[cfe] Report error on immediately declared abstract membrs in enums

Part of #47453

Change-Id: I376b309e019a1e18444613f14c9e8870c0f10eb6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/239681
Reviewed-by: Johnni Winther <[email protected]>
Commit-Queue: Chloe Stefantsova <[email protected]>

Author: chloestefantsova

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -2781,6 +2781,14 @@ const Code<Null> codeEncoding = messageEncoding;
 const MessageCode messageEncoding = const MessageCode("Encoding",
     problemMessage: r"""Unable to decode bytes as UTF-8.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeEnumAbstractMember = messageEnumAbstractMember;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageEnumAbstractMember = const MessageCode(
+    "EnumAbstractMember",
+    problemMessage: r"""Enums can't declare abstract members.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
     Message Function(

pkg/front_end/lib/src/fasta/kernel/hierarchy/members_node.dart

@@ -27,6 +27,7 @@ import '../../messages.dart'
         messageDeclaredMemberConflictsWithInheritedMember,
         messageDeclaredMemberConflictsWithInheritedMemberCause,
         messageDeclaredMemberConflictsWithOverriddenMembersCause,
+        messageEnumAbstractMember,
         messageInheritedMembersConflict,
         messageInheritedMembersConflictCause1,
         messageInheritedMembersConflictCause2,
@@ -2351,14 +2352,19 @@ class ClassMembersNodeBuilder {
     Map<String, LocatedMessage> contextMap = <String, LocatedMessage>{};
     for (ClassMember declaration in unfoldDeclarations(abstractMembers)) {
       if (isNameVisibleIn(declaration.name, classBuilder.libraryBuilder)) {
-        String name = declaration.fullNameForErrors;
-        String className = declaration.classBuilder.fullNameForErrors;
-        String displayName =
-            declaration.isSetter ? "$className.$name=" : "$className.$name";
-        contextMap[displayName] = templateMissingImplementationCause
-            .withArguments(displayName)
-            .withLocation(
-                declaration.fileUri, declaration.charOffset, name.length);
+        if (classBuilder.isEnum && declaration.classBuilder == classBuilder) {
+          classBuilder.addProblem(messageEnumAbstractMember,
+              declaration.charOffset, declaration.name.text.length);
+        } else {
+          String name = declaration.fullNameForErrors;
+          String className = declaration.classBuilder.fullNameForErrors;
+          String displayName =
+              declaration.isSetter ? "$className.$name=" : "$className.$name";
+          contextMap[displayName] = templateMissingImplementationCause
+              .withArguments(displayName)
+              .withLocation(
+                  declaration.fileUri, declaration.charOffset, name.length);
+        }
       }
     }
     if (contextMap.isEmpty) return;

pkg/front_end/messages.status

@@ -214,6 +214,8 @@ DuplicatedName/example: Fail
 DuplicatedNamedArgument/example: Fail
 DuplicatedParameterName/example: Fail
 Encoding/analyzerCode: Fail
+EnumAbstractMember/analyzerCode: Fail
+EnumAbstractMember/example: Fail
 EnumConstantSameNameAsEnclosing/example: Fail
 EnumConstructorSuperInitializer/analyzerCode: Fail
 EnumConstructorSuperInitializer/example: Fail

pkg/front_end/messages.yaml

@@ -5577,3 +5577,6 @@ EnumContainsRestrictedInstanceDeclaration:
 
 EnumImplementerContainsRestrictedInstanceDeclaration:
   problemMessage: "'#name' has 'Enum' as a superinterface and can't contain non-static members with name '#name2'."
+
+EnumAbstractMember:
+  problemMessage: "Enums can't declare abstract members."

