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| 1 // Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file | |
| 2 // for details. All rights reserved. Use of this source code is governed by a | |
| 3 // BSD-style license that can be found in the LICENSE file. | |
| 4 | |
| 5 library linter.src.rules.dont_compare_unrelated_types_for_equality; | |
| 6 | |
| 7 import 'package:analyzer/dart/ast/ast.dart'; | |
| 8 import 'package:analyzer/dart/ast/token.dart'; | |
| 9 import 'package:analyzer/dart/ast/visitor.dart'; | |
| 10 import 'package:analyzer/dart/element/element.dart'; | |
| 11 import 'package:analyzer/dart/element/type.dart'; | |
| 12 import 'package:linter/src/linter.dart'; | |
| 13 | |
| 14 const String _desc = r'Equality operator (==) invocation with references of' | |
| 15 r' unrelated types.'; | |
| 16 | |
| 17 const String _details = r''' | |
| 18 | |
| 19 **DON'T** Compare references of unrelated types for equality. | |
| 20 Comparing references of a type where neither is a subtype of the other most | |
| 21 likely will return false and might not reflect programmer's intent. | |
| 22 | |
| 23 **BAD:** | |
| 24 ``` | |
| 25 void someFunction() { | |
| 26 var x = '1'; | |
| 27 if (x == 1) print('someFunction'); // LINT | |
| 28 } | |
| 29 ``` | |
| 30 | |
| 31 **BAD:** | |
| 32 ``` | |
| 33 void someFunction1() { | |
| 34 String x = '1'; | |
| 35 if (x == 1) print('someFunction1'); // LINT | |
| 36 } | |
| 37 ``` | |
| 38 | |
| 39 **BAD:** | |
| 40 ``` | |
| 41 void someFunction13(DerivedClass2 instance) { | |
| 42 var other = new DerivedClass3(); | |
| 43 | |
| 44 if (other == instance) print('someFunction13'); // LINT | |
| 45 } | |
| 46 | |
| 47 class ClassBase {} | |
| 48 | |
| 49 class DerivedClass1 extends ClassBase {} | |
| 50 | |
| 51 abstract class Mixin {} | |
| 52 | |
| 53 class DerivedClass2 extends ClassBase with Mixin {} | |
| 54 | |
| 55 class DerivedClass3 extends ClassBase implements Mixin {} | |
| 56 ``` | |
| 57 | |
| 58 **GOOD:** | |
| 59 ``` | |
| 60 void someFunction2() { | |
| 61 var x = '1'; | |
| 62 var y = '2'; | |
| 63 if (x == y) print(someFunction2); // OK | |
| 64 } | |
| 65 ``` | |
| 66 | |
| 67 **GOOD:** | |
| 68 ``` | |
| 69 void someFunction3() { | |
| 70 for (var i = 0; i < 10; i++) { | |
| 71 if (i == 0) print(someFunction3); // OK | |
| 72 } | |
| 73 } | |
| 74 ``` | |
| 75 | |
| 76 **GOOD:** | |
| 77 ``` | |
| 78 void someFunction4() { | |
| 79 var x = '1'; | |
| 80 if (x == null) print(someFunction4); // OK | |
| 81 } | |
| 82 ``` | |
| 83 | |
| 84 **GOOD:** | |
| 85 ``` | |
| 86 void someFunction7() { | |
| 87 List someList; | |
| 88 | |
| 89 if (someList.length == 0) print('someFunction7'); // OK | |
| 90 } | |
| 91 ``` | |
| 92 | |
| 93 **GOOD:** | |
| 94 ``` | |
| 95 void someFunction8(ClassBase instance) { | |
| 96 DerivedClass1 other; | |
| 97 | |
| 98 if (other == instance) print('someFunction8'); // OK | |
| 99 } | |
| 100 ``` | |
| 101 | |
| 102 **GOOD:** | |
| 103 ``` | |
| 104 void someFunction10(unknown) { | |
| 105 var what = unknown - 1; | |
| 106 for (var index = 0; index < unknown; index++) { | |
| 107 if (what == index) print('someFunction10'); // OK | |
| 108 } | |
| 109 } | |
| 110 ``` | |
| 111 | |
| 112 **GOOD:** | |
| 113 ``` | |
| 114 void someFunction11(Mixin instance) { | |
| 115 var other = new DerivedClass2(); | |
| 116 | |
| 117 if (other == instance) print('someFunction11'); // OK | |
| 118 if (other != instance) print('!someFunction11'); // OK | |
| 119 } | |
| 120 | |
| 121 class ClassBase {} | |
| 122 | |
| 123 abstract class Mixin {} | |
| 124 | |
| 125 class DerivedClass2 extends ClassBase with Mixin {} | |
| 126 ``` | |
| 127 '''; | |
| 128 | |
| 129 class DontCompareUnrelatedTypesForEquality extends LintRule { | |
| 130 _Visitor _visitor; | |
| 131 | |
| 132 DontCompareUnrelatedTypesForEquality() : super( | |
| 133 name: 'dont_compare_unrelated_types_for_equality', | |
| 134 description: _desc, | |
| 135 details: _details, | |
| 136 group: Group.errors, | |
| 137 maturity: Maturity.experimental) { | |
| 138 _visitor = new _Visitor(this); | |
| 139 } | |
| 140 | |
| 141 @override | |
| 142 AstVisitor getVisitor() => _visitor; | |
| 143 } | |
| 144 | |
| 145 class _Visitor extends SimpleAstVisitor { | |
| 146 static const String _dartCoreLibraryName = 'dart.core'; | |
| 147 static const String _boolClassName = 'bool'; | |
| 148 | |
| 149 final LintRule rule; | |
| 150 | |
| 151 _Visitor(this.rule); | |
| 152 | |
| 153 @override | |
| 154 void visitBinaryExpression(BinaryExpression node) { | |
| 155 bool isDartCoreBoolean = node.bestType.name == _boolClassName && | |
| 156 node.bestType.element?.library?.name == _dartCoreLibraryName; | |
| 157 if (!isDartCoreBoolean || (node.operator.type != TokenType.EQ_EQ && | |
| 158 node.operator.type != TokenType.BANG_EQ)) { | |
| 159 return; | |
| 160 } | |
| 161 | |
| 162 if (_unrelatedTypes(node)) { | |
| 163 rule.reportLint(node); | |
| 164 } | |
| 165 } | |
| 166 | |
| 167 bool _unrelatedTypes(BinaryExpression node) { | |
| 168 DartType leftType = node.leftOperand.bestType; | |
| 169 DartType rightType = node.rightOperand.bestType; | |
| 170 if (leftType.isBottom || leftType.isDynamic || rightType.isBottom || rightTy
pe.isDynamic) { | |
| 171 return false; | |
| 172 } | |
| 173 if (leftType == rightType || | |
| 174 leftType.isMoreSpecificThan(rightType) || | |
| 175 rightType.isMoreSpecificThan(leftType)) { | |
| 176 return false; | |
| 177 } | |
| 178 Element leftElement = leftType.element; | |
| 179 Element rightElement = rightType.element; | |
| 180 if (leftElement is ClassElement && rightElement is ClassElement) { | |
| 181 return leftElement.supertype.isObject || | |
| 182 leftElement.supertype != rightElement.supertype; | |
| 183 } | |
| 184 return false; | |
| 185 } | |
| 186 } | |
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Chromium Code Reviews
Issue 1972183002:
Linter version 0.1.16 bump [TBR]. (Closed)
Base URL: https://github.com/dart-lang/linter.git@master