It has helped me occasionally. Quite occasionally.
It also only looks at locals, so something like
fn foo() {}
fn bar() {
let baz = 0;
fo()
}
is not as helpful as it could be…
<anon>:5:5: 5:7 error: unresolved name `fo`. Did you mean `baz`?
I think I’m in favour of turning it off (OTOH, having it popping up uselessly might get someone to improve it in a fit of rage
).