Support expanded reference formats for URLs

This allows appending a `+` to issue, MR, and epic URL references so
that their title is rendered in the HTML

Changelog: added

app/models/merge_request.rb

@@ -506,12 +506,12 @@ class MergeRequest < ApplicationRecord
   def self.reference_pattern
     @reference_pattern ||= %r{
       (#{Project.reference_pattern})?
-      #{Regexp.escape(reference_prefix)}(?<merge_request>\d+)(?<format>\+)?
+      #{Regexp.escape(reference_prefix)}#{Gitlab::Regex.merge_request}
     }x
   end
 
   def self.link_reference_pattern
-    @link_reference_pattern ||= super("merge_requests", /(?<merge_request>\d+)/)
+    @link_reference_pattern ||= super("merge_requests", Gitlab::Regex.merge_request)
   end
 
   def self.reference_valid?(reference)

doc/user/markdown.md

@@ -562,7 +562,7 @@ To include the title in the rendered link of an issue, merge request, or epic, a
 at the end of the reference. For example, a reference like `#123+` is rendered as
 `The issue title (#123)`.
 
-Expanding titles does not apply to URL references, like `https://gitlab.com/gitlab-org/gitlab/-/issues/1234`.
+URL references like `https://gitlab.com/gitlab-org/gitlab/-/issues/1234+` are also expanded.
 
 ### Embedding metrics in GitLab Flavored Markdown
 

ee/app/models/ee/epic.rb

@@ -221,7 +221,7 @@ module EE
           }x
           %r{
             (#{group_regexp})?
-            (?:#{combined_prefix})(?<epic>\d+)(?<format>\+)?
+            (?:#{combined_prefix})#{::Gitlab::Regex.epic}
           }x
         end
       end
@@ -236,7 +236,7 @@ module EE
             #{Regexp.escape(::Gitlab.config.gitlab.url)}
             \/groups\/(?<group>#{::Gitlab::PathRegex::FULL_NAMESPACE_FORMAT_REGEX})
             \/-\/epics
-            \/(?<epic>\d+)
+            \/#{::Gitlab::Regex.epic}
             (?<path>
               (\/[a-z0-9_=-]+)*\/*
             )?

ee/lib/ee/gitlab/regex.rb

+# frozen_string_literal: true
+
+module EE
+  module Gitlab
+    module Regex
+      extend ActiveSupport::Concern
+
+      class_methods do
+        def epic
+          @epic ||= /(?<epic>\d+)(?<format>\+)?/
+        end
+      end
+    end
+  end
+end

ee/spec/lib/banzai/filter/references/epic_reference_filter_spec.rb

@@ -72,6 +72,13 @@ RSpec.describe Banzai::Filter::References::EpicReferenceFilter do
       expect(link.attr('data-reference-format')).to eq('+')
     end
 
+    it 'includes a data-reference-format attribute for URL references' do
+      link = doc("#{urls.group_epic_url(group, epic)}+").css('a').first
+
+      expect(link).to have_attribute('data-reference-format')
+      expect(link.attr('data-reference-format')).to eq('+')
+    end
+
     it 'ignores invalid epic IIDs' do
       text = "Check &#{non_existing_record_iid}"
 

lib/banzai/filter/references/reference_filter.rb

@@ -184,7 +184,9 @@ module Banzai
         end
 
         def unescape_link(href)
-          CGI.unescape(href)
+          # We cannot use CGI.unescape here because it also converts `+` to spaces.
+          # We need to keep the `+` for expanded reference formats.
+          Addressable::URI.unescape(href)
         end
 
         def unescape_html_entities(text)

lib/gitlab/regex.rb

@@ -427,6 +427,10 @@ module Gitlab
       @issue ||= /(?<issue>\d+)(?<format>\+)?(?=\W|\z)/
     end
 
+    def merge_request
+      @merge_request ||= /(?<merge_request>\d+)(?<format>\+)?/
+    end
+
     def base64_regex
       @base64_regex ||= %r{(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?}.freeze
     end
@@ -441,3 +445,5 @@ module Gitlab
     end
   end
 end
+
+Gitlab::Regex.prepend_mod

spec/lib/banzai/filter/references/issue_reference_filter_spec.rb

@@ -124,6 +124,14 @@ RSpec.describe Banzai::Filter::References::IssueReferenceFilter do
       expect(link.attr('data-reference-format')).to eq('+')
     end
 
+    it 'includes a data-reference-format attribute for URL references' do
+      doc = reference_filter("Issue #{issue_url}+")
+      link = doc.css('a').first
+
+      expect(link).to have_attribute('data-reference-format')
+      expect(link.attr('data-reference-format')).to eq('+')
+    end
+
     it 'supports an :only_path context' do
       doc = reference_filter("Issue #{reference}", only_path: true)
       link = doc.css('a').first.attr('href')

spec/lib/banzai/filter/references/merge_request_reference_filter_spec.rb

@@ -117,6 +117,14 @@ RSpec.describe Banzai::Filter::References::MergeRequestReferenceFilter do
       expect(link.attr('data-reference-format')).to eq('+')
     end
 
+    it 'includes a data-reference-format attribute for URL references' do
+      doc = reference_filter("Merge #{urls.project_merge_request_url(project, merge)}+")
+      link = doc.css('a').first
+
+      expect(link).to have_attribute('data-reference-format')
+      expect(link.attr('data-reference-format')).to eq('+')
+    end
+
     it 'supports an :only_path context' do
       doc = reference_filter("Merge #{reference}", only_path: true)
       link = doc.css('a').first.attr('href')