### New features

* `Rails/TimeZone` emits acceptable methods on a violation when `EnforcedStyle` is `:acceptable`. ([@l8nite][])
* Recognize rackup file (config.ru) out of the box. ([@carhartl][])
* [#1788](https://github.com/rubocop/rubocop/pull/1788): New cop `ModuleLength` checks for overly long module definitions. ([@sdeframond][])
* New cop `Performance/Count` to convert `Enumerable#select...size`, `Enumerable#reject...size`, `Enumerable#select...count`, `Enumerable#reject...count` `Enumerable#select...length`, and `Enumerable#reject...length` to `Enumerable#count`. ([@rrosenblum][])
* `CommentAnnotation` cop does auto-correction. ([@dylandavidson][])
* New cop `Style/TrailingUnderscoreVariable` to remove trailing underscore variables from mass assignment. ([@rrosenblum][])
* [#1136](https://github.com/rubocop/rubocop/issues/1136): New cop `Performance/ParallelAssignment` to avoid usages of unnecessary parallel assignment. ([@rrosenblum][])
* [#1278](https://github.com/rubocop/rubocop/issues/1278): `DefEndAlignment` and `EndAlignment` cops do auto-correction. ([@lumeet][])
* `IndentationWidth` cop follows the `AlignWith` option of the `DefEndAlignment` cop. ([@lumeet][])
* [#1837](https://github.com/rubocop/rubocop/issues/1837): New cop `EachWithObjectArgument` checks that `each_with_object` isn't called with an immutable object as argument. ([@jonas054][])
* `ArrayJoin` cop does auto-correction. ([@tmr08c][])

### Bugs fixed

* [#1816](https://github.com/rubocop/rubocop/issues/1816): Fix bug in `Sample` when calling `#shuffle` with something other than an element selector. ([@rrosenblum][])
* [#1768](https://github.com/rubocop/rubocop/pull/1768): `DefEndAlignment` recognizes preceding `private_class_method` or `public_class_method` before `def`. ([@til][])
* [#1820](https://github.com/rubocop/rubocop/issues/1820): Correct the logic in `AlignHash` for when to ignore a key because it's not on its own line. ([@jonas054][])
* [#1829](https://github.com/rubocop/rubocop/pull/1829): Fix bug in `Sample` and `FlatMap` that would cause them to report having been auto-corrected when they were not. ([@rrosenblum][])
* [#1832](https://github.com/rubocop/rubocop/pull/1832): Fix bug in `UnusedMethodArgument` that would cause them to report having been auto-corrected when they were not. ([@jonas054][])
* [#1834](https://github.com/rubocop/rubocop/issues/1834): Support only boolean values for `AutoCorrect` configuration parameter, and remove warning for unknown parameter. ([@jonas054][])
* [#1843](https://github.com/rubocop/rubocop/issues/1843): Fix crash in `TrailingBlankLines` when a file ends with a block comment without final newline. ([@jonas054][])
* [#1849](https://github.com/rubocop/rubocop/issues/1849): Fix bug where you cannot have nested arrays in the Rake task configuration. ([@rrosenblum][])
* Fix bug in `MultilineTernaryOperator` where it will not register an offense when only the false branch is on a separate line. ([@rrosenblum][])
* Fix crash in `MultilineBlockLayout` when using new lambda literal syntax without parentheses. ([@hbd225][])
* [#1859](https://github.com/rubocop/rubocop/pull/1859): Fix bugs in `IfUnlessModifier` concerning comments and empty lines. ([@jonas054][])
* Fix handling of trailing comma in `SpaceAroundBlockParameters` and `SpaceAfterComma`. ([@lumeet][])

