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avoid-unnecessary-length-check

v1.30.0
warning
effort: 2m
teams+

Warns when the if statement's condition has a collection length check that can be removed.

If the if statement has only an inner for-loop, it won't be executed when there are no elements in the collection. In such cases the condition can be removed.

Example​

❌ Bad:

void fn(List<int> arr) {
  // LINT: This length check is unnecessary because the inner loop will not be executed when there are no elements.
  //  Consider removing this length check.
  if (arr.isNotEmpty) {
    for (final item in arr) {
      // ...
    }
  }

  // LINT: This length check is unnecessary because the inner loop will not be executed when there are no elements.
  //  Consider removing this length check.
  if (arr.length != 0) {
    arr.forEach((_) {
      // ...
    });
  }
}

✅ Good:

void fn(List<int> arr) {
  for (final item in arr) {
    // ...
  }

  if (arr.isNotEmpty) {
    arr.forEach((_) {
      // ...
    });

    // some other code
  }
}
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