1 files changed, 71 insertions, 0 deletions
diff --git a/rubocop/cop/lint/last_keyword_argument.rb b/rubocop/cop/lint/last_keyword_argument.rb
new file mode 100644
index 00000000000..430ea66e9a1
--- /dev/null
+++ b/rubocop/cop/lint/last_keyword_argument.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Lint
+      # This cop only works if there are files from deprecation_toolkit. You can
+      # generate these files by:
+      #
+      # 1. Running specs with RECORD_DEPRECATIONS=1
+      # 1. Downloading the complete set of deprecations/ files from a CI
+      # pipeline (see https://gitlab.com/gitlab-org/gitlab/-/merge_requests/47720)
+      class LastKeywordArgument < Cop
+        MSG = 'Using the last argument as keyword parameters is deprecated'.freeze
+
+        DEPRECATIONS_GLOB = File.expand_path('../../../deprecations/**/*.yml', __dir__)
+        KEYWORD_DEPRECATION_STR = 'maybe ** should be added to the call'
+
+        def on_send(node)
+          arg = node.arguments.last
+          return unless arg
+
+          return unless known_match?(processed_source.file_path, node.first_line, node.method_name.to_s)
+
+          return if arg.children.first.respond_to?(:kwsplat_type?) && arg.children.first&.kwsplat_type?
+
+          # parser thinks `a: :b, c: :d` is hash type, it's actually kwargs
+          return if arg.hash_type? && !arg.source.match(/\A{/)
+
+          add_offense(arg)
+        end
+
+        def autocorrect(arg)
+          lambda do |corrector|
+            if arg.hash_type?
+              kwarg = arg.source.sub(/\A{\s*/, '').sub(/\s*}\z/, '')
+              corrector.replace(arg, kwarg)
+            elsif arg.splat_type?
+              corrector.insert_before(arg, '*')
+            else
+              corrector.insert_before(arg, '**')
+            end
+          end
+        end
+
+        private
+
+        def known_match?(file_path, line_number, method_name)
+          file_path_from_root = file_path.sub(File.expand_path('../../..', __dir__), '')
+
+          method_name = 'initialize' if method_name == 'new'
+
+          self.class.keyword_warnings.any? do |warning|
+            warning.include?("#{file_path_from_root}:#{line_number}") && warning.include?("called method `#{method_name}'")
+          end
+        end
+
+        def self.keyword_warnings
+          @keyword_warnings ||= keywords_list
+        end
+
+        def self.keywords_list
+          hash = Dir.glob(DEPRECATIONS_GLOB).each_with_object({}) do |file, hash|
+            hash.merge!(YAML.safe_load(File.read(file)))
+          end
+
+          hash.values.flatten.select { |str| str.include?(KEYWORD_DEPRECATION_STR) }.uniq
+        end
+      end
+    end
+  end
+end