Apart from the usual myriad of bugfixes, improvements and new cops,
this version introduces a results caching functionality. This
functionality will speed up tremendously consecutive RuboCop runs on
the same codebase.

Another news to share with you - the project now has a crowdfunding
campaign [here](https://salt.bountysource.com/). If you like RuboCop
you might consider supporting its development.

Enjoy!

### New features

* [#2143](https://github.com/bbatsov/rubocop/pull/2143): New cop `Performance/CaseWhenSplat` will identify and rearange `case` `when` statements that contain a `when` condition with a splat. ([@rrosenblum][])
* New cop `Lint/DuplicatedKey` checks for duplicated keys in hashes, which Ruby 2.2 warns against. ([@sliuu][])
* [#2106](https://github.com/bbatsov/rubocop/issues/2106): Add `SuspiciousParamNames` option to `Style/OptionHash`. ([@wli][])
* [#2193](https://github.com/bbatsov/rubocop/pull/2193): `Style/Next` supports more `Enumerable` methods. ([@rrosenblum][])
* [#2179](https://github.com/bbatsov/rubocop/issues/2179): Add `--list-target-files` option to CLI, which prints the files which will be inspected. ([@maxjacobson][])
* New cop `Style/MutableConstant` checks for assignment of mutable objects to constants. ([@bbatsov][])
* New cop `Style/RedudantFreeze` checks for usages of `Object#freeze` on immutable objects. ([@bbatsov][])
* [#1924](https://github.com/bbatsov/rubocop/issues/1924): New option `--cache` and configuration parameter `AllCops: UseCache` turn result caching on (default) or off. ([@jonas054][])
* [#2204](https://github.com/bbatsov/rubocop/pull/2204): New cop `Style/StringMethods` will check for preferred method `to_sym` over `intern`. ([@imtayadeway][])

### Changes

* [#1351](https://github.com/bbatsov/rubocop/issues/1351): Allow class emitter methods in `Style/MethodName`. ([@jonas054][])
* [#2126](https://github.com/bbatsov/rubocop/pull/2126): `Style/RescueModifier` can now auto-correct. ([@rrosenblum][])
* [#2109](https://github.com/bbatsov/rubocop/issues/2109): Allow alignment with a token on the nearest line with same indentation in `Style/ExtraSpacing`. ([@jonas054][])
* `Lint/EndAlignment` handles the `case` keyword. ([@lumeet][])
* [#2146](https://github.com/bbatsov/rubocop/pull/2146): Add STDIN support. ([@caseywebdev][])
* [#2175](https://github.com/bbatsov/rubocop/pull/2175): Files that are excluded from a cop (e.g. using the `Exclude:` config option) are no longer being processed by that cop. ([@bquorning][])
* `Rails/ActionFilter` now handles complete list of methods found in the Rails 4.2 [release notes](https://github.com/rails/rails/blob/4115a12da1409c753c747fd4bab6e612c0c6e51a/guides/source/4_2_release_notes.md#notable-changes-1). ([@MGerrior][])
* [*2138](https://github.com/bbatsov/rubocop/issues/2138): Change the offense in `Style/Next` to highlight the condition instead of the iteration. ([@rrosenblum][])
* `Style/EmptyLineBetweenDefs` now handles class methods as well. ([@unmanbearpig][])
* Improve handling of `super` in `Style/SymbolProc`. ([@lumeet][])
* `Style/SymbolProc` is applied to methods receiving arguments. ([@lumeet][])
* [#1839](https://github.com/bbatsov/rubocop/issues/1839): Remove Rainbow monkey patching of String which conflicts with other gems like colorize. ([@daviddavis][])
* `Style/HashSyntax` is now a bit faster when checking Ruby 1.9 syntax hash keys. ([@bquorning][])
* `Lint/DeprecatedClassMethods` is now a whole lot faster. ([@bquorning][])
* `Lint/BlockAlignment`, `Style/IndentationWidth`, and `Style/MultilineOperationIndentation` are now quite a bit faster. ([@bquorning][])

