Redmine

The following patch will display a "Successful deletion" flash message after deleting issues, documents, news, and wiki pages.
I think that you don't need to display a flash message because the attachments disappear dynamically on the screen when you delete them.

diff --git a/app/controllers/documents_controller.rb b/app/controllers/documents_controller.rb
index b9e2633cc..101e5443a 100644
--- a/app/controllers/documents_controller.rb
+++ b/app/controllers/documents_controller.rb
@@ -83,6 +83,7 @@ class DocumentsController < ApplicationController

   def destroy
     @document.destroy if request.delete?
+    flash[:notice] = l(:notice_successful_delete)
     redirect_to project_documents_path(@project)
   end

diff --git a/app/controllers/issues_controller.rb b/app/controllers/issues_controller.rb
index 0d1acc95b..b442b355b 100644
--- a/app/controllers/issues_controller.rb
+++ b/app/controllers/issues_controller.rb
@@ -448,7 +448,10 @@ class IssuesController < ApplicationController
       end
     end
     respond_to do |format|
-      format.html {redirect_back_or_default _project_issues_path(@project)}
+      format.html {
+        flash[:notice] = l(:notice_successful_delete)
+        redirect_back_or_default _project_issues_path(@project)
+      }
       format.api  {render_api_ok}
     end
   end
diff --git a/app/controllers/news_controller.rb b/app/controllers/news_controller.rb
index 511f10ddb..a67ef88c8 100644
--- a/app/controllers/news_controller.rb
+++ b/app/controllers/news_controller.rb
@@ -115,7 +115,10 @@ class NewsController < ApplicationController
   def destroy
     @news.destroy
     respond_to do |format|
-      format.html { redirect_to project_news_index_path(@project) }
+      format.html {
+        flash[:notice] = l(:notice_successful_delete)
+        redirect_to project_news_index_path(@project)
+      }
       format.api  { render_api_ok }
     end
   end
diff --git a/app/controllers/wiki_controller.rb b/app/controllers/wiki_controller.rb
index 527f0b821..fdb523cb6 100644
--- a/app/controllers/wiki_controller.rb
+++ b/app/controllers/wiki_controller.rb
@@ -284,7 +284,10 @@ class WikiController < ApplicationController
     end
     @page.destroy
     respond_to do |format|
-      format.html { redirect_to project_wiki_index_path(@project) }
+      format.html {
+        flash[:notice] = l(:notice_successful_delete)
+        redirect_to project_wiki_index_path(@project)
+      }
       format.api { render_api_ok }
     end
   end

Setting the target version to 4.2.0.

Committed the patch. Thank you.