ConstantPatternContext.none)
+                                      parseLiteralInt(==)
+                                        listener: handleLiteralInt(0)
+                                listener: endBinaryExpression(==, 0)
+                            ensureCloseParen(0, ()
+                            listener: handleParenthesizedCondition((, null, null)
+                        listener: beginThenStatement(return)
+                        parseStatement())
+                          parseStatementX())
+                            parseReturnStatement())
+                              listener: beginReturnStatement(return)
+                              parseExpression(return)
+                                parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
+                                  parseUnaryExpression(return, true, ConstantPatternContext.none)
+                                    parsePrimary(return, expression, ConstantPatternContext.none)
+                                      parseLiteralInt(return)
+                                        listener: handleLiteralInt(42)
+                              ensureSemicolon(42)
+                              listener: endReturnStatement(true, return, ;)
+                              inGenerator()
+                        listener: endThenStatement(return, ;)
+                        listener: endIfStatement(if, null, ;)
+                  notEofOrType(CLOSE_CURLY_BRACKET, return)
+                  parseStatement(;)
+                    parseStatementX(;)
+                      parseReturnStatement(;)
+                        listener: beginReturnStatement(return)
+                        parseExpression(return)
+                          parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression(return, true, ConstantPatternContext.none)
+                              parsePrimary(return, expression, ConstantPatternContext.none)
+                                parseThisExpression(return, expression)
+                                  listener: handleThisExpression(this, expression)
+                                  listener: handleNoTypeArguments(()
+                                  parseArguments(this)
+                                    parseArgumentsRest(()
+                                      listener: beginArguments(()
+                                      allowedToShortcutParseExpression()
+                                      parseExpression(()
+                                        parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                                          parseUnaryExpression((, true, ConstantPatternContext.none)
+                                            parsePrimary((, expression, ConstantPatternContext.none)
+                                              parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
+                                                parseSend((, expression, ConstantPatternContext.none)
+                                                  ensureIdentifier((, expression)
+                                                    listener: handleIdentifier(x, expression)
+                                                  listener: handleNoTypeArguments(-)
+                                                  parseArgumentsOpt(x)
+                                                    listener: handleNoArguments(-)
+                                                  listener: handleSend(x, x)
+                                          listener: beginBinaryExpression(-)
+                                          parsePrecedenceExpression(-, 14, true, ConstantPatternContext.none)
+                                            parseUnaryExpression(-, true, ConstantPatternContext.none)
+                                              parsePrimary(-, expression, ConstantPatternContext.none)
+                                                parseLiteralInt(-)
+                                                  listener: handleLiteralInt(1)
+                                          listener: endBinaryExpression(-, 1)
+                                      listener: endArguments(1, (, ))
+                                  listener: handleSend(this, ))
+                            listener: beginBinaryExpression(+)
+                            parsePrecedenceExpression(+, 14, true, ConstantPatternContext.none)
+                              parseUnaryExpression(+, true, ConstantPatternContext.none)
+                                parsePrimary(+, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(+)
+                                    listener: handleLiteralInt(1)
+                            listener: endBinaryExpression(+, 1)
+                        ensureSemicolon(1)
+                        listener: endReturnStatement(true, return, ;)
+                        inGenerator()
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(2, {, })
+                listener: endClassMethod(null, int, (, null, })
+              listener: endMember()
             notEofOrType(CLOSE_CURLY_BRACKET, int)
             parseClassOrMixinOrExtensionOrEnumMemberImpl(}, DeclarationKind.Class, WrapperClass)
               parseMetadataStar(})
@@ -10613,7 +10588,7 @@ parseUnit(class)
                 listener: endClassMethod(null, int, (, null, })
               listener: endMember()
             notEofOrType(CLOSE_CURLY_BRACKET, })
-            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 71, {, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 70, {, })
           listener: endClassDeclaration(class, })
   listener: endTopLevelDeclaration(})
   reportAllErrorTokens(class)

pkg/front_end/parser_testcases/error_recovery/keyword_named_class_methods.dart.parser.expect

@@ -296,7 +296,7 @@ if (x == 0) return 42;
 return sync(x-1) + 1;
 }
 
-int this;*synthetic*(int x) {
+int this(int x) {
 if (x == 0) return 42;
 return this(x-1) + 1;
 }
@@ -644,7 +644,7 @@ if[KeywordToken] ([BeginToken]x[StringToken] ==[SimpleToken] 0[StringToken])[Sim
 return[KeywordToken] sync[KeywordToken]([BeginToken]x[StringToken]-[SimpleToken]1[StringToken])[SimpleToken] +[SimpleToken] 1[StringToken];[SimpleToken]
 }[SimpleToken]
 
-int[StringToken] this[KeywordToken];[SyntheticToken][SyntheticStringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+int[StringToken] this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
 if[KeywordToken] ([BeginToken]x[StringToken] ==[SimpleToken] 0[StringToken])[SimpleToken] return[KeywordToken] 42[StringToken];[SimpleToken]
 return[KeywordToken] this[KeywordToken]([BeginToken]x[StringToken]-[SimpleToken]1[StringToken])[SimpleToken] +[SimpleToken] 1[StringToken];[SimpleToken]
 }[SimpleToken]

pkg/front_end/parser_testcases/error_recovery/keyword_named_class_methods_2.dart.expect

