### Bug fixes

* [#313](https://github.com/rubocop/rubocop-performance/issues/313): Fix a false negative for `Performance/RedundantStringChars` when using `str.chars.last` without argument. ([@koic][])
* [#321](https://github.com/rubocop/rubocop-performance/pull/321): Fix a false positive for `Performance/Sum` when using `TargetRubyVersion` is 2.3 or lower. ([@koic][])
* [#314](https://github.com/rubocop/rubocop-performance/issues/314): Fix `Performance/RegexpMatch` to handle `::Regexp`. ([@fatkodima][])

### Changes

* [#318](https://github.com/rubocop/rubocop-performance/issues/318): Extend `Performance/StringInclude` to handle `!~`. ([@fatkodima][])

[@koic]: https://github.com/koic
[@fatkodima]: https://github.com/fatkodima
