[Fix #8901] Fix a false positive for `Naming/BinaryOperatorParameterN…

…ame`

Defining the match operator `=~` triggered a false positive for
`Naming/BinaryOperatorParameterName`, which should not be triggered
for pattern/matchable relations according to the [Ruby style guide](https://rubystyle.guide/#other-arg).

CHANGELOG.md

@@ -17,6 +17,7 @@
 * [#8490](https://github.com/rubocop-hq/rubocop/pull/8490): **(Breaking)** Change logic for cop department name computation. Cops inside deep namespaces (5 or more levels deep) now belong to departments with names that are calculated by joining module names starting from the third one with slashes as separators. For example, cop `Rubocop::Cop::Foo::Bar::Baz` now belongs to `Foo/Bar` department (previously it was `Bar`). ([@dsavochkin][])
 * [#8692](https://github.com/rubocop-hq/rubocop/pull/8692): Default changed to disallow `Layout/TrailingWhitespace` in heredoc. ([@marcandre][])
 * [#8894](https://github.com/rubocop-hq/rubocop/issues/8894): Make `Security/Open` aware of `URI.open`. ([@koic][])
+* [#8901](https://github.com/rubocop-hq/rubocop/issues/8901): Fix false positive for `Naming/BinaryOperatorParameterName` when defining `=~`. ([@zajn][])
 
 ## 0.93.1 (2020-10-12)
 
@@ -4998,3 +4999,4 @@
 [@ghiculescu]: https://github.com/ghiculescu
 [@hatkyinc2]: https://github.com/hatkyinc2
 [@AllanSiqueira]: https://github.com/allansiqueira
+[@zajn]: https://github.com/zajn

lib/rubocop/cop/naming/binary_operator_parameter_name.rb

@@ -18,7 +18,7 @@ class BinaryOperatorParameterName < Base
               'name its argument `other`.'
 
         OP_LIKE_METHODS = %i[eql? equal?].freeze
-        EXCLUDED = %i[+@ -@ [] []= << === `].freeze
+        EXCLUDED = %i[+@ -@ [] []= << === ` =~].freeze
 
         def_node_matcher :op_method_candidate?, <<~PATTERN
           (def [#op_method? $_] (args $(arg [!:other !:_other])) _)

spec/rubocop/cop/naming/binary_operator_parameter_name_spec.rb

@@ -99,4 +99,10 @@ def *(a, b); end # Quite strange, but legal ruby.
       def `(cmd); end
     RUBY
   end
+
+  it 'does not register an offense for the match operator' do
+    expect_no_offenses(<<~RUBY)
+      def =~(regexp); end
+    RUBY
+  end
 end