### New features

* [#3560](https://github.com/rubocop/rubocop/pull/3560): Add a configuration option `empty_lines_except_namespace` to `Style/EmptyLinesAroundClassBody` and `Style/EmptyLinesAroundModuleBody`. ([@legendetm][])
* [#3370](https://github.com/rubocop/rubocop/issues/3370): Add new `Rails/HttpPositionalArguments` cop to check your Rails 5 test code for existence of positional args usage. ([@logicminds][])
* [#3510](https://github.com/rubocop/rubocop/issues/3510): Add a configuration option, `ConvertCodeThatCanStartToReturnNil`, to `Style/SafeNavigation` to check for code that could start returning `nil` if safe navigation is used. ([@rrosenblum][])
* Add a new `AllCops/StyleGuideBaseURL` setting that allows the use of relative paths and/or fragments within each cop's `StyleGuide` setting, to make forking of custom style guides easier. ([@scottmatthewman][])
* [#3566](https://github.com/rubocop/rubocop/issues/3566): Add new `Metric/BlockLength` cop to ensure blocks don't get too long. ([@savef][])
* [#3428](https://github.com/rubocop/rubocop/issues/3428): Add support for configuring `Style/PreferredHashMethods` with either `short` or `verbose` style method names. ([@abrom][])
* [#3455](https://github.com/rubocop/rubocop/issues/3455): Add new `Rails/DynamicFindBy` cop. ([@pocke][])
* [#3542](https://github.com/rubocop/rubocop/issues/3542): Add a configuration option, `IgnoreCopDirectives`, to `Metrics/LineLength` to stop cop directives (`# rubocop:disable Metrics/AbcSize`) from being counted when considering line length. ([@jmks][])
* Add new `Rails/DelegateAllowBlank` cop. ([@connorjacobsen][])
* Add new `Style/MultilineMemoization` cop. ([@drenmi][])

### Bug fixes

* [#3103](https://github.com/rubocop/rubocop/pull/3103): Make `Style/ExtraSpacing` cop register an offense for extra spaces present in single-line hash literals. ([@tcdowney][])
* [#3513](https://github.com/rubocop/rubocop/pull/3513): Fix false positive in `Style/TernaryParentheses` for a ternary with ranges. ([@dreyks][])
* [#3520](https://github.com/rubocop/rubocop/issues/3520): Fix regression causing `Lint/AssignmentInCondition` false positive. ([@savef][])
* [#3514](https://github.com/rubocop/rubocop/issues/3514): Make `Style/VariableNumber` cop not register an offense when valid normal case variable names have an integer after the first `_`. ([@b-t-g][])
* [#3516](https://github.com/rubocop/rubocop/issues/3516): Make `Style/VariableNumber` cop not register an offense when valid normal case variable names have an integer in the middle. ([@b-t-g][])
* [#3436](https://github.com/rubocop/rubocop/issues/3436): Make `Rails/SaveBang` cop not register an offense when return value of a non-bang method is returned by the parent method. ([@coorasse][])
* [#3540](https://github.com/rubocop/rubocop/issues/3540): Fix `Style/GuardClause` to register offense for instance and singleton methods. ([@tejasbubane][])
* [#3311](https://github.com/rubocop/rubocop/issues/3311): Detect incompatibilities with the external encoding to prevent bad autocorrections in `Style/StringLiterals`. ([@deivid-rodriguez][])
* [#3499](https://github.com/rubocop/rubocop/issues/3499): Ensure `Lint/UnusedBlockArgument` doesn't make recommendations that would change arity for methods defined using `#define_method`. ([@drenmi][])
* [#3430](https://github.com/rubocop/rubocop/issues/3430): Fix exception in `Performance/RedundantMerge` when inspecting a `#merge!` with implicit receiver. ([@drenmi][])
* [#3411](https://github.com/rubocop/rubocop/issues/3411): Avoid auto-correction crash for single `when` in `Performance/CaseWhenSplat`. ([@jonas054][])
* [#3286](https://github.com/rubocop/rubocop/issues/3286): Allow `self.a, self.b = b, a` in `Style/ParallelAssignment`. ([@jonas054][])
* [#3419](https://github.com/rubocop/rubocop/issues/3419): Report offense for `unless x.nil?` in `Style/NonNilCheck` if `IncludeSemanticChanges` is `true`. ([@jonas054][])
* [#3382](https://github.com/rubocop/rubocop/issues/3382): Avoid auto-correction crash for multiple elsifs in `Style/EmptyElse`. ([@lumeet][])
* [#3334](https://github.com/rubocop/rubocop/issues/3334): Do not register an offense for a literal space (`\s`) in `Style/UnneededCapitalW`. ([@rrosenblum][])
* [#3390](https://github.com/rubocop/rubocop/issues/3390): Fix SaveBang cop for multiple conditional. ([@tejasbubane][])
* [#3577](https://github.com/rubocop/rubocop/issues/3577): Fix `Style/RaiseArgs` not allowing compact raise with splatted args. ([@savef][])
* [#3578](https://github.com/rubocop/rubocop/issues/3578): Fix safe navigation method call counting in `Metrics/AbcSize`. ([@savef][])
* [#3592](https://github.com/rubocop/rubocop/issues/3592): Fix `Style/RedundantParentheses` for indexing with literals. ([@thegedge][])
* [#3597](https://github.com/rubocop/rubocop/issues/3597): Fix the autocorrect of `Performance/CaseWhenSplat` when trying to rearrange splat expanded variables to the end of a when condition. ([@rrosenblum][])

