collapsible-else-if

Flags an else whose entire body is a single if, which can be written as else if.

Rationale

else { if (…) { … } } is the same control flow as else if (…) { … } with an extra level of braces and indentation. The else if form is shorter and is how the chain is normally written.

What triggers

The rule fires when an else branch is a block containing exactly one statement, and that statement is an if. The nested if may keep its own else chain — it is preserved as-is:

if (a) {
} else {
    if (b) {
    } else {
    }
}

becomes

if (a) {
} else if (b) {
} else {
}

What does not trigger

• A comment in the else block around the nested if. Collapsing would discard it, so the rule backs off.
• An else block with more than the single nested if.
• An else if already written as such — there is no wrapping block to remove.