avoid-always-null-variables

v1.39.0

warning

effort: 2m

pro+

Warns when a variable is always null in the current code branch.

Example

❌ Bad:

void fn(String? value, String another) {
  if (value == null) {
    // LINT: This variable is always null in the current code branch.
    //  Try replacing it with a different variable or a null literal.
    print(value);
  }

  if (value == null) {
    // LINT: This variable is always null in the current code branch.
    //  Try replacing it with a different variable or a null literal.
    print(value ?? another);
  }

  if (value != null) {
    ...
  } else {
    // LINT: This variable is always null in the current code branch.
    //  Try replacing it with a different variable or a null literal.
    print(value);
  }
}

✅ Good:

void fn(String? value, String another) {
  if (value == null) {
    print(null);
  }

  if (value == null) {
    print(another);
  }

  if (value != null) {
    ...
  }
}

Related Rules

• function-always-returns-null
• avoid-always-null-parameters