[parser] Disallow covariant on extension method parameters

Fixes #38560.

Change-Id: I4c941fb6713983cc01efbe143c7924d0643efe73
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/119332
Commit-Queue: Jens Johansen <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: jensjoha

pkg/analyzer/lib/error/error.dart

@@ -196,6 +196,7 @@ const List<ErrorCode> errorCodeValues = const [
   CompileTimeErrorCode.INVALID_TYPE_ARGUMENT_IN_CONST_SET,
   CompileTimeErrorCode.INVALID_URI,
   CompileTimeErrorCode.INVALID_USE_OF_COVARIANT,
+  // ignore: deprecated_member_use_from_same_package
   CompileTimeErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION,
   CompileTimeErrorCode.INVOCATION_OF_EXTENSION_WITHOUT_CALL,
   CompileTimeErrorCode.LABEL_IN_OUTER_SCOPE,
@@ -522,6 +523,7 @@ const List<ErrorCode> errorCodeValues = const [
   ParserErrorCode.INVALID_STAR_AFTER_ASYNC,
   ParserErrorCode.INVALID_SYNC,
   ParserErrorCode.INVALID_UNICODE_ESCAPE,
+  ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION,
   ParserErrorCode.LIBRARY_DIRECTIVE_NOT_FIRST,
   ParserErrorCode.LOCAL_FUNCTION_DECLARATION_MODIFIER,
   ParserErrorCode.MISSING_ASSIGNABLE_SELECTOR,

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

@@ -481,6 +481,38 @@ class ParserErrorCode extends ErrorCode {
 
   static const ParserErrorCode INVALID_UNICODE_ESCAPE = _INVALID_UNICODE_ESCAPE;
 
+  /**
+   * No parameters.
+   */
+  // #### Description
+  //
+  // The analyzer produces this diagnostic when a member declared inside an
+  // extension uses the keyword `covariant` in the declaration of a parameter.
+  // Extensions aren't classes and don't have subclasses, so the keyword serves
+  // no purpose.
+  //
+  // #### Example
+  //
+  // The following code produces this diagnostic:
+  //
+  // ```dart
+  // extension E on String {
+  //   void a([!covariant!] int i) {}
+  // }
+  // ```
+  //
+  // #### Common fixes
+  //
+  // Remove the 'covariant' keyword:
+  //
+  // ```dart
+  // extension E on String {
+  //   void a(int i) {}
+  // }
+  // ```
+  static const ParserErrorCode INVALID_USE_OF_COVARIANT_IN_EXTENSION =
+      _INVALID_USE_OF_COVARIANT_IN_EXTENSION;
+
   static const ParserErrorCode LIBRARY_DIRECTIVE_NOT_FIRST =
       _LIBRARY_DIRECTIVE_NOT_FIRST;
 

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

@@ -105,6 +105,7 @@ final fastaAnalyzerErrorCodes = <ErrorCode>[
   _MIXIN_DECLARES_CONSTRUCTOR,
   _NULL_AWARE_CASCADE_OUT_OF_ORDER,
   _MULTIPLE_VARIANCE_MODIFIERS,
+  _INVALID_USE_OF_COVARIANT_IN_EXTENSION,
 ];
 
 const ParserErrorCode _ABSTRACT_CLASS_MEMBER = const ParserErrorCode(
@@ -398,6 +399,11 @@ const ParserErrorCode _INVALID_UNICODE_ESCAPE = const ParserErrorCode(
     'INVALID_UNICODE_ESCAPE',
     r"An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.");
 
+const ParserErrorCode _INVALID_USE_OF_COVARIANT_IN_EXTENSION =
+    const ParserErrorCode('INVALID_USE_OF_COVARIANT_IN_EXTENSION',
+        r"Can't have modifier '#lexeme' in an extension.",
+        correction: "Try removing '#lexeme'.");
+
 const ParserErrorCode _LIBRARY_DIRECTIVE_NOT_FIRST = const ParserErrorCode(
     'LIBRARY_DIRECTIVE_NOT_FIRST',
     r"The library directive must appear before all other directives.",

pkg/analyzer/lib/src/error/codes.dart

@@ -2599,40 +2599,9 @@ class CompileTimeErrorCode extends AnalyzerErrorCode {
               "methods or before non-final instance fields.",
           correction: "Try removing the 'covariant' keyword.");
 
