Fix Style/PerlBackrefs cop

This fixes the Style/PerlBackrefs cop

.rubocop_todo.yml

@@ -638,22 +638,6 @@ Style/ParallelAssignment:
 Style/PercentLiteralDelimiters:
   Enabled: false
 
-# Offense count: 15
-# Cop supports --auto-correct.
-Style/PerlBackrefs:
-  Exclude:
-    - 'app/controllers/projects/application_controller.rb'
-    - 'app/helpers/submodule_helper.rb'
-    - 'lib/backup/manager.rb'
-    - 'lib/banzai/filter/abstract_reference_filter.rb'
-    - 'lib/banzai/filter/autolink_filter.rb'
-    - 'lib/banzai/filter/emoji_filter.rb'
-    - 'lib/banzai/filter/gollum_tags_filter.rb'
-    - 'lib/expand_variables.rb'
-    - 'lib/gitlab/diff/highlight.rb'
-    - 'lib/gitlab/search_results.rb'
-    - 'lib/gitlab/sherlock/query.rb'
-
 # Offense count: 200
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.

app/controllers/projects/application_controller.rb

@@ -58,9 +58,9 @@ class Projects::ApplicationController < ApplicationController
   def method_missing(method_sym, *arguments, &block)
     case method_sym.to_s
     when /\Aauthorize_(.*)!\z/
-      authorize_action!($1.to_sym)
+      authorize_action!(Regexp.last_match(1).to_sym)
     when /\Acheck_(.*)_available!\z/
-      check_project_feature_available!($1.to_sym)
+      check_project_feature_available!(Regexp.last_match(1).to_sym)
     else
       super
     end

app/helpers/submodule_helper.rb

@@ -18,7 +18,7 @@ module SubmoduleHelper
     end
 
     if url =~ %r{([^/:]+)/([^/]+(?:\.git)?)\Z}
-      namespace, project = $1, $2
+      namespace, project = Regexp.last_match(1), Regexp.last_match(2)
       gitlab_hosts = [Gitlab.config.gitlab.url,
                       Gitlab.config.gitlab_shell.ssh_path_prefix]
 

changelogs/unreleased/perl-backref-cop.yml

+---
+title: Fix Style/PerlBackrefs cop
+merge_request: 41246
+author: Rajendra Kadam
+type: fixed

lib/backup/manager.rb

@@ -88,7 +88,7 @@ module Backup
             # - 1495527097_2017_05_23_9.3.0-pre_gitlab_backup.tar
             next unless file =~ /^(\d{10})(?:_\d{4}_\d{2}_\d{2}(_\d+\.\d+\.\d+((-|\.)(pre|rc\d))?(-ee)?)?)?_gitlab_backup\.tar$/
 
-            timestamp = $1.to_i
+            timestamp = Regexp.last_match(1).to_i
 
             if Time.at(timestamp) < (Time.now - keep_time)
               begin

lib/banzai/filter/abstract_reference_filter.rb

@@ -265,7 +265,7 @@ module Banzai
         extras = []
 
         if matches.names.include?("anchor") && matches[:anchor] && matches[:anchor] =~ /\A\#note_(\d+)\z/
-          extras << "comment #{$1}"
+          extras << "comment #{Regexp.last_match(1)}"
         end
 
         extension = matches[:extension] if matches.names.include?("extension")
@@ -436,7 +436,7 @@ module Banzai
         escaped = escape_html_entities(text)
 
         escaped.gsub(REFERENCE_PLACEHOLDER_PATTERN) do |match|
-          placeholder_data[$1.to_i]
+          placeholder_data[Regexp.last_match(1).to_i]
         end
       end
     end

lib/banzai/filter/autolink_filter.rb

@@ -86,7 +86,7 @@ module Banzai
         # outside the link element. The entity must be marked HTML safe in
         # order to be output literally rather than escaped.
         match.gsub!(/((?:&[\w#]+;)+)\z/, '')
-        dropped = ($1 || '').html_safe
+        dropped = (Regexp.last_match(1) || '').html_safe
 
         # To match the behaviour of Rinku, if the matched link ends with a
         # closing part of a matched pair of punctuation, we remove that trailing

lib/banzai/filter/emoji_filter.rb

@@ -33,7 +33,7 @@ module Banzai
       # Returns a String with :emoji: replaced with gl-emoji unicode.
       def emoji_name_element_unicode_filter(text)
         text.gsub(emoji_pattern) do |match|
-          name = $1
+          name = Regexp.last_match(1)
           Gitlab::Emoji.gl_emoji_tag(name)
         end
       end

lib/banzai/filter/gollum_tags_filter.rb

@@ -64,7 +64,7 @@ module Banzai
           next if has_ancestor?(node, IGNORED_ANCESTOR_TAGS)
           next unless node.content =~ TAGS_PATTERN
 
-          html = process_tag($1)
+          html = process_tag(Regexp.last_match(1))
 
           node.replace(html) if html && html != node.content
         end

lib/expand_variables.rb

@@ -7,7 +7,7 @@ module ExpandVariables
 
       value.gsub(/\$([a-zA-Z_][a-zA-Z0-9_]*)|\${\g<1>}|%\g<1>%/) do
         variables_hash ||= transform_variables(variables)
-        variables_hash[$1 || $2]
+        variables_hash[Regexp.last_match(1) || Regexp.last_match(2)]
       end
     end
 

lib/gitlab/diff/highlight.rb

@@ -60,7 +60,7 @@ module Gitlab
         # Only update text if line is found. This will prevent
         # issues with submodules given the line only exists in diff content.
         if rich_line
-          line_prefix = diff_line.text =~ /\A(.)/ ? $1 : ' '
+          line_prefix = diff_line.text =~ /\A(.)/ ? Regexp.last_match(1) : ' '
           "#{line_prefix}#{rich_line}".html_safe
         end
       end

lib/gitlab/search_results.rb

@@ -186,7 +186,7 @@ module Gitlab
         params[:sort] = 'updated_desc'
 
         if query =~ /#(\d+)\z/
-          params[:iids] = $1
+          params[:iids] = Regexp.last_match(1)
         else
           params[:search] = query
         end

lib/gitlab/sherlock/query.rb

@@ -105,7 +105,7 @@ module Gitlab
         query.each_line
           .map { |line| line.strip }
           .join("\n")
-          .gsub(PREFIX_NEWLINE) { "\n#{$1} " }
+          .gsub(PREFIX_NEWLINE) { "\n#{Regexp.last_match(1)} " }
       end
     end
   end