flutter_semantic_lints

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Not style. Not formatting.

This package detects meaningless Flutter code.

---

Why this exists

Most lint packages focus on:

• style
• naming
• best practices

But they miss something critical:

Code that works but makes no sense.

This package detects:

• conflicting parameters
• useless parameters
• no-effect widgets

---

Rules

box_decoration_color_gradient

Bad:

BoxDecoration(
  color: Colors.red,
  gradient: LinearGradient(...),
)

color is ignored.

Good:

BoxDecoration(
  color: Colors.red,
)

Good:

BoxDecoration(
  gradient: LinearGradient(...),
)

Use either color or gradient, not both.

container_color_decoration

Bad:

Container(
  color: Colors.red,
  decoration: BoxDecoration(...),
)

color conflicts with decoration.

Good:

Container(
  color: Colors.red,
)

Good:

Container(
  decoration: BoxDecoration(
    color: Colors.red,
  ),
)

Move the color into decoration when using decoration.

expanded_flex_one

Bad:

Expanded(flex: 1)

Default value is already 1.

Good:

Expanded(
  child: child,
)

Good:

Expanded(
  flex: 2,
  child: child,
)

Omit flex when the value is 1.

visibility_visible_true

Bad:

Visibility(
  visible: true,
  child: child,
)

The child is already visible.

Good:

child

Good:

Visibility(
  visible: isVisible,
  child: child,
)

Use Visibility when visibility is dynamic.

edge_insets_all_zero

Bad:

EdgeInsets.all(0)

EdgeInsets.zero already represents zero insets.

Good:

EdgeInsets.zero

border_radius_circular_zero

Bad:

BorderRadius.circular(0)

BorderRadius.zero already represents no radius.

Good:

BorderRadius.zero

opacity_one

Bad:

Opacity(
  opacity: 1.0,
  child: ...,
)

No visual effect. Adds cost only.

Good:

child

Good:

Opacity(
  opacity: 0.5,
  child: child,
)

Remove Opacity when the value is 1.0.

padding_zero

Bad:

Padding(
  padding: EdgeInsets.zero,
  child: child,
)

No spacing is added.

Good:

child

transform_scale_one

Bad:

Transform.scale(
  scale: 1.0,
  child: child,
)

The child is not scaled.

Good:

child

rotated_box_zero_turns

Bad:

RotatedBox(
  quarterTurns: 0,
  child: child,
)

The child is not rotated.

Good:

child

Installation

dev_dependencies:
  custom_lint:
  flutter_semantic_lints:

Setup

analyzer:
  plugins:
    - custom_lint

Run

dart run custom_lint

Configuration

All rules are enabled by default.

Disable a rule:

analyzer:
  plugins:
    - custom_lint

custom_lint:
  rules:
    - opacity_one: false

Enable only selected rules:

analyzer:
  plugins:
    - custom_lint

custom_lint:
  enable_all_lint_rules: false
  rules:
    - box_decoration_color_gradient
    - container_color_decoration

Philosophy

• correctness over style
• semantics over formatting
• signal over noise

Rule Categories

conflicting_parameter

• box_decoration_color_gradient
• container_color_decoration

useless_parameter

• expanded_flex_one
• visibility_visible_true
• edge_insets_all_zero
• border_radius_circular_zero

no_effect_widget

• opacity_one
• padding_zero
• transform_scale_one
• rotated_box_zero_turns

Testing

The example project doubles as integration coverage.

cp example/analysis_options.custom_lint.yaml example/analysis_options.yaml
cd example
dart run custom_lint

Positive cases use // expect_lint: comments. Negative and edge cases live in separate example files and should stay quiet.

Non-goals

• style lint
• naming rules
• formatting
• architecture opinions

Status

MVP

Implemented rules:

• BoxDecoration conflict
• Container conflict
• Expanded(flex: 1)
• Opacity(1.0)
• Visibility(visible: true)
• EdgeInsets.all(0)
• BorderRadius.circular(0)
• Padding(padding: EdgeInsets.zero)
• Transform.scale(scale: 1.0)
• RotatedBox(quarterTurns: 0)

Contributing

Only submit rules that:

• are objectively correct
• have near-zero false positives
• are explainable in one sentence

License

MIT