@@ -336,14 +336,6 @@ parser/error_recovery/keyword_named_class_methods_2:297:7: 'this' can't be used
   int this(int x) {
       ^^^^
 
-parser/error_recovery/keyword_named_class_methods_2:297:7: Expected ';' after this.
-  int this(int x) {
-      ^^^^
-
-parser/error_recovery/keyword_named_class_methods_2:297:11: Expected an identifier, but got '('.
-  int this(int x) {
-          ^
-
 parser/error_recovery/keyword_named_class_methods_2:302:7: 'throw' can't be used as an identifier because it's a keyword.
   int throw(int x) {
       ^^^^^
@@ -4081,23 +4073,12 @@ beginCompilationUnit(class)
         beginMetadataStar(int)
         endMetadataStar(0)
         beginMember()
-          beginFields(DeclarationKind.Class, null, null, null, null, null, null, null, })
+          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, WrapperClass)
             handleIdentifier(int, typeReference)
             handleNoTypeArguments(this)
             handleType(int, null)
             handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
-            handleIdentifier(this, fieldDeclaration)
-            handleNoFieldInitializer(()
-            handleRecoverableError(Message[Template(ExpectedAfterButGot), Expected ';' after this., null, {string: ;}], this, this)
-          endClassFields(null, null, null, null, null, null, null, 1, int, ;)
-        endMember()
-        beginMetadataStar(()
-        endMetadataStar(0)
-        beginMember()
-          beginMethod(DeclarationKind.Class, null, null, null, null, null, null, (, WrapperClass)
-            handleNoType(;)
-            handleRecoverableError(Message[Template(ExpectedIdentifier), Expected an identifier, but got '('., Try inserting an identifier before '('., {lexeme: (}], (, ()
-            handleIdentifier(, methodDeclaration)
+            handleIdentifier(this, methodDeclaration)
             handleNoTypeVariables(()
             beginFormalParameters((, MemberKind.NonStaticMethod)
               beginMetadataStar(int)
@@ -4146,7 +4127,7 @@ beginCompilationUnit(class)
                 endBinaryExpression(+, 1)
               endReturnStatement(true, return, ;)
             endBlockFunctionBody(2, {, })
-          endClassMethod(null, , (, null, })
+          endClassMethod(null, int, (, null, })
         endMember()
         beginMetadataStar(int)
         endMetadataStar(0)
@@ -4754,7 +4735,7 @@ beginCompilationUnit(class)
             endBlockFunctionBody(2, {, })
           endClassMethod(null, int, (, null, })
         endMember()
-      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 71, {, })
+      endClassOrMixinOrExtensionBody(DeclarationKind.Class, 70, {, })
     endClassDeclaration(class, })
   endTopLevelDeclaration(})
 endCompilationUnit(1, )

pkg/front_end/parser_testcases/error_recovery/keyword_named_class_methods_2.dart.intertwined.expect

