[Linter] prefer_padding_over_margin_container lint rule

[ricardodalarme]

Proposal for New Dart Lint Rule

TLDR

Add lint rule to avoid using Container with only a margin property.

Motivation

Using Container with only a margin property introduces an unnecessary widget in the widget tree, as Container adds a range of unused functionalities (decoration, padding, alignment) in this case. Replacing Container with Padding improves performance and makes the widget tree more readable. Padding is also a constant widget, which tends to be more performative.

Alternatives

Instead of creating a new rule, this could be added as an enhancement to the existing avoid_unnecessary_containers rule.

Lint Rule Implementation

• Rule Name: prefer_padding_over_margin_container
• Description: Warns when a Container is used with only a margin property, suggesting the use of Padding instead.
• Severity Level: WARNING (since it is a performance and readability improvement, not a breaking issue)

Code Examples

Bad

Container(
  margin: EdgeInsets.all(8),
  child: Text("Hello, World!"),
);

Good

Padding(
  padding: EdgeInsets.all(8),
  child: Text("Hello, World!"),
);

[dart-github-bot]

Summary: This issue proposes a new Dart lint rule, prefer_padding_over_margin_container, to warn developers when using Container with only a margin property, suggesting the use of Padding instead. This is because Padding is more performant and results in a cleaner widget tree.