[Fix #6641] Specify Performance/RangeInclude as unsafe

Fixes #6641.

This PR specifies `Performance/RangeInclude` as unsafe because
`Range#include?` and `Range#cover?` are not equivalent behaviour.

CHANGELOG.md

@@ -10,6 +10,10 @@
 * [#6617](https://github.com/rubocop-hq/rubocop/issues/6617): Prevent traversal error on infinite ranges. ([@drenmi][])
 * [#6625](https://github.com/rubocop-hq/rubocop/issues/6625): Revert the "auto-exclusion of files ignored by git" feature. ([@bbatsov][])
 
+### Changes
+
+* [#6641](https://github.com/rubocop-hq/rubocop/issues/6641): Specify `Performance/RangeInclude` as unsafe because `Range#include?` and `Range#cover?` are not equivalent. ([@koic][])
+
 ## 0.62.0 (2019-01-01)
 
 ### New features

config/default.yml

@@ -2074,6 +2074,7 @@ Performance/RangeInclude:
   Reference: 'https://github.com/JuanitoFatas/fast-ruby#cover-vs-include-code'
   Enabled: true
   VersionAdded: '0.36'
+  Safe: false
 
 Performance/RedundantBlockCall:
   Description: 'Use `yield` instead of `block.call`.'

lib/rubocop/cop/performance/range_include.rb

@@ -9,6 +9,9 @@ module Performance
       # end points of the `Range`. In a great majority of cases, this is what
       # is wanted.
       #
+      # This cop is `Safe: false` by default because `Range#include?` and
+      # `Range#cover?` are not equivalent behaviour.
+      #
       # @example
       #   # bad
       #   ('a'..'z').include?('b') # => true

manual/cops_performance.md

@@ -515,14 +515,17 @@ end
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
 --- | --- | --- | --- | ---
-Enabled | Yes | Yes  | 0.36 | -
+Enabled | No | Yes  | 0.36 | -
 
 This cop identifies uses of `Range#include?`, which iterates over each
 item in a `Range` to see if a specified item is there. In contrast,
 `Range#cover?` simply compares the target item with the beginning and
 end points of the `Range`. In a great majority of cases, this is what
 is wanted.
 
+This cop is `Safe: false` by default because `Range#include?` and
+`Range#cover?` are not equivalent behaviour.
+
 ### Examples
 
 ```ruby