@@ -9518,173 +9518,148 @@ parseUnit(class)
                 listener: beginMetadataStar(int)
                 listener: endMetadataStar(0)
               listener: beginMember()
-              recoverFromInvalidMember(int, }, null, null, null, null, null, null, null, }, SimpleType(), null, DeclarationKind.Class, WrapperClass)
-                parseFields(}, null, null, null, null, null, null, null, }, SimpleType(), this, DeclarationKind.Class, WrapperClass, false)
-                  listener: beginFields(DeclarationKind.Class, null, null, null, null, null, null, null, })
-                  listener: handleIdentifier(int, typeReference)
-                  listener: handleNoTypeArguments(this)
-                  listener: handleType(int, null)
-                  ensureIdentifierPotentiallyRecovered(int, fieldDeclaration, false)
-                    reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
-                      listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
-                    listener: handleIdentifier(this, fieldDeclaration)
-                  parseFieldInitializerOpt(this, this, null, null, null, null, null, DeclarationKind.Class, WrapperClass)
-                    listener: handleNoFieldInitializer(()
-                  ensureSemicolon(this)
-                    reportRecoverableError(this, Message[Template(ExpectedAfterButGot), Expected ';' after this., null, {string: ;}])
-                      listener: handleRecoverableError(Message[Template(ExpectedAfterButGot), Expected ';' after this., null, {string: ;}], this, this)
-                    rewriter()
-                  listener: endClassFields(null, null, null, null, null, null, null, 1, int, ;)
-                listener: endMember()
-            notEofOrType(CLOSE_CURLY_BRACKET, ()
-            parseClassOrMixinOrExtensionOrEnumMemberImpl(;, DeclarationKind.Class, WrapperClass)
-              parseMetadataStar(;)
-                listener: beginMetadataStar(()
-                listener: endMetadataStar(0)
-              listener: beginMember()
-              recoverFromInvalidMember(;, ;, null, null, null, null, null, null, null, ;, NoType(), null, DeclarationKind.Class, WrapperClass)
-                parseMethod(;, null, null, null, null, null, null, null, ;, NoType(), null, (, DeclarationKind.Class, WrapperClass, false)
-                  listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, (, WrapperClass)
-                  listener: handleNoType(;)
-                  ensureIdentifierPotentiallyRecovered(;, methodDeclaration, false)
-                    insertSyntheticIdentifier(;, methodDeclaration, message: null, messageOnToken: null)
-                      reportRecoverableError((, Message[Template(ExpectedIdentifier), Expected an identifier, but got '('., Try inserting an identifier before '('., {lexeme: (}])
-                        listener: handleRecoverableError(Message[Template(ExpectedIdentifier), Expected an identifier, but got '('., Try inserting an identifier before '('., {lexeme: (}], (, ()
-                      rewriter()
-                    listener: handleIdentifier(, methodDeclaration)
-                  parseQualifiedRestOpt(, methodDeclarationContinuation)
-                  parseMethodTypeVar()
-                    listener: handleNoTypeVariables(()
-                  parseGetterOrFormalParameters(, (, false, MemberKind.NonStaticMethod)
-                    parseFormalParameters(, MemberKind.NonStaticMethod)
-                      parseFormalParametersRest((, MemberKind.NonStaticMethod)
-                        listener: beginFormalParameters((, MemberKind.NonStaticMethod)
-                        parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
-                          parseMetadataStar(()
-                            listener: beginMetadataStar(int)
-                            listener: endMetadataStar(0)
-                          listener: beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
-                          listener: handleIdentifier(int, typeReference)
-                          listener: handleNoTypeArguments(x)
-                          listener: handleType(int, null)
-                          ensureIdentifier(int, formalParameterDeclaration)
-                            listener: handleIdentifier(x, formalParameterDeclaration)
-                          listener: handleFormalParameterWithoutValue())
-                          listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
-                        listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
-                  parseInitializersOpt())
-                    listener: handleNoInitializers()
-                  parseAsyncModifierOpt())
-                    listener: handleAsyncModifier(null, null)
-                    inPlainSync()
+              parseMethod(}, null, null, null, null, null, null, null, }, SimpleType(), null, this, DeclarationKind.Class, WrapperClass, false)
+                listener: beginMethod(DeclarationKind.Class, null, null, null, null, null, null, this, WrapperClass)
+                listener: handleIdentifier(int, typeReference)
+                listener: handleNoTypeArguments(this)
+                listener: handleType(int, null)
+                ensureIdentifierPotentiallyRecovered(int, methodDeclaration, false)
+                  reportRecoverableErrorWithToken(this, Template(ExpectedIdentifierButGotKeyword))
+                    listener: handleRecoverableError(Message[Template(ExpectedIdentifierButGotKeyword), 'this' can't be used as an identifier because it's a keyword., Try renaming this to be an identifier that isn't a keyword., {lexeme: this}], this, this)
+                  listener: handleIdentifier(this, methodDeclaration)
+                parseQualifiedRestOpt(this, methodDeclarationContinuation)
+                parseMethodTypeVar(this)
+                  listener: handleNoTypeVariables(()
+                parseGetterOrFormalParameters(this, this, false, MemberKind.NonStaticMethod)
+                  parseFormalParameters(this, MemberKind.NonStaticMethod)
+                    parseFormalParametersRest((, MemberKind.NonStaticMethod)
+                      listener: beginFormalParameters((, MemberKind.NonStaticMethod)
+                      parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(int)
+                          listener: endMetadataStar(0)
+                        listener: beginFormalParameter(int, MemberKind.NonStaticMethod, null, null, null)
+                        listener: handleIdentifier(int, typeReference)
+                        listener: handleNoTypeArguments(x)
+                        listener: handleType(int, null)
+                        ensureIdentifier(int, formalParameterDeclaration)
+                          listener: handleIdentifier(x, formalParameterDeclaration)
+                        listener: handleFormalParameterWithoutValue())
+                        listener: endFormalParameter(null, null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.NonStaticMethod)
+                      listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+                parseInitializersOpt())
+                  listener: handleNoInitializers()
+                parseAsyncModifierOpt())
+                  listener: handleAsyncModifier(null, null)
                   inPlainSync()
-                  parseFunctionBody(), false, true)
-                    listener: beginBlockFunctionBody({)
-                    notEofOrType(CLOSE_CURLY_BRACKET, if)
-                    parseStatement({)
-                      parseStatementX({)
-                        parseIfStatement({)
-                          listener: beginIfStatement(if)
-                          ensureParenthesizedCondition(if, allowCase: true)
