Extension type. Issue 53625. Report REPRESENTATION_FIELD_TRAILING_COMMA.

Bug: #53625
Change-Id: I89d34b35b3e8b5977d1f99d550f91ce58e1c2150
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/328340
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>

Author: scheglov

pkg/analysis_server/lib/src/services/correction/error_fix_status.yaml

@@ -3210,6 +3210,10 @@ ParserErrorCode.REDIRECTION_IN_NON_FACTORY_CONSTRUCTOR:
 ParserErrorCode.REPRESENTATION_FIELD_MODIFIER:
   status: needsFix
   notes: Remove it.
+ParserErrorCode.REPRESENTATION_FIELD_TRAILING_COMMA:
+  status: needsFix
+  notes: |-
+    Remove the comma.
 ParserErrorCode.SEALED_ENUM:
   status: needsEvaluation
 ParserErrorCode.SEALED_MIXIN:

pkg/analyzer/lib/src/dart/error/syntactic_errors.g.dart

@@ -1818,6 +1818,13 @@ class ParserErrorCode extends ErrorCode {
     correctionMessage: "Try removing the modifier.",
   );
 
+  static const ParserErrorCode REPRESENTATION_FIELD_TRAILING_COMMA =
+      ParserErrorCode(
+    'REPRESENTATION_FIELD_TRAILING_COMMA',
+    "The representation field can't have a trailing comma.",
+    correctionMessage: "Try removing the trailing comma.",
+  );
+
   static const ParserErrorCode SEALED_ENUM = ParserErrorCode(
     'SEALED_ENUM',
     "Enums can't be declared to be 'sealed'.",

pkg/analyzer/lib/src/error/error_code_values.g.dart

@@ -863,6 +863,7 @@ const List<ErrorCode> errorCodeValues = [
   ParserErrorCode.REDIRECTING_CONSTRUCTOR_WITH_BODY,
   ParserErrorCode.REDIRECTION_IN_NON_FACTORY_CONSTRUCTOR,
   ParserErrorCode.REPRESENTATION_FIELD_MODIFIER,
+  ParserErrorCode.REPRESENTATION_FIELD_TRAILING_COMMA,
   ParserErrorCode.SEALED_ENUM,
   ParserErrorCode.SEALED_MIXIN,
   ParserErrorCode.SEALED_MIXIN_CLASS,

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

@@ -2819,11 +2819,18 @@ class AstBuilder extends StackListener {
       fieldName = firstFormalParameter.name!;
       // Check for multiple fields.
       final maybeComma = firstFormalParameter.endToken.next;
-      if (maybeComma != null && maybeComma != formalParameterList.endToken) {
-        errorReporter.errorReporter?.reportErrorForToken(
-          ParserErrorCode.MULTIPLE_REPRESENTATION_FIELDS,
-          maybeComma,
-        );
+      if (maybeComma != null && maybeComma.type == TokenType.COMMA) {
+        if (formalParameterList.parameters.length == 1) {
+          errorReporter.errorReporter?.reportErrorForToken(
+            ParserErrorCode.REPRESENTATION_FIELD_TRAILING_COMMA,
+            maybeComma,
+          );
+        } else {
+          errorReporter.errorReporter?.reportErrorForToken(
+            ParserErrorCode.MULTIPLE_REPRESENTATION_FIELDS,
+            maybeComma,
+          );
+        }
       }
     } else {
       errorReporter.errorReporter?.reportErrorForToken(

pkg/analyzer/messages.yaml

@@ -20474,6 +20474,9 @@ ParserErrorCode:
   REPRESENTATION_FIELD_MODIFIER:
     problemMessage: "Representation fields can't have modifiers."
     correctionMessage: Try removing the modifier.
+  REPRESENTATION_FIELD_TRAILING_COMMA:
+    problemMessage: The representation field can't have a trailing comma.
+    correctionMessage: Try removing the trailing comma.
   SETTER_IN_FUNCTION:
     problemMessage: "Setters can't be defined within methods or functions."
     correctionMessage: Try moving the setter outside the method or function.

pkg/analyzer/test/src/dart/parser/extension_type_test.dart

@@ -115,6 +115,31 @@ ExtensionTypeDeclaration
 ''');
   }
 
+  test_error_trailingComma() {
+    final parseResult = parseStringWithErrors(r'''
+extension type A(int it,) {}
+''');
+    parseResult.assertErrors([
+      error(ParserErrorCode.REPRESENTATION_FIELD_TRAILING_COMMA, 23, 1),
+    ]);
+
+    final node = parseResult.findNode.singleExtensionTypeDeclaration;
+    assertParsedNodeText(node, r'''
+ExtensionTypeDeclaration
+  extensionKeyword: extension
+  typeKeyword: type
+  name: A
+  representation: RepresentationDeclaration
+    leftParenthesis: (
+    fieldType: NamedType
+      name: int
+    fieldName: it
+    rightParenthesis: )
+  leftBracket: {
+  rightBracket: }
+''');
+  }
+
   test_featureNotEnabled() {
     final parseResult = parseStringWithErrors(r'''
 // @dart = 3.1