[analyzer] Hardcode IgnoreValidator.enableUnignorableIgnore flag.

This flag existed to allow the `unignorable_ignore` diagnostic to be
easily disabled in case it caused problems in Flutter. This CL removes
the flag, hardcoding the behavior that the diagnostic is enabled.

Change-Id: I6a6a696462e893244917f17ff694ddd2c862a880
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/463641
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

Author: stereotype441

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

@@ -9,7 +9,6 @@ import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/src/diagnostic/diagnostic.dart' as diag;
 import 'package:analyzer/src/ignore_comments/ignore_info.dart';
 import 'package:analyzer/src/lint/registry.dart';
-import 'package:meta/meta.dart';
 
 /// Used to validate the ignore comments in a single file.
 class IgnoreValidator {
@@ -28,20 +27,6 @@ class IgnoreValidator {
   static late DiagnosticCode unnecessaryIgnoreNameLocationLintCode;
   static late DiagnosticCode unnecessaryIgnoreNameFileLintCode;
 
-  /// Whether to report `unignorable_ignore` warnings.
-  ///
-  /// `unignorable_ignore` warnings were introduced in
-  /// https://dart-review.googlesource.com/c/sdk/+/156402 but not enabled until
-  /// https://dart-review.googlesource.com/c/sdk/+/463504.
-  ///
-  /// This flag allows the logic for reporting these warnings to be easily
-  /// disabled again in case this leads to problems, without interfering with
-  /// the ability to unit test the functionality.
-  // TODO(paulberry): remove this flag once sufficient time has elapsed after
-  // rolling https://dart-review.googlesource.com/c/sdk/+/463504 into Flutter.
-  @visibleForTesting
-  static bool enableUnignorableIgnore = true;
-
   /// The diagnostic reporter to which diagnostics are to be reported.
   final DiagnosticReporter _diagnosticReporter;
 
@@ -169,18 +154,16 @@ class IgnoreValidator {
     List<IgnoredElement> duplicated,
     List<IgnoredElement> list,
   ) {
-    if (enableUnignorableIgnore) {
-      for (var unignorableName in unignorable) {
-        if (unignorableName is IgnoredDiagnosticName) {
-          var name = unignorableName.name;
-          _diagnosticReporter.atOffset(
-            diagnosticCode: diag.unignorableIgnore,
-            offset: unignorableName.offset,
-            length: name.length,
-            arguments: [name],
-          );
-          list.remove(unignorableName);
-        }
+    for (var unignorableName in unignorable) {
+      if (unignorableName is IgnoredDiagnosticName) {
+        var name = unignorableName.name;
+        _diagnosticReporter.atOffset(
+          diagnosticCode: diag.unignorableIgnore,
+          offset: unignorableName.offset,
+          length: name.length,
+          arguments: [name],
+        );
+        list.remove(unignorableName);
       }
     }
     for (var ignoredElement in duplicated) {

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

@@ -9,10 +9,8 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/diagnostic/diagnostic.dart' as diag;
-import 'package:analyzer/src/error/ignore_validator.dart';
 import 'package:analyzer/src/test_utilities/lint_registration_mixin.dart';
 import 'package:analyzer_testing/utilities/utilities.dart';
-import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
@@ -26,16 +24,6 @@ main() {
 @reflectiveTest
 class UnignorableIgnoreTest extends PubPackageResolutionTest
     with LintRegistrationMixin {
-  @override
-  void setUp() {
-    var enableUnignorableIgnore = IgnoreValidator.enableUnignorableIgnore;
-    addTearDown(() {
-      IgnoreValidator.enableUnignorableIgnore = enableUnignorableIgnore;
-    });
-    IgnoreValidator.enableUnignorableIgnore = true;
-    super.setUp();
-  }
-
   @override
   Future<void> tearDown() {
     unregisterLintRules();