no_equal_then_else

v1.0.0 Warning Control Flow

This rule flags an if/else or conditional expression whose branches are identical. If both branches do the same thing, the condition decides nothing.

It means one of two things: a branch was meant to differ and does not — the usual case, and a real bug — or the branching is dead weight that should collapse. The shape appears through copy-paste, and nothing about it is a type error, so it survives review easily.

See also: Dart: branches

Don’t

void showDashboard() {}

void render({required bool isAdmin}) {
  if (isAdmin) {
    showDashboard();
  } else {
    showDashboard();
  }
}

A conditional expression is checked the same way:

String label({required bool isActive}) => isActive ? 'on' : 'on';

Do

Make the branches differ:

void showDashboard() {}
void showHome() {}

void render({required bool isAdmin}) {
  if (isAdmin) {
    showDashboard();
  } else {
    showHome();
  }
}

Or drop the condition, if it really decided nothing:

void showDashboard() {}

void render() {
  showDashboard();
}

Known limitations

Branches are compared by source text, with a single-statement block reduced to that statement so { f(); } and f(); compare equal. Two branches that compute the same result by different code are not reported — that is beyond what a lint can judge.

An else if chain is skipped: comparing the first branch against a whole nested if says nothing useful. Two empty branches are skipped too, since that is usually code mid-way through being written.

Known limitations

Branches are compared by source text, with a single-statement block reduced to that statement so { f(); } and f(); compare equal. Two branches that compute the same result by different code are not reported — that is beyond what a lint can judge.

An else if chain is skipped: comparing the first branch against a whole nested if says nothing useful. Two empty branches are skipped too, since that is usually code mid-way through being written.

Configuration

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

To turn it off:

many_lints.yaml

rules:
  no_equal_then_else: false

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

Related rules

• no_equal_conditions — Flag an if/else-if chain that repeats a condition.
• no_equal_switch_case — Flag two switch branches with identical bodies.
• avoid_redundant_else — Drop the else when the if branch always exits.
• avoid_cascade_after_if_null — Detect cascades after if-null operators without parentheses.