[quick fix] new correction for unnecessary_underscores

Bug: #56595
Change-Id: If7faeca31b4340fcd4b7d5f4642caf284cf36308
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403383
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: pq

pkg/analysis_server/lib/src/services/correction/dart/convert_to_wildcard_variable.dart

@@ -30,6 +30,12 @@ class ConvertToWildcardVariable extends ResolvedCorrectionProducer {
     if (!wildcardVariablesEnabled) return;
 
     var node = this.node;
+
+    if (node is FormalParameter) {
+      await computeFormalParameterConversion(builder, node);
+      return;
+    }
+
     if (node is! VariableDeclaration) return;
 
     var nameToken = node.name;
@@ -55,4 +61,13 @@ class ConvertToWildcardVariable extends ResolvedCorrectionProducer {
       }
     });
   }
+
+  Future<void> computeFormalParameterConversion(
+    ChangeBuilder builder,
+    FormalParameter node,
+  ) async {
+    await builder.addDartFileEdit(file, (builder) {
+      builder.addSimpleReplacement(range.token(node.name!), '_');
+    });
+  }
 }

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

@@ -2456,7 +2456,7 @@ LintCode.unnecessary_this:
 LintCode.unnecessary_to_list_in_spreads:
   status: hasFix
 LintCode.unnecessary_underscores:
-  status: needsFix  
+  status: hasFix  
 LintCode.unreachable_from_main:
   status: hasFix
 LintCode.unrelated_type_equality_checks_in_expression:

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

@@ -511,6 +511,7 @@ final _builtInLintProducers = <LintCode, List<ProducerGenerator>>{
   ],
   LinterLintCode.unnecessary_to_list_in_spreads: [RemoveToList.new],
   LinterLintCode.unnecessary_this: [RemoveThisExpression.new],
+  LinterLintCode.unnecessary_underscores: [ConvertToWildcardVariable.new],
   LinterLintCode.unreachable_from_main: [RemoveUnusedElement.new],
   LinterLintCode.use_colored_box: [ReplaceContainerWithColoredBox.new],
   LinterLintCode.use_decorated_box: [ReplaceWithDecoratedBox.new],

pkg/analysis_server/test/src/services/correction/fix/convert_to_wildcard_variable_test.dart

@@ -4,13 +4,15 @@
 
 import 'package:analysis_server/src/services/correction/fix.dart';
 import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
+import 'package:linter/src/lint_names.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'fix_processor.dart';
 
 void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToWildcardVariableTest);
+    defineReflectiveTests(ConvertUnnecessaryUnderscoresTest);
   });
 }
 
@@ -116,3 +118,36 @@ void f() {
     await assertNoFix();
   }
 }
+
+@reflectiveTest
+class ConvertUnnecessaryUnderscoresTest extends FixProcessorLintTest {
+  @override
+  FixKind get kind => DartFixKind.CONVERT_TO_WILDCARD_VARIABLE;
+
+  @override
+  String get lintCode => LintNames.unnecessary_underscores;
+
+  Future<void> test_functionParameter() async {
+    await resolveTestCode(r'''
+void f(int __) {}
+''');
+    await assertHasFix(r'''
+void f(int _) {}
+''');
+  }
+
+  Future<void> test_localVariable() async {
+    await resolveTestCode(r'''
+void f() {
+  // ignore: UNUSED_LOCAL_VARIABLE
+  int __ = 0;
+}
+''');
+    await assertHasFix(r'''
+void f() {
+  // ignore: UNUSED_LOCAL_VARIABLE
+  int _ = 0;
+}
+''');
+  }
+}