New Lint quick-fix: unnecessary_this (#29469)

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

@@ -112,7 +112,8 @@ bool hasFix(ErrorCode errorCode) =>
             errorCode.name == LintNames.avoid_init_to_null ||
             errorCode.name == LintNames.prefer_collection_literals ||
             errorCode.name == LintNames.unnecessary_brace_in_string_interp ||
-            errorCode.name == LintNames.unnecessary_lambdas));
+            errorCode.name == LintNames.unnecessary_lambdas ||
+            errorCode.name == LintNames.unnecessary_this));
 
 /**
  * An enumeration of possible quick fix kinds.
@@ -208,6 +209,8 @@ class DartFixKind {
       'REMOVE_PARENTHESIS_IN_GETTER_INVOCATION',
       50,
       "Remove parentheses in getter invocation");
+  static const REMOVE_THIS_EXPRESSION =
+      const FixKind('REMOVE_THIS_EXPRESSION', 50, "Remove this expression");
   static const REMOVE_UNNECESSARY_CAST =
       const FixKind('REMOVE_UNNECESSARY_CAST', 50, "Remove unnecessary cast");
   static const REMOVE_UNUSED_CATCH_CLAUSE =

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

@@ -22,7 +22,6 @@ import 'package:analysis_server/src/services/correction/namespace.dart';
 import 'package:analysis_server/src/services/correction/source_buffer.dart';
 import 'package:analysis_server/src/services/correction/source_range.dart'
     as rf;
-import 'package:analysis_server/src/services/correction/source_range.dart';
 import 'package:analysis_server/src/services/correction/strings.dart';
 import 'package:analysis_server/src/services/correction/util.dart';
 import 'package:analysis_server/src/services/search/hierarchy.dart';
@@ -394,6 +393,9 @@ class FixProcessor {
       if (errorCode.name == LintNames.unnecessary_lambdas) {
         _addFix_replaceWithTearOff();
       }
+      if (errorCode.name == LintNames.unnecessary_this) {
+        _addFix_removeThisExpression();
+      }
     }
     // done
     return fixes;
@@ -686,8 +688,8 @@ class FixProcessor {
           _addInsertEdit,
           _addRemoveEdit,
           _addReplaceEdit,
-          rangeStartLength,
-          rangeNode);
+          rf.rangeStartLength,
+          rf.rangeNode);
       _addFix(DartFixKind.CONVERT_FLUTTER_CHILD, []);
       return;
     }
@@ -1844,6 +1846,20 @@ class FixProcessor {
     }
   }
 
+  void _addFix_removeThisExpression() {
+    final thisExpression = node is ThisExpression
+        ? node
+        : node.getAncestor((node) => node is ThisExpression);
+    final parent = thisExpression.parent;
+    if (parent is PropertyAccess) {
+      _addRemoveEdit(rf.rangeStartEnd(parent.offset, parent.operator.end));
+      _addFix(DartFixKind.REMOVE_THIS_EXPRESSION, []);
+    } else if (parent is MethodInvocation) {
+      _addRemoveEdit(rf.rangeStartEnd(parent.offset, parent.operator.end));
+      _addFix(DartFixKind.REMOVE_THIS_EXPRESSION, []);
+    }
+  }
+
   void _addFix_removeUnnecessaryCast() {
     if (coveredNode is! AsExpression) {
       return;
@@ -3111,6 +3127,7 @@ class LintNames {
   static const String unnecessary_brace_in_string_interp =
       'unnecessary_brace_in_string_interp';
   static const String unnecessary_lambdas = 'unnecessary_lambdas';
+  static const String unnecessary_this = 'unnecessary_this';
 }
 
 /**

pkg/analysis_server/test/services/correction/fix_test.dart

@@ -5986,6 +5986,94 @@ var x;
 ''');
   }
 
+  test_removeThisExpression_methodInvocation_oneCharacterOperator() async {
+    String src = '''
+class A {
+  void foo() {
+    /*LINT*/this.foo();
+  }
+}
+''';
+    await findLint(src, LintNames.unnecessary_this);
+
+    await applyFix(DartFixKind.REMOVE_THIS_EXPRESSION);
+
+    verifyResult('''
+class A {
+  void foo() {
+    foo();
+  }
+}
+''');
+  }
+
+  test_removeThisExpression_methodInvocation_twoCharactersOperator() async {
+    String src = '''
+class A {
+  void foo() {
+    /*LINT*/this?.foo();
+  }
+}
+''';
+    await findLint(src, LintNames.unnecessary_this);
+
+    await applyFix(DartFixKind.REMOVE_THIS_EXPRESSION);
+
+    verifyResult('''
+class A {
+  void foo() {
+    foo();
+  }
+}
+''');
+  }
+
+  test_removeThisExpression_propertyAccess_oneCharacterOperator() async {
+    String src = '''
+class A {
+  int x;
+  void foo() {
+    /*LINT*/this.x = 2;
+  }
+}
+''';
+    await findLint(src, LintNames.unnecessary_this);
+
+    await applyFix(DartFixKind.REMOVE_THIS_EXPRESSION);
+
+    verifyResult('''
+class A {
+  int x;
+  void foo() {
+    x = 2;
+  }
+}
+''');
+  }
+
+  test_removeThisExpression_propertyAccess_twoCharactersOperator() async {
+    String src = '''
+class A {
+  int x;
+  void foo() {
+    /*LINT*/this?.x = 2;
+  }
+}
+''';
+    await findLint(src, LintNames.unnecessary_this);
+
+    await applyFix(DartFixKind.REMOVE_THIS_EXPRESSION);
+
+    verifyResult('''
+class A {
+  int x;
+  void foo() {
+    x = 2;
+  }
+}
+''');
+  }
+
   test_replaceWithLiteral_linkedHashMap_withCommentsInGeneric() async {
     String src = '''
 import 'dart:collection';