avoid_empty_setstate

v0.8.0WarningConfigurableState Management

This rule flags setState(() {}) — a call whose callback contains no statements.

Why use this rule

An empty callback means the state was already mutated somewhere else and setState is being used purely as a “please rebuild” signal. It works, but it separates the mutation from the rebuild request, which causes three problems:

• Readers cannot see what changed by looking at the setState call.
• The framework’s debug assertions, which run around the callback, no longer bracket the actual mutation.
• If the mutation later moves after the setState call, the rebuild silently renders stale values.

Putting the mutation inside the callback fixes all three and costs nothing.

See also: State.setState docs

Don’t

void increment() {
  _counter++;
  // The rebuild request is detached from the change
  setState(() {});
}

Do

void increment() {
  setState(() {
    _counter++;
  });
}

Known limitations

Only a genuinely empty block is reported. A callback containing any statement is left alone, even if that statement has no effect — proving a statement is a no-op is outside this rule’s scope.

Turning this rule off

This rule is in the opinionated preset, so it is on with preset: opinionated, or by name:

many_lints.yaml

rules:
  avoid_empty_setstate: true

To turn it off again:

many_lints.yaml

rules:
  avoid_empty_setstate: false

To keep the rule on but skip certain paths, use per-rule exclude.

Options

Projects with a state abstraction that does not extend Flutter’s State can opt that base class into this rule:

analysis_options.yaml

analysis_options.yaml

many_lints:
  rules:
    avoid_empty_setstate:
      state_base_classes: [AppState]

many_lints.yaml

many_lints.yaml

rules:
  avoid_empty_setstate:
    state_base_classes: [AppState]

Option	Type	Default	Description
state_base_classes	list of strings	[]	Additional non-State base classes whose subclasses should be treated as state classes

Related rules

• avoid_mounted_in_setstate — Detect mounted checks inside setState callbacks.
• avoid_unnecessary_setstate — Detect unnecessary setState calls in lifecycle methods.
• avoid_inherited_widget_in_initstate — Don’t look up inherited widgets inside initState.
• avoid_late_context — Don’t read BuildContext in a late field initializer.