Prevent bugs caused by elements with zero counts in the set. - #1
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Since the map should never store elements with a count of 0, it is better to store the count as `NonZero<usize>` instead of `usize`. This also allows the `Iter` impl to become smaller and simpler. More importantly, before this change, it was possible to insert an element into the set with a count of zero using `insert_times(val, 0)`, which would've produced misbehavior such as `contains(&val)` returning `true`. The use of `NonZero` makes this bug pop out and less likely to be reintroduced in the future. Now `insert_times(val, 0)` is correctly treated as a no-op. Another source of an element with a count of zero was doing `insert_times(val, usize::MAX); insert_times(val, 1);` with overflow checks disabled, as they are by default in release mode. Now `insert_times()` checks for overflow of the inserted element count as well as the size of the whole set. There is a user-visible change in the signature of `distinct_elements` in that it now surfaces `NonZero<usize>` instead of `usize`. Other API are unchanged. This change also fixes a couple of clippy lints about elided `'_` lifetimes, and missing `edition` key in the crate manifest.
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Since the map should never store elements with a count of 0, it is better to store the count as
NonZero<usize>instead ofusize. This also allows theIterimpl to become smaller and simpler.More importantly, before this change, it was possible to insert an element into the set with a count of zero using
insert_times(val, 0), which would've produced misbehavior such ascontains(&val)returningtrue. The use ofNonZeromakes this bug pop out and less likely to be reintroduced in the future. Nowinsert_times(val, 0)is correctly treated as a no-op.Another source of an element with a count of zero was doing
insert_times(val, usize::MAX); insert_times(val, 1);with overflow checks disabled, as they are by default in release mode. Nowinsert_times()checks for overflow of the inserted element count as well as the size of the whole set.There is a user-visible change in the signature of
distinct_elementsin that it now surfacesNonZero<usize>instead ofusize. Other API are unchanged.This change also fixes a couple of clippy lints about elided
'_lifetimes, and missingeditionkey in the crate manifest.Also sent to multiset