pkg/front_end/testcases/enhanced_enums/abstract_members.dart

@@ -0,0 +1,57 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+enum E1 {
+  element;
+
+  void foo(); // Error.
+}
+
+enum E2 {
+  element;
+
+  int get foo; // Error.
+}
+
+enum E3 {
+  element;
+
+  void set foo(int val); // Error.
+}
+
+abstract class InterfaceMethod {
+  void foo();
+}
+
+enum E4 implements InterfaceMethod { // Error.
+  element
+}
+
+abstract class InterfaceGetter {
+  int get foo;
+}
+
+enum E5 implements InterfaceGetter { // Error.
+  element
+}
+
+abstract class InterfaceSetter {
+  void set foo(int val);
+}
+
+enum E6 implements InterfaceSetter { // Error.
+  element
+}
+
+mixin MethodImplementation {
+  void foo() {}
+}
+
+enum E7 with MethodImplementation {
+  element;
+
+  void foo(); // Ok.
+}
+
+main() {}

pkg/front_end/testcases/enhanced_enums/abstract_members.dart.strong.expect

@@ -0,0 +1,190 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:8:8: Error: Enums can't declare abstract members.
+//   void foo(); // Error.
+//        ^^^
+//
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:14:11: Error: Enums can't declare abstract members.
+//   int get foo; // Error.
+//           ^^^
+//
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:20:12: Error: Enums can't declare abstract members.
+//   void set foo(int val); // Error.
+//            ^^^
+//
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:27:6: Error: The non-abstract class 'E4' is missing implementations for these members:
+//  - InterfaceMethod.foo
+// Try to either
+//  - provide an implementation,
+//  - inherit an implementation from a superclass or mixin,
+//  - mark the class as abstract, or
+//  - provide a 'noSuchMethod' implementation.
+//
+// enum E4 implements InterfaceMethod { // Error.
+//      ^^
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:24:8: Context: 'InterfaceMethod.foo' is defined here.
+//   void foo();
+//        ^^^
+//
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:35:6: Error: The non-abstract class 'E5' is missing implementations for these members:
+//  - InterfaceGetter.foo
+// Try to either
+//  - provide an implementation,
+//  - inherit an implementation from a superclass or mixin,
+//  - mark the class as abstract, or
+//  - provide a 'noSuchMethod' implementation.
+//
+// enum E5 implements InterfaceGetter { // Error.
+//      ^^
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:32:11: Context: 'InterfaceGetter.foo' is defined here.
+//   int get foo;
+//           ^^^
+//
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:43:6: Error: The non-abstract class 'E6' is missing implementations for these members:
+//  - InterfaceSetter.foo=
+// Try to either
+//  - provide an implementation,
+//  - inherit an implementation from a superclass or mixin,
+//  - mark the class as abstract, or
+//  - provide a 'noSuchMethod' implementation.
+//
+// enum E6 implements InterfaceSetter { // Error.
+//      ^^
+// pkg/front_end/testcases/enhanced_enums/abstract_members.dart:40:12: Context: 'InterfaceSetter.foo=' is defined here.
+//   void set foo(int val);
+//            ^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class E1 extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E1> values = #C4;
+  static const field self::E1 element = #C3;
+  const constructor •(core::int index, core::String name) → self::E1
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E1.${this.{core::_Enum::_name}{core::String}}";
+  abstract method foo() → void;
+}
+class E2 extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E2> values = #C6;
+  static const field self::E2 element = #C5;
+  const constructor •(core::int index, core::String name) → self::E2
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E2.${this.{core::_Enum::_name}{core::String}}";
+  abstract get foo() → core::int;
+}
+class E3 extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E3> values = #C8;
+  static const field self::E3 element = #C7;
