Merge pull request rubocop#13253 from Earlopain/cop-cop-deprecation-w…

…arning

Emit a deprecation when custom cops inherit from `RuboCop::Cop::Cop`

changelog/change_deprecation_for_cop_cop_cops.md

@@ -0,0 +1 @@
+* [#13253](https://github.com/rubocop/rubocop/pull/13253): Emit a deprecation when custom cops inherit from `RuboCop::Cop::Cop`. ([@earlopain][])

lib/rubocop/cop/cop.rb

@@ -22,6 +22,14 @@ def call(corrector)
         end
       end
 
+      def self.inherited(_subclass)
+        super
+        warn Rainbow(<<~WARNING).yellow, uplevel: 1
+          Inheriting from `RuboCop::Cop::Cop` is deprecated. Use `RuboCop::Cop::Base` instead.
+          For more information, see https://docs.rubocop.org/rubocop/v1_upgrade_notes.html.
+        WARNING
+      end
+
       def self.support_autocorrect?
         method_defined?(:autocorrect)
       end

spec/rubocop/cop/cop_spec.rb

@@ -233,9 +233,13 @@
 
     context 'when cop supports autocorrection', :restore_registry do
       let(:cop_class) do
-        stub_cop_class('RuboCop::Cop::Test::StubCop', inherit: described_class) do
-          def autocorrect(node); end
-        end
+        cop_class = nil
+        expect do # rubocop:disable RSpec/ExpectInLet
+          cop_class = stub_cop_class('RuboCop::Cop::Test::StubCop', inherit: described_class) do
+            def autocorrect(node); end
+          end
+        end.to output(/Inheriting from `RuboCop::Cop::Cop` is deprecated/).to_stderr
+        cop_class
       end
 
       context 'when offense was corrected' do