### New features

* [#2081](https://github.com/bbatsov/rubocop/pull/2081): New cop `Style/Send` checks for the use of `send` and instead encourages changing it to `BasicObject#__send__` or `Object#public_send` (disabled by default). ([@syndbg][])
* [#2057](https://github.com/bbatsov/rubocop/pull/2057): New cop `Lint/FormatParameterMismatch` checks for a mismatch between the number of fields expected in format/sprintf/% and what was pased to it. ([@edmz][])
* [#2010](https://github.com/bbatsov/rubocop/pull/2010): Add `space` style for SpaceInsideStringInterpolation. ([@gotrevor][])
* [#2007](https://github.com/bbatsov/rubocop/pull/2007): Allow any modifier before `def`, not only visibility modifiers. ([@fphilipe][])
* [#1980](https://github.com/bbatsov/rubocop/pull/1980): `--auto-gen-config` now outputs an excluded files list for failed cops (up to a maxiumum of 15 files). ([@bmorrall][])
* [#2004](https://github.com/bbatsov/rubocop/pull/2004): Introduced `--exclude-limit COUNT` to configure how many files `--auto-gen-config` will exclude. ([@awwaiid][], [@jonas054][])
* [#1918](https://github.com/bbatsov/rubocop/issues/1918): New configuration parameter `AllCops:DisabledByDefault` when set to `true` makes only cops found in user configuration enabled, which makes cop selection *opt-in*. ([@jonas054][])
* New cop `Performance/StringReplacement` checks for usages of `gsub` that can be replaced with `tr` or `delete`. ([@rrosenblum][])
* [#2001](https://github.com/bbatsov/rubocop/issues/2001): New cop `Style/InitialIndentation` checks for indentation of the first non-blank non-comment line in a file. ([@jonas054][])
* [#2060](https://github.com/bbatsov/rubocop/issues/2060): New cop `Style/RescueEnsureAlignment` checks for bad alignment of `rescue` and `ensure` keywords. ([@lumeet][])
* New cop `Style/OptionalArguments` checks for optional arguments that do not appear at the end of an argument list. ([@rrosenblum][])
* New cop `Lint/CircularArgumentReference` checks for "circular argument references" in keyword arguments, which Ruby 2.2 warns against. ([@maxjacobson][], [@sliuu][])
* [#2030](https://github.com/bbatsov/rubocop/issues/2030): New cop `Style/OptionHash` checks for option hashes and encourages changing them to keyword arguments (disabled by default). ([@maxjacobson][])

### Changes

* [#2052](https://github.com/bbatsov/rubocop/pull/2052): `Style/RescueModifier` uses token stream to identify offenses. ([@urbanautomaton][])
* Rename `Rails/Date` and `Rails/TimeZone` style names to "strict" and "flexible" and make "flexible" to be default. ([@palkan][])
* [#2035](https://github.com/bbatsov/rubocop/issues/2035): `Style/ExtraSpacing` is now enabled by default and has a configuration parameter `AllowForAlignment` that is `true` by default, making it allow extra spacing if it's used for alignment purposes. ([@jonas054][])

### Bugs fixed

* [#2014](https://github.com/bbatsov/rubocop/pull/2014): Fix `Style/TrivialAccessors` to support AllowPredicates: false. ([@gotrevor][])
* [#1988](https://github.com/bbatsov/rubocop/issues/1988): Fix bug in `Style/ParallelAssignment` when assigning from `Module::CONSTANT`. ([@rrosenblum][])
* [#1995](https://github.com/bbatsov/rubocop/pull/1995): Improve message for `Rails/TimeZone`. ([@palkan][])
* [#1977](https://github.com/bbatsov/rubocop/issues/1977): Fix bugs in `Rails/Date` and `Rails/TimeZone` when using namespaced Time/Date. ([@palkan][])
* [#1973](https://github.com/bbatsov/rubocop/issues/1973): Do not register an offense in `Performance/Detect` when `select` is called on `Enumerable::Lazy`. ([@palkan][])
* [#2015](https://github.com/bbatsov/rubocop/issues/2015): Fix bug occurring for auto-correction of a misaligned `end` in a file with only one method. ([@jonas054][])
* Allow string interpolation segments inside single quoted string literals when double quotes are preferred. ([@segiddins][])
* [#2026](https://github.com/bbatsov/rubocop/issues/2026): Allow `Time.current` when style is "acceptable".([@palkan][])
* [#2029](https://github.com/bbatsov/rubocop/issues/2029): Fix bug where `Style/RedundantReturn` auto-corrects returning implicit hashes to invalid syntax. ([@rrosenblum][])
* [#2021](https://github.com/bbatsov/rubocop/issues/2021): Fix bug in `Style/BlockDelimiters` when a `semantic` expression is used in an array or a range. ([@lumeet][])
* [#1992](https://github.com/bbatsov/rubocop/issues/1992): Allow parentheses in assignment to a variable with the same name as the method's in `Style/MethodCallParentheses`. ([@lumeet][])
* [#2045](https://github.com/bbatsov/rubocop/issues/2045): Fix crash in `Style/IndentationWidth` when using `private_class_method def self.foo` syntax. ([@unmanbearpig][])
* [#2006](https://github.com/bbatsov/rubocop/issues/2006): Fix crash in `Style/FirstParameterIndentation` in case of nested offenses. ([@unmanbearpig][])
* [#2059](https://github.com/bbatsov/rubocop/issues/2059): Don't check for trivial accessors in modules. ([@bbatsov][])
* Add proper punctuation to the end of offense messages, where it is missing. ([@lumeet][])
* [#2071](https://github.com/bbatsov/rubocop/pull/2071): Keep line breaks in place on WordArray autocorrect.([@unmanbearpig][])
* [#2075](https://github.com/bbatsov/rubocop/pull/2075): Properly correct `Style/PercentLiteralDelimiters` with escape characters in them. ([@rrosenblum][])
* [#2023](https://github.com/bbatsov/rubocop/issues/2023): Avoid auto-correction corruption in `IndentationWidth`. ([@jonas054][])
* [#2080](https://github.com/bbatsov/rubocop/issues/2080): Properly parse code in `Performance/Count` when calling `select..count` in a class that extends an enumerable. ([@rrosenblum][])
* [#2093](https://github.com/bbatsov/rubocop/issues/2093): Fix bug in `Style/OneLineConditional` which should not raise an offense with an 'if/then/end' statement. ([@sliuu][])

[@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