-  /**
-   * No parameters.
-   */
-  // #### Description
-  //
-  // The analyzer produces this diagnostic when a member declared inside an
-  // extension uses the keyword `covariant` in the declaration of a parameter.
-  // Extensions aren't classes and don't have subclasses, so the keyword serves
-  // no purpose.
-  //
-  // #### Example
-  //
-  // The following code produces this diagnostic:
-  //
-  // ```dart
-  // extension E on String {
-  //   void a([!covariant!] int i) {}
-  // }
-  // ```
-  //
-  // #### Common fixes
-  //
-  // Remove the 'covariant' keyword:
-  //
-  // ```dart
-  // extension E on String {
-  //   void a(int i) {}
-  // }
-  // ```
-  static const CompileTimeErrorCode INVALID_USE_OF_COVARIANT_IN_EXTENSION =
-      const CompileTimeErrorCode('INVALID_USE_OF_COVARIANT_IN_EXTENSION',
-          "The 'covariant' keyword can't be used in an extension.",
-          correction: "Try removing the 'covariant' keyword.",
-          hasPublishedDocs: true);
+  @Deprecated('Use ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION')
+  static const ParserErrorCode INVALID_USE_OF_COVARIANT_IN_EXTENSION =
+      ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION;
 
   /**
    * 14.2 Exports: It is a compile-time error if the compilation unit found at

pkg/analyzer/lib/src/generated/error_verifier.dart

@@ -5497,10 +5497,7 @@ class ErrorVerifier extends RecursiveAstVisitor<void> {
       Token keyword = parameter.covariantKeyword;
       if (keyword != null) {
         if (_enclosingExtension != null) {
-          _errorReporter.reportErrorForToken(
-            CompileTimeErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION,
-            keyword,
-          );
+          // Reported by the parser.
         } else {
           _errorReporter.reportErrorForToken(
             CompileTimeErrorCode.INVALID_USE_OF_COVARIANT,

pkg/analyzer/test/src/diagnostics/invalid_use_of_covariant_in_extension_test.dart

@@ -3,8 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/analysis/features.dart';
-import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/parser.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/driver_resolution.dart';
@@ -28,7 +28,7 @@ extension E on String {
   void foo({covariant int a}) {}
 }
 ''', [
-      error(CompileTimeErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION, 36, 9),
+      error(ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION, 36, 9),
     ]);
   }
 
@@ -38,7 +38,7 @@ extension E on String {
   void foo([covariant int a]) {}
 }
 ''', [
-      error(CompileTimeErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION, 36, 9),
+      error(ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION, 36, 9),
     ]);
   }
 
@@ -48,7 +48,7 @@ extension E on String {
   void foo(covariant int a) {}
 }
 ''', [
-      error(CompileTimeErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION, 35, 9),
+      error(ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION, 35, 9),
     ]);
   }
 }

pkg/analyzer/tool/diagnostics/diagnostics.md

@@ -1307,7 +1307,7 @@ var x;
 
 ### invalid_use_of_covariant_in_extension
 
-_The 'covariant' keyword can't be used in an extension._
+_Can't have modifier '#lexeme' in an extension._
 
 #### Description
 

pkg/front_end/lib/src/fasta/fasta_codes_generated.dart

@@ -3573,6 +3573,29 @@ Message _withArgumentsExtraneousModifier(Token token) {
       arguments: {'token': token});
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(Token token)>
+    templateExtraneousModifierInExtension =
+    const Template<Message Function(Token token)>(
+        messageTemplate: r"""Can't have modifier '#lexeme' in an extension.""",
+        tipTemplate: r"""Try removing '#lexeme'.""",
+        withArguments: _withArgumentsExtraneousModifierInExtension);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(Token token)> codeExtraneousModifierInExtension =
+    const Code<Message Function(Token token)>(
+        "ExtraneousModifierInExtension", templateExtraneousModifierInExtension,
+        index: 98);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsExtraneousModifierInExtension(Token token) {
+  String lexeme = token.lexeme;
+  return new Message(codeExtraneousModifierInExtension,
+      message: """Can't have modifier '${lexeme}' in an extension.""",
+      tip: """Try removing '${lexeme}'.""",
+      arguments: {'token': token});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeFactoryNotSync = messageFactoryNotSync;
 

pkg/front_end/lib/src/fasta/parser/member_kind.dart

@@ -32,6 +32,12 @@ enum MemberKind {
   /// A top-level method.
   TopLevelMethod,
 
+  /// A non-static method in an extension.
+  ExtensionNonStaticMethod,
+
+  /// A static method in an extension.
+  ExtensionStaticMethod,
+
   /// An instance field in a class.
   NonStaticField,
 

pkg/front_end/lib/src/fasta/parser/modifier_context.dart

@@ -117,6 +117,10 @@ class ModifierRecoveryContext {
         memberKind == MemberKind.TopLevelMethod) {
       reportExtraneousModifier(this.covariantToken);
       this.covariantToken = null;
+    } else if (memberKind == MemberKind.ExtensionNonStaticMethod ||
+        memberKind == MemberKind.ExtensionStaticMethod) {
+      reportExtraneousModifierInExtension(this.covariantToken);
+      this.covariantToken = null;
     }
     if (constToken != null) {
       reportExtraneousModifier(constToken);
@@ -462,6 +466,13 @@ class ModifierRecoveryContext {
     }
   }
 
