collapsible-if

Flags an if whose entire body is a single nested if, where the two can be merged into one by &&-combining their conditions.

Rationale

Each if adds a level of nesting. When the inner if is the only thing the outer one does, that nesting is noise — the guard is really a single compound condition, and reads more clearly written as one.

What triggers

The rule fires when all of the following hold:

1. The outer if has no else.
2. Its body is exactly one statement, and that statement is an if.
3. The inner if has no else.

Either else would change which condition guards the fall-through, so the merge would not preserve behaviour — those cases are left alone.

What does not trigger

• A comment in the outer block around the nested if. Collapsing would discard it, so the rule backs off.
• An outer block with more than the single nested if.

Example

if (ready) {
    if (count > 0) {
        process();
    }
}

Fixed:

if (ready && count > 0) {
    process();
}

A condition that binds looser than && (an || / or, a ternary) is wrapped in parentheses when merged, so if (a || b) { if (c) { … } } becomes if ((a || b) && c) { … }.