flutter_semantic_lints 0.1.0

Custom lint rules that detect meaningless, conflicting, or no-effect Flutter code.

flutter_semantic_lints

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.

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.

Installation

dev_dependencies:
  custom_lint:
  flutter_semantic_lints:

Setup

analyzer:
  plugins:
    - custom_lint

Run

dart run custom_lint

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

no_effect_widget

• opacity_one

Testing

The example project doubles as integration coverage.

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)

Contributing

Only submit rules that:

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

License

MIT