prefer_const_border_radius

v0.4.0 Warning Fix Widget Replacement

Flags usages of BorderRadius.circular() which should be replaced with BorderRadius.all(Radius.circular(...)). The BorderRadius.circular() factory delegates to BorderRadius.all(Radius.circular()) internally, but it cannot be made const because it is a factory constructor.

Why use this rule

BorderRadius.circular() calls BorderRadius.all(Radius.circular()) under the hood. Using the explicit form allows the entire expression to be const, which means the Dart compiler can canonicalize it at compile time. This avoids repeated allocations in build methods and is especially beneficial for border radii that never change.

See also: BorderRadius | Dart lint: prefer_const_constructors

Don’t

// BorderRadius.circular cannot be const
final radius = BorderRadius.circular(8);

final radius2 = BorderRadius.circular(16.0);

Do

// BorderRadius.all(Radius.circular()) supports const
final radius = BorderRadius.all(Radius.circular(8));

const radius2 = BorderRadius.all(Radius.circular(16.0));

Configuration

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

many_lints.yaml

rules:
  prefer_const_border_radius: true

To turn it off again:

many_lints.yaml

rules:
  prefer_const_border_radius: false

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

Related rules

• avoid_border_all — Use Border.fromBorderSide instead of Border.all for const support.
• avoid_expanded_as_spacer — Use Spacer instead of Expanded with an empty child.
• avoid_incorrect_image_opacity — Use Image’s opacity parameter instead of wrapping in Opacity.
• avoid_wrapping_in_padding — Avoid wrapping widgets that support padding in a Padding widget.