-                            parseExpressionInParenthesisRest((, allowCase: true)
-                              parseExpression(()
-                                looksLikeOuterPatternEquals(()
-                                  skipOuterPattern(()
-                                    skipObjectPatternRest(x)
-                                parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
-                                  parseUnaryExpression((, true, ConstantPatternContext.none)
-                                    parsePrimary((, expression, ConstantPatternContext.none)
-                                      parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
-                                        parseSend((, expression, ConstantPatternContext.none)
-                                          ensureIdentifier((, expression)
-                                            listener: handleIdentifier(x, expression)
-                                          listener: handleNoTypeArguments(==)
-                                          parseArgumentsOpt(x)
-                                            listener: handleNoArguments(==)
-                                          listener: handleSend(x, x)
-                                  listener: beginBinaryExpression(==)
-                                  parsePrecedenceExpression(==, 8, true, ConstantPatternContext.none)
-                                    parseUnaryExpression(==, true, ConstantPatternContext.none)
-                                      parsePrimary(==, expression, ConstantPatternContext.none)
-                                        parseLiteralInt(==)
-                                          listener: handleLiteralInt(0)
-                                  listener: endBinaryExpression(==, 0)
-                              ensureCloseParen(0, ()
-                              listener: handleParenthesizedCondition((, null, null)
-                          listener: beginThenStatement(return)
-                          parseStatement())
-                            parseStatementX())
-                              parseReturnStatement())
-                                listener: beginReturnStatement(return)
-                                parseExpression(return)
-                                  looksLikeOuterPatternEquals(return)
-                                    skipOuterPattern(return)
-                                  parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
-                                    parseUnaryExpression(return, true, ConstantPatternContext.none)
-                                      parsePrimary(return, expression, ConstantPatternContext.none)
-                                        parseLiteralInt(return)
-                                          listener: handleLiteralInt(42)
-                                ensureSemicolon(42)
-                                listener: endReturnStatement(true, return, ;)
-                                inGenerator()
-                          listener: endThenStatement(return, ;)
-                          listener: endIfStatement(if, null, ;)
-                    notEofOrType(CLOSE_CURLY_BRACKET, return)
-                    parseStatement(;)
-                      parseStatementX(;)
-                        parseReturnStatement(;)
-                          listener: beginReturnStatement(return)
-                          parseExpression(return)
-                            looksLikeOuterPatternEquals(return)
-                              skipOuterPattern(return)
-                            parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
-                              parseUnaryExpression(return, true, ConstantPatternContext.none)
-                                parsePrimary(return, expression, ConstantPatternContext.none)
-                                  parseThisExpression(return, expression)
-                                    listener: handleThisExpression(this, expression)
-                                    listener: handleNoTypeArguments(()
-                                    parseArguments(this)
-                                      parseArgumentsRest(()
-                                        listener: beginArguments(()
-                                        allowedToShortcutParseExpression()
-                                        parseExpression(()
-                                          looksLikeOuterPatternEquals(()
-                                            skipOuterPattern(()
-                                              skipObjectPatternRest(x)
-                                          parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
-                                            parseUnaryExpression((, true, ConstantPatternContext.none)
-                                              parsePrimary((, expression, ConstantPatternContext.none)
-                                                parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
-                                                  parseSend((, expression, ConstantPatternContext.none)
-                                                    ensureIdentifier((, expression)
-                                                      listener: handleIdentifier(x, expression)
-                                                    listener: handleNoTypeArguments(-)
-                                                    parseArgumentsOpt(x)
-                                                      listener: handleNoArguments(-)
-                                                    listener: handleSend(x, x)
-                                            listener: beginBinaryExpression(-)
-                                            parsePrecedenceExpression(-, 14, true, ConstantPatternContext.none)
-                                              parseUnaryExpression(-, true, ConstantPatternContext.none)
-                                                parsePrimary(-, expression, ConstantPatternContext.none)
-                                                  parseLiteralInt(-)
-                                                    listener: handleLiteralInt(1)
-                                            listener: endBinaryExpression(-, 1)
-                                        listener: endArguments(1, (, ))
-                                    listener: handleSend(this, ))
-                              listener: beginBinaryExpression(+)
-                              parsePrecedenceExpression(+, 14, true, ConstantPatternContext.none)
-                                parseUnaryExpression(+, true, ConstantPatternContext.none)
-                                  parsePrimary(+, expression, ConstantPatternContext.none)
-                                    parseLiteralInt(+)
-                                      listener: handleLiteralInt(1)
-                              listener: endBinaryExpression(+, 1)
-                          ensureSemicolon(1)
-                          listener: endReturnStatement(true, return, ;)
-                          inGenerator()
-                    notEofOrType(CLOSE_CURLY_BRACKET, })
-                    listener: endBlockFunctionBody(2, {, })
-                  listener: endClassMethod(null, , (, null, })
-                listener: endMember()
+                inPlainSync()
+                parseFunctionBody(), false, true)
+                  listener: beginBlockFunctionBody({)
+                  notEofOrType(CLOSE_CURLY_BRACKET, if)
+                  parseStatement({)
+                    parseStatementX({)
+                      parseIfStatement({)
+                        listener: beginIfStatement(if)
+                        ensureParenthesizedCondition(if, allowCase: true)
