use_closest_build_context

v0.4.0 Warning Fix Widget Best Practices

This rule catches cases where an outer BuildContext is used inside a nested builder callback (Builder, LayoutBuilder, etc.) that provides its own context. This commonly happens when the inner parameter is renamed to _ because it was previously unused, and then the outer context is accidentally referenced.

Why use this rule

Using the wrong BuildContext can cause lookups like Theme.of(context) or Navigator.of(context) to find the wrong ancestor widget. For example, inside a Builder the outer context does not reflect widgets introduced by the Builder itself. This leads to subtle bugs where your theme, navigator, or scaffold operations target the wrong part of the widget tree.

See also: BuildContext

Don’t

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Builder(
      builder: (_) {
        // Uses the outer context instead of the Builder's own context
        return _buildChild(context);
      },
    );
  }
}

Do

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Builder(
      builder: (context) {
        // Uses the Builder's own context
        return _buildChild(context);
      },
    );
  }
}

Configuration

This rule is in the recommended preset, so it is on with preset: recommended or preset: opinionated. Add it to preset: core with use_closest_build_context: true.

To turn it off:

many_lints.yaml

rules:
  use_closest_build_context: false

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

Related rules

• never_discard_build_context — Don’t discard a BuildContext parameter with a wildcard.
• avoid_build_context_in_providers — Providers outlive widgets, so they should not receive a BuildContext.
• avoid_passing_build_context_to_blocs — Prevent passing BuildContext to Bloc or Cubit classes.
• avoid_too_many_widgets_per_build — Keep one build method within a widget budget.