readability-else-after-return

LLVM Coding Standards advises to reduce indentation where possible and where it makes understanding code easier. Early exit is one of the suggested enforcements of that. Please do not use else or else if after something that interrupts control flow - like return, break, continue, throw.

The following piece of code illustrates how the check works. This piece of code:

void foo(int Value) {
  int Local = 0;
  for (int i = 0; i < 42; i++) {
    if (Value == 1) {
      return;
    } else {
      Local++;
    }

    if (Value == 2)
      continue;
    else
      Local++;

    if (Value == 3) {
      throw 42;
    } else {
      Local++;
    }
  }
}

Would be transformed into:

void foo(int Value) {
  int Local = 0;
  for (int i = 0; i < 42; i++) {
    if (Value == 1) {
      return;
    }
    Local++;

    if (Value == 2)
      continue;
    Local++;

    if (Value == 3) {
      throw 42;
    }
    Local++;
  }
}

Options

WarnOnUnfixable

When true, emit a warning for cases where the check can’t output a Fix-It. These can occur with declarations inside the else branch that would have an extended lifetime if the else branch was removed. Default value is true.

WarnOnConditionVariables

When true, the check will attempt to refactor a variable defined inside the condition of the if statement that is used in the else branch defining them just before the if statement. This can only be done if the if statement is the last statement in its parent’s scope. Default value is true.

LLVM alias

There is an alias of this check called llvm-else-after-return. In that version the options WarnOnUnfixable and WarnOnConditionVariables are both set to false by default.

This check helps to enforce this LLVM Coding Standards recommendation.