unnecessary-nesting

Flag an if whose entire body is a second if—the two could be a single if with the conditions joined by &&, dropping a needless level of nesting. It fires only when neither if has an else (an else on either side changes what runs) and the inner if is the sole statement of the outer one.

The fix joins the conditions with &&, parenthesizing each non-primary condition so the grouping is preserved. It is unsafe (collapsing dedents the body, so a reformat may follow) and withheld when it would drop a comment.

This rule is enabled by default.

An if whose only body is another if can be a single if:

if (a) {
  if (b) {
    do_thing()
  }
}

warning: unnecessary-nesting
 --> example.R:2:3
  |
2 |   if (b) {
  |   ^^ this `if` is nested in another `if` with no `else`
  = help: Combine the two conditions with `&&` to drop a level of nesting.