+  void reportExtraneousModifierInExtension(Token modifier) {
+    if (modifier != null) {
+      parser.reportRecoverableErrorWithToken(
+          modifier, fasta.templateExtraneousModifierInExtension);
+    }
+  }
+
   void reportModifierOutOfOrder(Token modifier, String beforeModifier) {
     parser.reportRecoverableError(
         modifier,

pkg/front_end/lib/src/fasta/parser/parser.dart

@@ -1337,7 +1337,9 @@ class Parser {
       if (isModifier(next)) {
         if (optional('covariant', next)) {
           if (memberKind != MemberKind.StaticMethod &&
-              memberKind != MemberKind.TopLevelMethod) {
+              memberKind != MemberKind.TopLevelMethod &&
+              memberKind != MemberKind.ExtensionNonStaticMethod &&
+              memberKind != MemberKind.ExtensionStaticMethod) {
             covariantToken = token = next;
             next = token.next;
           }
@@ -3327,9 +3329,13 @@ class Parser {
         token,
         name,
         isGetter,
-        staticToken != null
-            ? MemberKind.StaticMethod
-            : MemberKind.NonStaticMethod);
+        kind == DeclarationKind.Extension
+            ? staticToken != null
+                ? MemberKind.ExtensionStaticMethod
+                : MemberKind.ExtensionNonStaticMethod
+            : staticToken != null
+                ? MemberKind.StaticMethod
+                : MemberKind.NonStaticMethod);
     token = parseInitializersOpt(beforeInitializers);
     if (token == beforeInitializers) beforeInitializers = null;
 

pkg/front_end/messages.yaml

@@ -775,6 +775,14 @@ ExtraneousModifier:
     - "abstract typedef foo();"
     - "static typedef foo();"
 
+ExtraneousModifierInExtension:
+  index: 98
+  template: "Can't have modifier '#lexeme' in an extension."
+  tip: "Try removing '#lexeme'."
+  analyzerCode: ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION
+  script:
+    - "extension on String { foo(covariant String child) {} }"
+
 FinalAndCovariant:
   index: 80
   template: "Members can't be declared to be both 'final' and 'covariant'."

pkg/front_end/parser_testcases/extensions/covariant.dart.expect

@@ -47,17 +47,18 @@ beginCompilationUnit(class)
             handleNoType({)
             handleIdentifier(addChild, methodDeclaration)
             handleNoTypeVariables(()
-            beginFormalParameters((, MemberKind.NonStaticMethod)
+            beginFormalParameters((, MemberKind.ExtensionNonStaticMethod)
               beginMetadataStar(covariant)
               endMetadataStar(0)
-              beginFormalParameter(covariant, MemberKind.NonStaticMethod, null, covariant, null)
+              handleRecoverableError(Instance of 'Message', covariant, covariant)
+              beginFormalParameter(covariant, MemberKind.ExtensionNonStaticMethod, null, null, null)
                 handleIdentifier(A, typeReference)
                 handleNoTypeArguments(child)
                 handleType(A, null)
                 handleIdentifier(child, formalParameterDeclaration)
                 handleFormalParameterWithoutValue())
-              endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.NonStaticMethod)
-            endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+              endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.ExtensionNonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.ExtensionNonStaticMethod)
             handleNoInitializers()
             handleAsyncModifier(null, null)
             beginBlockFunctionBody({)

pkg/front_end/parser_testcases/extensions/covariant.dart.intertwined.expect

@@ -89,23 +89,25 @@ parseUnit(class)
               parseQualifiedRestOpt(addChild, methodDeclarationContinuation)
               parseMethodTypeVar(addChild)
                 listener: handleNoTypeVariables(()
-              parseGetterOrFormalParameters(addChild, addChild, false, MemberKind.NonStaticMethod)
-                parseFormalParameters(addChild, MemberKind.NonStaticMethod)
-                  parseFormalParametersRest((, MemberKind.NonStaticMethod)
-                    listener: beginFormalParameters((, MemberKind.NonStaticMethod)
-                    parseFormalParameter((, FormalParameterKind.mandatory, MemberKind.NonStaticMethod)
+              parseGetterOrFormalParameters(addChild, addChild, false, MemberKind.ExtensionNonStaticMethod)
+                parseFormalParameters(addChild, MemberKind.ExtensionNonStaticMethod)
+                  parseFormalParametersRest((, MemberKind.ExtensionNonStaticMethod)
+                    listener: beginFormalParameters((, MemberKind.ExtensionNonStaticMethod)
+                    parseFormalParameter((, FormalParameterKind.mandatory, MemberKind.ExtensionNonStaticMethod)
                       parseMetadataStar(()
                         listener: beginMetadataStar(covariant)
                         listener: endMetadataStar(0)
-                      listener: beginFormalParameter(covariant, MemberKind.NonStaticMethod, null, covariant, null)
+                      reportRecoverableErrorWithToken(covariant, Instance of 'Template<(Token) => Message>')
+                        listener: handleRecoverableError(Instance of 'Message', covariant, covariant)
+                      listener: beginFormalParameter(covariant, MemberKind.ExtensionNonStaticMethod, null, null, null)
                       listener: handleIdentifier(A, typeReference)
                       listener: handleNoTypeArguments(child)
                       listener: handleType(A, null)
                       ensureIdentifier(A, formalParameterDeclaration)
                         listener: handleIdentifier(child, formalParameterDeclaration)
                       listener: handleFormalParameterWithoutValue())
-                      listener: endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.NonStaticMethod)
-                    listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+                      listener: endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.ExtensionNonStaticMethod)
+                    listener: endFormalParameters(1, (, ), MemberKind.ExtensionNonStaticMethod)
               parseInitializersOpt())
                 listener: handleNoInitializers()
               parseAsyncModifierOpt())

