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avoid-negations-in-equality-checks

v1.24.0
warning
has auto-fix
pro+

Warns when an equality check has a negated expression.

Negated boolean expressions reduce readability and can sometimes be a mistake (e.g. == !value instead of != value).

Example​

❌ Bad:

void fn(bool flag, bool another) {
  // LINT: Avoid negated expressions in equality checks.
  //  Try removing this negation and inverting the operator.
  if (!flag == another) {}

  // LINT: Avoid negated expressions in equality checks.
  //  Try removing this negation and inverting the operator.
  if (!flag != another) {}

  // LINT: Avoid negated expressions in equality checks.
  //  Try removing this negation and inverting the operator.
  if (flag == !another) {}

  // LINT: Avoid negated expressions in equality checks.
  //  Try removing this negation and inverting the operator.
  if (flag != !another) {}
}

✅ Good:

void fn(bool flag, bool another) {
  if (flag != another) {}

  if (flag == another) {}

  if (flag != another) {}

  if (flag == another) {}
}
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