avoid_empty_spread

v0.8.0 Warning Fix Collection Type

This rule flags a spread element whose operand is an empty collection literal — ...[], ...{}, ...<int>[].

Why use this rule

Spreading an empty literal contributes nothing to the surrounding collection. It is dead syntax, usually left behind after a refactor removed the elements, or written as a placeholder that was never filled in.

Beyond the noise, it misleads: a reader scanning a widget’s children sees a spread and assumes something conditional is happening there.

Don’t

Column(
  children: [
    const Header(),
    // Contributes nothing
    ...[],
    const Footer(),
  ],
)

Do

Column(
  children: [
    const Header(),
    const Footer(),
  ],
)

If the spread was a placeholder for conditional content, make the condition explicit:

Column(
  children: [
    const Header(),
    if (showDetails) const Details(),
    const Footer(),
  ],
)

Known limitations

Only literal empty collections are reported. A spread of a variable that happens to be empty at runtime (...items) is never flagged, since emptiness is not knowable at analysis time. Null-aware spreads of a variable (...?items) are likewise left alone.

Configuration

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

To turn it off:

many_lints.yaml

rules:
  avoid_empty_spread: false

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

Related rules

• avoid_accessing_collections_by_constant_index — Avoid accessing a collection by a constant index inside a loop.
• avoid_collection_equality_checks — Avoid comparing collections with == or != as it checks reference equality, not contents.
• avoid_collection_methods_with_unrelated_types — Avoid calling collection methods with arguments whose types are unrelated to the collection’s type parameter.
• avoid_duplicate_collection_elements — Don’t repeat the same element in a collection literal.