### New features

* [#3600](https://github.com/rubocop/rubocop/issues/3600): Add new `Bundler/DuplicatedGem` cop. ([@jmks][])
* [#3624](https://github.com/rubocop/rubocop/pull/3624): Add new configuration option `empty_lines_special` to `Style/EmptyLinesAroundClassBody` and `Style/EmptyLinesAroundModuleBody`. ([@legendetm][])
* Add new `Style/EmptyMethod` cop. ([@drenmi][])
* `Style/EmptyLiteral` will now auto-correct `Hash.new` when it is the first argument being passed to a method. The arguments will be wrapped with parenthesis. ([@rrosenblum][])
* [#3713](https://github.com/rubocop/rubocop/pull/3713): Respect `DisabledByDefault` in parent configs. ([@aroben][])
* New cop `Rails/EnumUniqueness` checks for duplicate values defined in enum config. ([@olliebennett][])
* New cop `Rails/EnumUniqueness` checks for duplicate values defined in enum config hash. ([@olliebennett][])
* [#3451](https://github.com/rubocop/rubocop/issues/3451): Add new `require_parentheses_when_complex` style to `Style/TernaryParentheses` cop. ([@swcraig][])
* [#3600](https://github.com/rubocop/rubocop/issues/3600): Add new `Bundler/OrderedGems` cop. ([@tdeo][])
* [#3479](https://github.com/rubocop/rubocop/issues/3479): Add new configuration option `IgnoredPatterns` to `Metrics/LineLength`. ([@jonas054][])

### Changes

* The offense range for `Performance/FlatMap` now includes any parameters that are passed to `flatten`. ([@rrosenblum][])
* [#1747](https://github.com/rubocop/rubocop/issues/1747): Update `Style/SpecialGlobalVars` messages with a reminder to `require 'English'`. ([@ivanovaleksey][])
* Checks `binding.irb` call by `Lint/Debugger` cop. ([@pocke][])
* [#3742](https://github.com/rubocop/rubocop/pull/3742): Checks `min` and `max` call by `Performance/CompareWithBlock` cop. ([@pocke][])

### Bug fixes

* [#3662](https://github.com/rubocop/rubocop/issues/3662): Fix the auto-correction of `Lint/UnneededSplatExpansion` when the splat expansion is inside of another array. ([@rrosenblum][])
* [#3699](https://github.com/rubocop/rubocop/issues/3699): Fix false positive in `Style/VariableNumber` on variable names ending with an underscore. ([@bquorning][])
* [#3687](https://github.com/rubocop/rubocop/issues/3687): Fix the fact that `Style/TernaryParentheses` cop claims to correct uncorrected offenses. ([@Ana06][])
* [#3568](https://github.com/rubocop/rubocop/issues/3568): Fix `--auto-gen-config` behavior for `Style/VariableNumber`. ([@jonas054][])
* Add `format` as an acceptable keyword argument for `Rails/HttpPositionalArguments`. ([@aesthetikx][])
* [#3598](https://github.com/rubocop/rubocop/issues/3598): In `Style/NumericPredicate`, don't report `x != 0` or `x.nonzero?` as the expressions have different values. ([@jonas054][])
* [#3690](https://github.com/rubocop/rubocop/issues/3690): Do not register an offense for multiline braces with content in `Style/SpaceInsideBlockBraces`. ([@rrosenblum][])
* [#3746](https://github.com/rubocop/rubocop/issues/3746): `Lint/NonLocalExitFromIterator` does not warn about `return` in a block which is passed to `Object#define_singleton_method`. ([@AlexWayfer][])

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[@QuinnHarris]: https://github.com/QuinnHarris
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[@aesthetikx]: https://github.com/aesthetikx
[@tdeo]: https://github.com/tdeo
[@AlexWayfer]: https://github.com/AlexWayfer