[@bbatsov]: https://github.com/bbatsov
[@jonas054]: https://github.com/jonas054
[@yujinakayama]: https://github.com/yujinakayama
[@dblock]: https://github.com/dblock
[@nevir]: https://github.com/nevir
[@daviddavis]: https://github.com/daviddavis
[@sds]: https://github.com/sds
[@fancyremarker]: https://github.com/fancyremarker
[@sinisterchipmunk]: https://github.com/sinisterchipmunk
[@vonTronje]: https://github.com/vonTronje
[@agrimm]: https://github.com/agrimm
[@pmenglund]: https://github.com/pmenglund
[@chulkilee]: https://github.com/chulkilee
[@codez]: https://github.com/codez
[@emou]: https://github.com/emou
[@skanev]: http://github.com/skanev
[@claco]: http://github.com/claco
[@rifraf]: http://github.com/rifraf
[@scottmatthewman]: https://github.com/scottmatthewman
[@ma2gedev]: http://github.com/ma2gedev
[@jeremyolliver]: https://github.com/jeremyolliver
[@hannestyden]: https://github.com/hannestyden
[@geniou]: https://github.com/geniou
[@jkogara]: https://github.com/jkogara
[@tmorris-fiksu]: https://github.com/tmorris-fiksu
[@mockdeep]: https://github.com/mockdeep
[@hiroponz]: https://github.com/hiroponz
[@tamird]: https://github.com/tamird
[@fshowalter]: https://github.com/fshowalter
[@cschramm]: https://github.com/cschramm
[@bquorning]: https://github.com/bquorning
[@bcobb]: https://github.com/bcobb
[@irrationalfab]: https://github.com/irrationalfab
[@tommeier]: https://github.com/tommeier
[@sfeldon]: https://github.com/sfeldon
[@biinari]: https://github.com/biinari
[@barunio]: https://github.com/barunio
[@molawson]: https://github.com/molawson
[@wndhydrnt]: https://github.com/wndhydrnt
[@ggilder]: https://github.com/ggilder
[@salbertson]: https://github.com/salbertson
[@camilleldn]: https://github.com/camilleldn
[@mcls]: https://github.com/mcls
[@yous]: https://github.com/yous
[@vrthra]: https://github.com/vrthra
[@SkuliOskarsson]: https://github.com/SkuliOskarsson
[@jspanjers]: https://github.com/jspanjers
[@sch1zo]: https://github.com/sch1zo
[@smangelsdorf]: https://github.com/smangelsdorf
[@mvz]: https://github.com/mvz
[@jfelchner]: https://github.com/jfelchner
[@janraasch]: https://github.com/janraasch
[@jcarbo]: https://github.com/jcarbo
[@oneamtu]: https://github.com/oneamtu
[@toy]: https://github.com/toy
[@Koronen]: https://github.com/Koronen
[@blainesch]: https://github.com/blainesch
[@marxarelli]: https://github.com/marxarelli
[@katieschilling]: https://github.com/katieschilling
[@kakutani]: https://github.com/kakutani
[@rrosenblum]: https://github.com/rrosenblum
[@mattjmcnaughton]: https://github.com/mattjmcnaughton
[@huerlisi]: https://github.com/huerlisi
[@volkert]: https://github.com/volkert
[@lumeet]: https://github.com/lumeet
[@mmozuras]: https://github.com/mmozuras
[@d4rk5eed]: https://github.com/d4rk5eed
[@cshaffer]: https://github.com/cshaffer
[@eitoball]: https://github.com/eitoball
[@iainbeeston]: https://github.com/iainbeeston
[@pimterry]: https://github.com/pimterry
[@palkan]: https://github.com/palkan
[@jdoconnor]: https://github.com/jdoconnor
[@meganemura]: https://github.com/meganemura
[@zvkemp]: https://github.com/zvkemp
[@vassilevsky]: https://github.com/vassilevsky
[@gerry3]: https://github.com/gerry3
[@ypresto]: https://github.com/ypresto
[@clowder]: https://github.com/clowder
[@mudge]: https://github.com/mudge
[@mzp]: https://github.com/mzp
[@bankair]: https://github.com/bankair
[@crimsonknave]: https://github.com/crimsonknave
[@renuo]: https://github.com/renuo
[@sdeframond]: https://github.com/sdeframond
[@til]: https://github.com/til
[@carhartl]: https://github.com/carhartl
[@dylandavidson]: https://github.com/dylandavidson
[@tmr08c]: https://github.com/tmr08c
[@hbd225]: https://github.com/hbd225
[@l8nite]: https://github.com/l8nite