+                          parseExpressionInParenthesisRest((, allowCase: true)
+                            parseExpression(()
+                              looksLikeOuterPatternEquals(()
+                                skipOuterPattern(()
+                                  skipObjectPatternRest(x)
+                              parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                                parseUnaryExpression((, true, ConstantPatternContext.none)
+                                  parsePrimary((, expression, ConstantPatternContext.none)
+                                    parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
+                                      parseSend((, expression, ConstantPatternContext.none)
+                                        ensureIdentifier((, expression)
+                                          listener: handleIdentifier(x, expression)
+                                        listener: handleNoTypeArguments(==)
+                                        parseArgumentsOpt(x)
+                                          listener: handleNoArguments(==)
+                                        listener: handleSend(x, x)
+                                listener: beginBinaryExpression(==)
+                                parsePrecedenceExpression(==, 8, true, ConstantPatternContext.none)
+                                  parseUnaryExpression(==, true, ConstantPatternContext.none)
+                                    parsePrimary(==, expression, ConstantPatternContext.none)
+                                      parseLiteralInt(==)
+                                        listener: handleLiteralInt(0)
+                                listener: endBinaryExpression(==, 0)
+                            ensureCloseParen(0, ()
+                            listener: handleParenthesizedCondition((, null, null)
+                        listener: beginThenStatement(return)
+                        parseStatement())
+                          parseStatementX())
+                            parseReturnStatement())
+                              listener: beginReturnStatement(return)
+                              parseExpression(return)
+                                looksLikeOuterPatternEquals(return)
+                                  skipOuterPattern(return)
+                                parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
+                                  parseUnaryExpression(return, true, ConstantPatternContext.none)
+                                    parsePrimary(return, expression, ConstantPatternContext.none)
+                                      parseLiteralInt(return)
+                                        listener: handleLiteralInt(42)
+                              ensureSemicolon(42)
+                              listener: endReturnStatement(true, return, ;)
+                              inGenerator()
+                        listener: endThenStatement(return, ;)
+                        listener: endIfStatement(if, null, ;)
+                  notEofOrType(CLOSE_CURLY_BRACKET, return)
+                  parseStatement(;)
+                    parseStatementX(;)
+                      parseReturnStatement(;)
+                        listener: beginReturnStatement(return)
+                        parseExpression(return)
+                          looksLikeOuterPatternEquals(return)
+                            skipOuterPattern(return)
+                          parsePrecedenceExpression(return, 1, true, ConstantPatternContext.none)
+                            parseUnaryExpression(return, true, ConstantPatternContext.none)
+                              parsePrimary(return, expression, ConstantPatternContext.none)
+                                parseThisExpression(return, expression)
+                                  listener: handleThisExpression(this, expression)
+                                  listener: handleNoTypeArguments(()
+                                  parseArguments(this)
+                                    parseArgumentsRest(()
+                                      listener: beginArguments(()
+                                      allowedToShortcutParseExpression()
+                                      parseExpression(()
+                                        looksLikeOuterPatternEquals(()
+                                          skipOuterPattern(()
+                                            skipObjectPatternRest(x)
+                                        parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                                          parseUnaryExpression((, true, ConstantPatternContext.none)
+                                            parsePrimary((, expression, ConstantPatternContext.none)
+                                              parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
+                                                parseSend((, expression, ConstantPatternContext.none)
+                                                  ensureIdentifier((, expression)
+                                                    listener: handleIdentifier(x, expression)
+                                                  listener: handleNoTypeArguments(-)
+                                                  parseArgumentsOpt(x)
+                                                    listener: handleNoArguments(-)
+                                                  listener: handleSend(x, x)
+                                          listener: beginBinaryExpression(-)
+                                          parsePrecedenceExpression(-, 14, true, ConstantPatternContext.none)
+                                            parseUnaryExpression(-, true, ConstantPatternContext.none)
+                                              parsePrimary(-, expression, ConstantPatternContext.none)
+                                                parseLiteralInt(-)
+                                                  listener: handleLiteralInt(1)
+                                          listener: endBinaryExpression(-, 1)
+                                      listener: endArguments(1, (, ))
+                                  listener: handleSend(this, ))
+                            listener: beginBinaryExpression(+)
+                            parsePrecedenceExpression(+, 14, true, ConstantPatternContext.none)
+                              parseUnaryExpression(+, true, ConstantPatternContext.none)
+                                parsePrimary(+, expression, ConstantPatternContext.none)
+                                  parseLiteralInt(+)
+                                    listener: handleLiteralInt(1)
+                            listener: endBinaryExpression(+, 1)
+                        ensureSemicolon(1)
+                        listener: endReturnStatement(true, return, ;)
+                        inGenerator()
+                  notEofOrType(CLOSE_CURLY_BRACKET, })
+                  listener: endBlockFunctionBody(2, {, })
+                listener: endClassMethod(null, int, (, null, })
+              listener: endMember()
             notEofOrType(CLOSE_CURLY_BRACKET, int)
             parseClassOrMixinOrExtensionOrEnumMemberImpl(}, DeclarationKind.Class, WrapperClass)
               parseMetadataStar(})
@@ -11333,7 +11308,7 @@ parseUnit(class)
                 listener: endClassMethod(null, int, (, null, })
               listener: endMember()
             notEofOrType(CLOSE_CURLY_BRACKET, })
-            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 71, {, })
+            listener: endClassOrMixinOrExtensionBody(DeclarationKind.Class, 70, {, })
           listener: endClassDeclaration(class, })
   listener: endTopLevelDeclaration(})
   reportAllErrorTokens(class)

