collapsible-if

Flags an if that only contains another if, where the two conditions can be joined with &&.

Why

When the inner if is all the outer one does, the nesting doesn’t add anything. The two checks are really one condition and read better written as one.

What it flags

An if without an else whose only statement is another if without an else. With an else on either of them, merging would change what runs, so those are left alone.

A condition that binds looser than &&, like an || or a ternary, gets parentheses when merged: if (a || b) { if (c) { … } } becomes if ((a || b) && c) { … }.

What it leaves alone

• An if with a comment next to the inner if, since merging would lose the comment.
• An if with anything besides the inner if.

Example

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

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