### Changes

* [#3512](https://github.com/rubocop/rubocop/issues/3512): Change error message of `Lint/UnneededSplatExpansion` for array in method parameters. ([@tejasbubane][])
* [#3510](https://github.com/rubocop/rubocop/issues/3510): Fix some issues with `Style/SafeNavigation`. Fix auto-correct of multiline if expressions, and do not register an offense for scenarios using `||` and ternary expression. ([@rrosenblum][])
* [#3503](https://github.com/rubocop/rubocop/issues/3503): Change misleading message of `Style/EmptyLinesAroundAccessModifier`. ([@bquorning][])
* [#3407](https://github.com/rubocop/rubocop/issues/3407): Turn off autocorrect for unsafe rules by default. ([@ptarjan][])
* [#3521](https://github.com/rubocop/rubocop/issues/3521): Turn off autocorrect for `Security/JSONLoad` by default. ([@savef][])
* [#2903](https://github.com/rubocop/rubocop/issues/2903): `Style/RedundantReturn` looks for redundant `return` inside conditional branches. ([@lumeet][])

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[@jonas054]: https://github.com/jonas054
[@yujinakayama]: https://github.com/yujinakayama
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[@claco]: http://github.com/claco
[@rifraf]: http://github.com/rifraf
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[@jeremyolliver]: https://github.com/jeremyolliver
[@hannestyden]: https://github.com/hannestyden
[@geniou]: https://github.com/geniou
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[@tmorris-fiksu]: https://github.com/tmorris-fiksu
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[@toy]: https://github.com/toy
[@Koronen]: https://github.com/Koronen
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[@mattjmcnaughton]: https://github.com/mattjmcnaughton
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[@DNNX]: https://github.com/DNNX
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[@prsimp]: https://github.com/prsimp
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[@Fryguy]: https://github.com/Fryguy
[@mikegee]: https://github.com/mikegee
[@tbrisker]: https://github.com/tbrisker
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[@bolshakov]: https://github.com/bolshakov
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[@gylaz]: https://github.com/gylaz
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[@deivid-rodriguez]: https://github.com/deivid-rodriguez
[@pclalv]: https://github.com/pclalv
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[@Tei]: https://github.com/Tei
[@haziqhafizuddin]: https://github.com/haziqhafizuddin
[@dvandersluis]: https://github.com/dvandersluis
[@QuinnHarris]: https://github.com/QuinnHarris
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[@abrom]: https://github.com/abrom
[@thegedge]: https://github.com/thegedge
[@jmks]: https://github.com/jmks/
[@connorjacobsen]: https://github.com/connorjacobsen
[@legendetm]: https://github.com/legendetm