+  const constructor •(core::int index, core::String name) → self::E3
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E3.${this.{core::_Enum::_name}{core::String}}";
+  abstract set foo(core::int val) → void;
+}
+abstract class InterfaceMethod extends core::Object {
+  synthetic constructor •() → self::InterfaceMethod
+    : super core::Object::•()
+    ;
+  abstract method foo() → void;
+}
+class E4 extends core::_Enum implements self::InterfaceMethod /*isEnum*/  {
+  static const field core::List<self::E4> values = #C10;
+  static const field self::E4 element = #C9;
+  const constructor •(core::int index, core::String name) → self::E4
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E4.${this.{core::_Enum::_name}{core::String}}";
+}
+abstract class InterfaceGetter extends core::Object {
+  synthetic constructor •() → self::InterfaceGetter
+    : super core::Object::•()
+    ;
+  abstract get foo() → core::int;
+}
+class E5 extends core::_Enum implements self::InterfaceGetter /*isEnum*/  {
+  static const field core::List<self::E5> values = #C12;
+  static const field self::E5 element = #C11;
+  const constructor •(core::int index, core::String name) → self::E5
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E5.${this.{core::_Enum::_name}{core::String}}";
+}
+abstract class InterfaceSetter extends core::Object {
+  synthetic constructor •() → self::InterfaceSetter
+    : super core::Object::•()
+    ;
+  abstract set foo(core::int val) → void;
+}
+class E6 extends core::_Enum implements self::InterfaceSetter /*isEnum*/  {
+  static const field core::List<self::E6> values = #C14;
+  static const field self::E6 element = #C13;
+  const constructor •(core::int index, core::String name) → self::E6
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E6.${this.{core::_Enum::_name}{core::String}}";
+}
+abstract class MethodImplementation extends core::Object /*isMixinDeclaration*/  {
+  method foo() → void {}
+}
+abstract class _E7&_Enum&MethodImplementation = core::_Enum with self::MethodImplementation /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •(core::int index, core::String _name) → self::_E7&_Enum&MethodImplementation
+    : super core::_Enum::•(index, _name)
+    ;
+  mixin-super-stub method foo() → void
+    return super.{self::MethodImplementation::foo}();
+}
+class E7 extends self::_E7&_Enum&MethodImplementation /*isEnum*/  {
+  static const field core::List<self::E7> values = #C16;
+  static const field self::E7 element = #C15;
+  const constructor •(core::int index, core::String name) → self::E7
+    : super self::_E7&_Enum&MethodImplementation::•(index, name)
+    ;
+  method toString() → core::String
+    return "E7.${this.{core::_Enum::_name}{core::String}}";
+  abstract method foo() → void;
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = 0
+  #C2 = "element"
+  #C3 = self::E1 {index:#C1, _name:#C2}
+  #C4 = <self::E1>[#C3]
+  #C5 = self::E2 {index:#C1, _name:#C2}
+  #C6 = <self::E2>[#C5]
+  #C7 = self::E3 {index:#C1, _name:#C2}
+  #C8 = <self::E3>[#C7]
+  #C9 = self::E4 {index:#C1, _name:#C2}
+  #C10 = <self::E4>[#C9]
+  #C11 = self::E5 {index:#C1, _name:#C2}
+  #C12 = <self::E5>[#C11]
+  #C13 = self::E6 {index:#C1, _name:#C2}
+  #C14 = <self::E6>[#C13]
+  #C15 = self::E7 {index:#C1, _name:#C2}
+  #C16 = <self::E7>[#C15]
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///abstract_members.dart:
+- E1. (from org-dartlang-testcase:///abstract_members.dart:5:6)
+- _Enum. (from org-dartlang-sdk:///sdk/lib/core/enum.dart:103:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- E2. (from org-dartlang-testcase:///abstract_members.dart:11:6)
+- E3. (from org-dartlang-testcase:///abstract_members.dart:17:6)
+- E4. (from org-dartlang-testcase:///abstract_members.dart:27:6)
+- E5. (from org-dartlang-testcase:///abstract_members.dart:35:6)
+- E6. (from org-dartlang-testcase:///abstract_members.dart:43:6)
+- E7. (from org-dartlang-testcase:///abstract_members.dart:51:6)
+- _E7&_Enum&MethodImplementation. (from org-dartlang-testcase:///abstract_members.dart:51:6)