pkg/front_end/parser_testcases/error_recovery/keyword_named_class_methods_2.dart.parser.expect

@@ -296,7 +296,7 @@ if (x == 0) return 42;
 return sync(x-1) + 1;
 }
 
-int this;*synthetic*(int x) {
+int this(int x) {
 if (x == 0) return 42;
 return this(x-1) + 1;
 }
@@ -644,7 +644,7 @@ if[KeywordToken] ([BeginToken]x[StringToken] ==[SimpleToken] 0[StringToken])[Sim
 return[KeywordToken] sync[KeywordToken]([BeginToken]x[StringToken]-[SimpleToken]1[StringToken])[SimpleToken] +[SimpleToken] 1[StringToken];[SimpleToken]
 }[SimpleToken]
 
-int[StringToken] this[KeywordToken];[SyntheticToken][SyntheticStringToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
+int[StringToken] this[KeywordToken]([BeginToken]int[StringToken] x[StringToken])[SimpleToken] {[BeginToken]
 if[KeywordToken] ([BeginToken]x[StringToken] ==[SimpleToken] 0[StringToken])[SimpleToken] return[KeywordToken] 42[StringToken];[SimpleToken]
 return[KeywordToken] this[KeywordToken]([BeginToken]x[StringToken]-[SimpleToken]1[StringToken])[SimpleToken] +[SimpleToken] 1[StringToken];[SimpleToken]
 }[SimpleToken]

pkg/front_end/test/parser/parser_ast_test.dart

@@ -704,6 +704,15 @@ List<String> processItem(ParserAstNode item, List<int> data) {
           decl.endToken.offset + decl.endToken.length,
         ),
       ];
+    } else if (item.isPrimaryConstructorBody()) {
+      PrimaryConstructorBodyEnd decl = item.getPrimaryConstructorBody();
+      return [
+        getCutContent(
+          data,
+          decl.beginToken.offset,
+          decl.endToken.offset + decl.endToken.length,
+        ),
+      ];
     } else {
       if (item.type == ParserAstType.BEGIN) return const [];
       if (item.type == ParserAstType.HANDLE) return const [];

pkg/front_end/test/parser_test_listener.dart

@@ -596,6 +596,34 @@ class ParserTestListener implements Listener {
     );
   }
 
+  @override
+  void beginPrimaryConstructorBody(Token token) {
+    seen(token);
+    doPrint(
+      'beginPrimaryConstructorBody('
+      '$token)',
+    );
+    indent++;
+  }
+
+  @override
+  void endPrimaryConstructorBody(
+    Token beginToken,
+    Token? beginInitializers,
+    Token endToken,
+  ) {
+    indent--;
+    seen(beginToken);
+    seen(beginInitializers);
+    seen(endToken);
+    doPrint(
+      'endPrimaryConstructorBody('
+      '$beginToken, '
+      '$beginInitializers, '
+      '$endToken)',
+    );
+  }
+
   @override
   void beginCombinators(Token token) {
     seen(token);

pkg/front_end/test/parser_test_parser.dart

@@ -1235,6 +1235,18 @@ class TestParser extends Parser {
     return result;
   }
 
+  @override
+  Token parsePrimaryConstructorBody(Token token) {
+    doPrint(
+      'parsePrimaryConstructorBody('
+      '$token)',
+    );
+    indent++;
+    var result = super.parsePrimaryConstructorBody(token);
+    indent--;
+    return result;
+  }
+
   @override
   Token parseExtensionTypeDeclaration(
     Token beginToken,

pkg/front_end/testcases/general/issue43363.dart.strong.expect

@@ -2,45 +2,91 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Expected a class member, but got 'this'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: 'this' can't be used as an identifier because it's a keyword.
+// Try renaming this to be an identifier that isn't a keyword.
 //         this.y = 2;
 //         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:13: Error: Expected a class member, but got '.'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: A method declaration needs an explicit list of parameters.
+// Try adding a parameter list to the method declaration.
 //         this.y = 2;
-//             ^
+//         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: Variables must be declared using the keywords 'const', 'final', 'var' or a type name.
-// Try adding the name of the type of the variable or the keyword 'var'.
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Only factory constructor can specify '=' redirection.
+// Try making this a factory constructor, or remove the redirection.
 //         this.y = 2;
-//              ^
+//                ^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: 'y' is already declared in this scope.
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected an identifier, but got '2'.
+// Try inserting an identifier before '2'.
 //         this.y = 2;
-//              ^
-// pkg/front_end/testcases/general/issue43363.dart:7:13: Context: Previous declaration of 'y'.
-//   final int y;
-//             ^
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Expected ';' after this.
+//         this.y = 2;
+//                ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: The name of a constructor must match the name of the enclosing class.
+//         this.y = 2;
+//         ^^^^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected a class member, but got '2'.
+//         this.y = 2;
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:19: Error: Expected a class member, but got ';'.
+//         this.y = 2;
+//                   ^
 //
 // pkg/front_end/testcases/general/issue43363.dart:9:16: Error: A redirecting constructor can't have other initializers.
 //         this.x = 1;
 //                ^
 //
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Expected a function body or '=>'.
+// Try adding {}.
+//         this.y = 2;
+//                ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Constructors can't have a return type.
+// Try removing the return type.
+//         this.y = 2;
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Final field 'x' is not initialized by this constructor.
+// Try to initialize the field using an initializing formal or a field initializer.
+//         this.y = 2;
+//         ^
+// pkg/front_end/testcases/general/issue43363.dart:6:13: Context: 'x' is defined here.
+//   final int x;
+//             ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Final field 'y' is not initialized by this constructor.
+// Try to initialize the field using an initializing formal or a field initializer.
+//         this.y = 2;
+//         ^
+// pkg/front_end/testcases/general/issue43363.dart:7:13: Context: 'y' is defined here.
+//   final int y;
+//             ^
+//
 import self as self;
 import "dart:core" as core;
 
