display referenced merge requests in issue description with CI status

app/assets/stylesheets/pages/issues.scss

@@ -60,6 +60,26 @@ form.edit-issue {
   margin: 0;
 }
 
+.merge-requests-title {
+  font-size: 16px;
+  font-weight: 600;
+}
+
+.merge-request-id {
+  display: inline-block;
+  width: 3em;
+}
+
+.merge-request-info {
+  padding-left: 5px;
+}
+
+.merge-request-status {
+  color: $gl-gray;
+  font-size: 15px;
+  font-weight: bold;
+}
+
 .merge-request,
 .issue {
   &.today {

app/controllers/projects/issues_controller.rb

@@ -62,6 +62,7 @@ class Projects::IssuesController < Projects::ApplicationController
     @note = @project.notes.new(noteable: @issue)
     @notes = @issue.notes.nonawards.with_associations.fresh
     @noteable = @issue
+    @merge_requests = @issue.referenced_merge_requests
 
     respond_with(@issue)
   end

app/helpers/ci_status_helper.rb

@@ -52,7 +52,7 @@ module CiStatusHelper
         'circle'
       end
 
-    icon(icon_name)
+    icon(icon_name + ' fw')
   end
 
   def render_ci_status(ci_commit)

app/models/issue.rb

@@ -83,6 +83,14 @@ class Issue < ActiveRecord::Base
     reference
   end
 
+  def referenced_merge_requests
+    references = [self, *notes].flat_map do |note|
+      note.all_references(load_lazy_references: false).merge_requests
+    end.uniq
+
+    Gitlab::Markdown::ReferenceFilter::LazyReference.load(references).uniq.sort_by(&:iid)
+  end
+
   # Reset issue events cache
   #
   # Since we do cache @event we need to reset cache in special cases:

app/views/projects/issues/_merge_requests.html.haml

@@ -0,0 +1,25 @@
+-if @merge_requests.any?
+  %h2.merge-requests-title
+    = pluralize(@merge_requests.count, 'Related Merge Request')
+  %ul.bordered-list
+    - has_any_ci = @merge_requests.any?(&:ci_commit)
+    - @merge_requests.each do |merge_request|
+      %li
+        %span.merge-request-ci-status
+          - if merge_request.ci_commit
+            = render_ci_status(merge_request.ci_commit)
+          - elsif has_any_ci
+            = icon('blank fw')
+        %span.merge-request-id
+          \##{merge_request.iid}
+        %span.merge-request-info
+          %strong
+            = link_to_gfm merge_request.title, merge_request_path(merge_request), class: "row_title"
+          in
+          - project = merge_request.target_project
+          = link_to project.name_with_namespace, namespace_project_path(project.namespace, project)
+        %span.merge-request-status.prepend-left-10
+          - if merge_request.merged?
+            MERGED
+          - elsif merge_request.closed?
+            CLOSED

app/views/projects/issues/show.html.haml

@@ -47,6 +47,10 @@
                 = markdown(@issue.description, cache_key: [@issue, "description"])
             %textarea.hidden.js-task-list-field
               = @issue.description
+
+    .merge-requests
+      = render 'merge_requests'
+
   - if @closed_by_merge_requests.present?
     = render 'projects/issues/closed_by_box'
   .issue-discussion