avoid-bottom-type-in-patterns

added in: 1.5.0

warning

Dart 3.0+

Warns when a pattern contains a void, Never or Null type.

Presence of these types inside a pattern is most likely a bug.

Example

❌ Bad:

final object = WithField('hello');

if (object case Null()) {} // LINT
if (object case Never()) {} // LINT
if (object case final Null value) {} // LINT
if (object case final Never value) {} // LINT

if (object case Never() || Null()) {} // LINT
if (object case Never() || WithField()) {} // LINT

final value = switch (object) {
  Null() => 'bad', // LINT
  Never() => 'bad', // LINT
};

✅ Good:

final object = WithField('hello');

if (object == null) {}
if (object case == null) {}

if (object case WithField()) {}

final value = switch (object) {
  == null => 'good',
  _ => 'good',
};