### Bug Fixes

* [#2123](https://github.com/bbatsov/rubocop/pull/2123): Fix handing of dynamic widths `Lint/FormatParameterMismatch`. ([@edmz][])
* [#2116](https://github.com/bbatsov/rubocop/pull/2116): Fix named params (using hash) `Lint/FormatParameterMismatch`. ([@edmz][])
* [#2135](https://github.com/bbatsov/rubocop/issues/2135): Ignore `super` and `zsuper` nodes in `Style/SymbolProc`. ([@bbatsov][])
* [#2165](https://github.com/bbatsov/rubocop/issues/2165): Fix a NPE in `Style/Alias`. ([@bbatsov][])
* [#2168](https://github.com/bbatsov/rubocop/issues/2168): Fix a NPE in `Rails/TimeZone`. ([@bbatsov][])
* [#2169](https://github.com/bbatsov/rubocop/issues/2169): Fix a NPE in `Rails/Date`. ([@bbatsov][])
* [#2105](https://github.com/bbatsov/rubocop/pull/2105): Fix a warning that was thrown when enabling `Style/OptionHash`. ([@wli][])
* [#2107](https://github.com/bbatsov/rubocop/pull/2107): Fix auto-correct of `Style/ParallelAssignment` for nested expressions. ([@rrosenblum][])
* [#2111](https://github.com/bbatsov/rubocop/issues/2111): Deal with byte order mark in `Style/InitialIndentation`. ([@jonas054][])
* [#2113](https://github.com/bbatsov/rubocop/issues/2113): Handle non-string tokens in `Style/ExtraSpacing`. ([@jonas054][])
* [#2129](https://github.com/bbatsov/rubocop/issues/2129): Handle empty interpolations in `Style/SpaceInsideStringInterpolation`. ([@lumeet][])
* [#2119](https://github.com/bbatsov/rubocop/issues/2119): Do not raise an error in `Style/RescueEnsureAlignment` and `Style/RescueModifier` when processing an excluded file. ([@rrosenblum][])
* [#2149](https://github.com/bbatsov/rubocop/issues/2149): Do not register an offense in `Rails/Date` when `Date#to_time` is called with a time zone argument. ([@maxjacobson][])
* Do not register a `Rails/TimeZone` offense when using Time.new safely. ([@maxjacobson][])
* [#2124](https://github.com/bbatsov/rubocop/issues/2124): Fix bug in `Style/EmptyLineBetweenDefs` when there are only comments between method definitions. ([@lumeet][])
* [#2154](https://github.com/bbatsov/rubocop/issues/2154): `Performance/StringReplacement` can auto-correct replacements with backslash in them. ([@rrosenblum][])
* [#2009](https://github.com/bbatsov/rubocop/issues/2009): Fix bug in `RuboCop::ConfigLoader.load_file` when `safe_yaml` is required. ([@eitoball][])
* [#2155](https://github.com/bbatsov/rubocop/issues/2155): Configuration `EndAlignment: AlignWith: variable` only applies when the operands of `=` are on the same line. ([@jonas054][])
* Fix bug in `Style/IndentationWidth` when `rescue` or `ensure` is preceded by an empty body. ([@lumeet][])
* [#2183](https://github.com/bbatsov/rubocop/issues/2183): Fix bug in `Style/BlockDelimiters` when auto-correcting adjacent braces. ([@lumeet][])
* [#2199](https://github.com/bbatsov/rubocop/issues/2199): Make `rubocop` exit with error when there are only `Lint/UnneededDisable` offenses. ([@jonas054][])
* Fix handling of empty parentheses when auto-correcting in `Style/SymbolProc`. ([@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
[@sumeet]: https://github.com/sumeet
[@ojab]: https://github.com/ojab
[@chastell]: https://github.com/chastell
[@glasnt]: https://github.com/glasnt
[@crazydog115]: https://github.com/crazydog115
[@RGBD]: https://github.com/RGBD
[@panthomakos]: https://github.com/panthomakos
[@matugm]: https://github.com/matugm
[@m1foley]: https://github.com/m1foley
[@tejasbubane]: https://github.com/tejasbubane
[@bmorrall]: https://github.com/bmorrall
[@fphilipe]: https://github.com/fphilipe
[@gotrevor]: https://github.com/gotrevor
[@awwaiid]: https://github.com/awwaiid
[@segiddins]: https://github.com/segiddins
[@urbanautomaton]: https://github.com/urbanautomaton.com
[@unmanbearpig]: https://github.com/unmanbearpig
[@maxjacobson]: https://github.com/maxjacobson
[@sliuu]: https://github.com/sliuu
[@edmz]: https://github.com/edmz
[@syndbg]: https://github.com/syndbg
[@wli]: https://github.com/wli
[@caseywebdev]: https://github.com/caseywebdev
[@MGerrior]: https://github.com/MGerrior
[@imtayadeway]: https://github.com/imtayadeway