pkg/front_end/parser_testcases/extensions/not_covariant.dart.expect

@@ -47,17 +47,17 @@ beginCompilationUnit(class)
             handleNoType({)
             handleIdentifier(addChild, methodDeclaration)
             handleNoTypeVariables(()
-            beginFormalParameters((, MemberKind.NonStaticMethod)
+            beginFormalParameters((, MemberKind.ExtensionNonStaticMethod)
               beginMetadataStar(A)
               endMetadataStar(0)
-              beginFormalParameter(A, MemberKind.NonStaticMethod, null, null, null)
+              beginFormalParameter(A, MemberKind.ExtensionNonStaticMethod, null, null, null)
                 handleIdentifier(A, typeReference)
                 handleNoTypeArguments(child)
                 handleType(A, null)
                 handleIdentifier(child, formalParameterDeclaration)
                 handleFormalParameterWithoutValue())
-              endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.NonStaticMethod)
-            endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+              endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.ExtensionNonStaticMethod)
+            endFormalParameters(1, (, ), MemberKind.ExtensionNonStaticMethod)
             handleNoInitializers()
             handleAsyncModifier(null, null)
             beginBlockFunctionBody({)

pkg/front_end/parser_testcases/extensions/not_covariant.dart.intertwined.expect

@@ -89,23 +89,23 @@ parseUnit(class)
               parseQualifiedRestOpt(addChild, methodDeclarationContinuation)
               parseMethodTypeVar(addChild)
                 listener: handleNoTypeVariables(()
-              parseGetterOrFormalParameters(addChild, addChild, false, MemberKind.NonStaticMethod)
-                parseFormalParameters(addChild, MemberKind.NonStaticMethod)
-                  parseFormalParametersRest((, MemberKind.NonStaticMethod)
-                    listener: beginFormalParameters((, MemberKind.NonStaticMethod)
-                    parseFormalParameter((, FormalParameterKind.mandatory, MemberKind.NonStaticMethod)
+              parseGetterOrFormalParameters(addChild, addChild, false, MemberKind.ExtensionNonStaticMethod)
+                parseFormalParameters(addChild, MemberKind.ExtensionNonStaticMethod)
+                  parseFormalParametersRest((, MemberKind.ExtensionNonStaticMethod)
+                    listener: beginFormalParameters((, MemberKind.ExtensionNonStaticMethod)
+                    parseFormalParameter((, FormalParameterKind.mandatory, MemberKind.ExtensionNonStaticMethod)
                       parseMetadataStar(()
                         listener: beginMetadataStar(A)
                         listener: endMetadataStar(0)
-                      listener: beginFormalParameter(A, MemberKind.NonStaticMethod, null, null, null)
+                      listener: beginFormalParameter(A, MemberKind.ExtensionNonStaticMethod, null, null, null)
                       listener: handleIdentifier(A, typeReference)
                       listener: handleNoTypeArguments(child)
                       listener: handleType(A, null)
                       ensureIdentifier(A, formalParameterDeclaration)
                         listener: handleIdentifier(child, formalParameterDeclaration)
                       listener: handleFormalParameterWithoutValue())
-                      listener: endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.NonStaticMethod)
-                    listener: endFormalParameters(1, (, ), MemberKind.NonStaticMethod)
+                      listener: endFormalParameter(null, null, child, null, null, FormalParameterKind.mandatory, MemberKind.ExtensionNonStaticMethod)
+                    listener: endFormalParameters(1, (, ), MemberKind.ExtensionNonStaticMethod)
               parseInitializersOpt())
                 listener: handleNoInitializers()
               parseAsyncModifierOpt())