unrelated_type_equality_checks
Equality operator ==
invocation with references of unrelated types.
This rule is available as of Dart 2.0.
Rule sets: core, recommended, flutter
Details
#DON'T Compare references of unrelated types for equality.
Comparing references of a type where neither is a subtype of the other most likely will return false
and might not reflect programmer's intent.
Int64
and Int32
from package:fixnum
allow comparing to int
provided the int
is on the right hand side. The lint allows this as a special case.
BAD:
void someFunction() {
var x = '1';
if (x == 1) print('someFunction'); // LINT
}
BAD:
void someFunction1() {
String x = '1';
if (x == 1) print('someFunction1'); // LINT
}
BAD:
void someFunction13(DerivedClass2 instance) {
var other = DerivedClass3();
if (other == instance) print('someFunction13'); // LINT
}
class ClassBase {}
class DerivedClass1 extends ClassBase {}
abstract class Mixin {}
class DerivedClass2 extends ClassBase with Mixin {}
class DerivedClass3 extends ClassBase implements Mixin {}
GOOD:
void someFunction2() {
var x = '1';
var y = '2';
if (x == y) print(someFunction2); // OK
}
GOOD:
void someFunction3() {
for (var i = 0; i < 10; i++) {
if (i == 0) print(someFunction3); // OK
}
}
GOOD:
void someFunction4() {
var x = '1';
if (x == null) print(someFunction4); // OK
}
GOOD:
void someFunction7() {
List someList;
if (someList.length == 0) print('someFunction7'); // OK
}
GOOD:
void someFunction8(ClassBase instance) {
DerivedClass1 other;
if (other == instance) print('someFunction8'); // OK
}
GOOD:
void someFunction10(unknown) {
var what = unknown - 1;
for (var index = 0; index < unknown; index++) {
if (what == index) print('someFunction10'); // OK
}
}
GOOD:
void someFunction11(Mixin instance) {
var other = DerivedClass2();
if (other == instance) print('someFunction11'); // OK
if (other != instance) print('!someFunction11'); // OK
}
class ClassBase {}
abstract class Mixin {}
class DerivedClass2 extends ClassBase with Mixin {}
Usage
#To enable the unrelated_type_equality_checks
rule, add unrelated_type_equality_checks
under linter > rules in your analysis_options.yaml
file:
linter:
rules:
- unrelated_type_equality_checks
Unless stated otherwise, the documentation on this site reflects Dart 3.5.3. Page last updated on 2024-07-03. View source or report an issue.