Display flash message to unauthenticated user when creating new issue

app/controllers/projects/issues_controller.rb

@@ -260,4 +260,13 @@ class Projects::IssuesController < Projects::ApplicationController
       :milestone_id, :due_date, :state_event, :task_num, :lock_version, label_ids: []
     )
   end
+
+  def authenticate_user!
+    return if current_user
+
+    notice = "Please sign in to create the new issue."
+
+    store_location_for :user, request.fullpath
+    redirect_to new_user_session_path, notice: notice
+  end
 end

spec/controllers/projects/issues_controller_spec.rb

@@ -90,6 +90,7 @@ describe Projects::IssuesController do
     it 'redirects to signin if not logged in' do
       get :new, namespace_id: project.namespace, project_id: project
 
+      expect(flash[:notice]).to eq 'Please sign in to create the new issue.'
       expect(response).to redirect_to(new_user_session_path)
     end