 class E extends core::Object {
   final field core::int x;
   final field core::int y;
+  erroneous constructor y() → self::E
+    : self::E::y = null, self::E::x = null, super core::Object::•()
+    invalid-expression "pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Constructors can't have a return type.
+Try removing the return type.
+        this.y = 2;
+                 ^";
   erroneous constructor •() → self::E
     : final dynamic #t1 = invalid-expression "pkg/front_end/testcases/general/issue43363.dart:9:16: Error: A redirecting constructor can't have other initializers.
         this.x = 1;
                ^", this self::E::named()
     ;
   constructor named() → self::E
-    : self::E::x = 5, final dynamic #t2 = invalid-expression "pkg/front_end/testcases/general/issue43363.dart:13:20: Error: Can't use 'y' because it is declared more than once.
-              this.y = 6;
-                   ^"
+    : self::E::x = 5, self::E::y = 6, super core::Object::•()
     ;
 }
 static method main() → dynamic {}

pkg/front_end/testcases/general/issue43363.dart.strong.modular.expect

@@ -2,45 +2,91 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Expected a class member, but got 'this'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: 'this' can't be used as an identifier because it's a keyword.
+// Try renaming this to be an identifier that isn't a keyword.
 //         this.y = 2;
 //         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:13: Error: Expected a class member, but got '.'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: A method declaration needs an explicit list of parameters.
+// Try adding a parameter list to the method declaration.
 //         this.y = 2;
-//             ^
+//         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: Variables must be declared using the keywords 'const', 'final', 'var' or a type name.
-// Try adding the name of the type of the variable or the keyword 'var'.
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Only factory constructor can specify '=' redirection.
+// Try making this a factory constructor, or remove the redirection.
 //         this.y = 2;
-//              ^
+//                ^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: 'y' is already declared in this scope.
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected an identifier, but got '2'.
+// Try inserting an identifier before '2'.
 //         this.y = 2;
-//              ^
-// pkg/front_end/testcases/general/issue43363.dart:7:13: Context: Previous declaration of 'y'.
-//   final int y;
-//             ^
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Expected ';' after this.
+//         this.y = 2;
+//                ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: The name of a constructor must match the name of the enclosing class.
+//         this.y = 2;
+//         ^^^^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected a class member, but got '2'.
+//         this.y = 2;
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:19: Error: Expected a class member, but got ';'.
+//         this.y = 2;
+//                   ^
 //
 // pkg/front_end/testcases/general/issue43363.dart:9:16: Error: A redirecting constructor can't have other initializers.
 //         this.x = 1;
 //                ^
 //
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Expected a function body or '=>'.
+// Try adding {}.
+//         this.y = 2;
+//                ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Constructors can't have a return type.
+// Try removing the return type.
+//         this.y = 2;
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Final field 'x' is not initialized by this constructor.
+// Try to initialize the field using an initializing formal or a field initializer.
+//         this.y = 2;
+//         ^
+// pkg/front_end/testcases/general/issue43363.dart:6:13: Context: 'x' is defined here.
+//   final int x;
+//             ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Final field 'y' is not initialized by this constructor.
+// Try to initialize the field using an initializing formal or a field initializer.
+//         this.y = 2;
+//         ^
+// pkg/front_end/testcases/general/issue43363.dart:7:13: Context: 'y' is defined here.
+//   final int y;
+//             ^
+//
 import self as self;
 import "dart:core" as core;
 
 class E extends core::Object {
   final field core::int x;
   final field core::int y;
+  erroneous constructor y() → self::E
+    : self::E::y = null, self::E::x = null, super core::Object::•()
+    invalid-expression "pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Constructors can't have a return type.
+Try removing the return type.
+        this.y = 2;
+                 ^";
   erroneous constructor •() → self::E
     : final dynamic #t1 = invalid-expression "pkg/front_end/testcases/general/issue43363.dart:9:16: Error: A redirecting constructor can't have other initializers.
         this.x = 1;
                ^", this self::E::named()
     ;
   constructor named() → self::E
-    : self::E::x = 5, final dynamic #t2 = invalid-expression "pkg/front_end/testcases/general/issue43363.dart:13:20: Error: Can't use 'y' because it is declared more than once.
-              this.y = 6;
-                   ^"
+    : self::E::x = 5, self::E::y = 6, super core::Object::•()
     ;
 }
 static method main() → dynamic {}

