function_always_returns_same_value

v1.0.0 Warning Code Quality

This rule flags a function where every return yields the same constant, so the branching around them decides nothing.

Why use this rule

Whatever the caller passes, the answer is fixed. Either a branch was meant to return something else and does not — the usual case, and a silent one — or the function should be a constant and its parameters dropped.

Only literal constants are compared, and only when there are at least two returns; one return of a constant is an ordinary function. A return; with no value, or a return inside a nested closure, means the rule cannot prove one fixed answer and stays quiet.

Protocol callbacks are never reported

Some callbacks are supposed to return the same value on every path, because the value is a signal to a framework rather than an answer. onNotification must return false throughout to let a notification keep bubbling; the method exists for its side effect.

Two checks cover them: a set of known names (onNotification, shouldRepaint, …) plus any on... method, and — because a protocol callback can be given a descriptive name — the shape, where any parameter typed ...Notification marks the method as a listener.

Don’t

int scoreFor(Player player) {
  if (player.isWinner) return 3;
  return 3; // the branch changes nothing
}

Do

int scoreFor(Player player) {
  if (player.isWinner) return 3;
  return 0;
}

Turning this rule off

This rule is in the recommended preset, so it is on with preset: recommended or preset: opinionated.

To disable this rule:

many_lints.yaml

rules:
  function_always_returns_same_value: false

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

Related rules

• function_always_returns_null — A nullable-returning function whose every path returns null.
• avoid_accessing_other_classes_private_members — Make the underscore mean what everyone reads it as.
• avoid_commented_out_code — Detect and flag commented-out code.
• avoid_complex_conditions — Keep boolean conditions within an operand budget.