`manual_try_fold`: check that `fold` is really `Iterator::fold` Fix #11876 changelog: [`manual_try_fold`]: suggest using `try_fold` only for `Iterator::fold` uses
`manual_try_fold`: check that `fold` is really `Iterator::fold` Fix #11876 changelog: [`manual_try_fold`]: suggest using `try_fold` only for `Iterator::fold` uses