pkg/front_end/testcases/general/issue43363.dart.strong.outline.expect

@@ -2,25 +2,41 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Expected a class member, but got 'this'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: 'this' can't be used as an identifier because it's a keyword.
+// Try renaming this to be an identifier that isn't a keyword.
 //         this.y = 2;
 //         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:13: Error: Expected a class member, but got '.'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: A method declaration needs an explicit list of parameters.
+// Try adding a parameter list to the method declaration.
 //         this.y = 2;
-//             ^
+//         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: Variables must be declared using the keywords 'const', 'final', 'var' or a type name.
-// Try adding the name of the type of the variable or the keyword 'var'.
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Only factory constructor can specify '=' redirection.
+// Try making this a factory constructor, or remove the redirection.
 //         this.y = 2;
-//              ^
+//                ^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: 'y' is already declared in this scope.
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected an identifier, but got '2'.
+// Try inserting an identifier before '2'.
 //         this.y = 2;
-//              ^
-// pkg/front_end/testcases/general/issue43363.dart:7:13: Context: Previous declaration of 'y'.
-//   final int y;
-//             ^
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Expected ';' after this.
+//         this.y = 2;
+//                ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: The name of a constructor must match the name of the enclosing class.
+//         this.y = 2;
+//         ^^^^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected a class member, but got '2'.
+//         this.y = 2;
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:19: Error: Expected a class member, but got ';'.
+//         this.y = 2;
+//                   ^
 //
 import self as self;
 import "dart:core" as core;
@@ -28,6 +44,8 @@ import "dart:core" as core;
 class E extends core::Object {
   final field core::int x;
   final field core::int y;
+  constructor y() → self::E
+    ;
   constructor •() → self::E
     ;
   constructor named() → self::E

pkg/front_end/testcases/general/issue43363.dart.strong.transformed.expect

@@ -2,45 +2,91 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Expected a class member, but got 'this'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: 'this' can't be used as an identifier because it's a keyword.
+// Try renaming this to be an identifier that isn't a keyword.
 //         this.y = 2;
 //         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:13: Error: Expected a class member, but got '.'.
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: A method declaration needs an explicit list of parameters.
+// Try adding a parameter list to the method declaration.
 //         this.y = 2;
-//             ^
+//         ^^^^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: Variables must be declared using the keywords 'const', 'final', 'var' or a type name.
-// Try adding the name of the type of the variable or the keyword 'var'.
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Only factory constructor can specify '=' redirection.
+// Try making this a factory constructor, or remove the redirection.
 //         this.y = 2;
-//              ^
+//                ^
 //
-// pkg/front_end/testcases/general/issue43363.dart:10:14: Error: 'y' is already declared in this scope.
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected an identifier, but got '2'.
+// Try inserting an identifier before '2'.
 //         this.y = 2;
-//              ^
-// pkg/front_end/testcases/general/issue43363.dart:7:13: Context: Previous declaration of 'y'.
-//   final int y;
-//             ^
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Expected ';' after this.
+//         this.y = 2;
+//                ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: The name of a constructor must match the name of the enclosing class.
+//         this.y = 2;
+//         ^^^^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Expected a class member, but got '2'.
+//         this.y = 2;
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:19: Error: Expected a class member, but got ';'.
+//         this.y = 2;
+//                   ^
 //
 // pkg/front_end/testcases/general/issue43363.dart:9:16: Error: A redirecting constructor can't have other initializers.
 //         this.x = 1;
 //                ^
 //
+// pkg/front_end/testcases/general/issue43363.dart:10:16: Error: Expected a function body or '=>'.
+// Try adding {}.
+//         this.y = 2;
+//                ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Constructors can't have a return type.
+// Try removing the return type.
+//         this.y = 2;
+//                  ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Final field 'x' is not initialized by this constructor.
+// Try to initialize the field using an initializing formal or a field initializer.
+//         this.y = 2;
+//         ^
+// pkg/front_end/testcases/general/issue43363.dart:6:13: Context: 'x' is defined here.
+//   final int x;
+//             ^
+//
+// pkg/front_end/testcases/general/issue43363.dart:10:9: Error: Final field 'y' is not initialized by this constructor.
+// Try to initialize the field using an initializing formal or a field initializer.
+//         this.y = 2;
+//         ^
+// pkg/front_end/testcases/general/issue43363.dart:7:13: Context: 'y' is defined here.
+//   final int y;
+//             ^
+//
 import self as self;
 import "dart:core" as core;
 
 class E extends core::Object {
   final field core::int x;
   final field core::int y;
+  erroneous constructor y() → self::E
+    : self::E::y = null, self::E::x = null, super core::Object::•()
+    invalid-expression "pkg/front_end/testcases/general/issue43363.dart:10:18: Error: Constructors can't have a return type.
+Try removing the return type.
+        this.y = 2;
+                 ^";
   erroneous constructor •() → self::E
     : final dynamic #t1 = invalid-expression "pkg/front_end/testcases/general/issue43363.dart:9:16: Error: A redirecting constructor can't have other initializers.
         this.x = 1;
                ^", this self::E::named()
     ;
   constructor named() → self::E
-    : self::E::x = 5, final dynamic #t2 = invalid-expression "pkg/front_end/testcases/general/issue43363.dart:13:20: Error: Can't use 'y' because it is declared more than once.
-              this.y = 6;
-                   ^"
+    : self::E::x = 5, self::E::y = 6, super core::Object::•()
     ;
 }
 static method main() → dynamic {}

pkg/front_end/testcases/general/issue43363.dart.textual_outline.expect

@@ -2,8 +2,8 @@ class E {
   final int x;
   final int y;
   E() : this.named(), this.x = 1;
-  this.
-  y = 2;
+  this.y ()= ;
+  2;
   E.named() : this.x = 5, this.y = 6;
 }