added whitespace toggle to diffs page and set it to return the project compare...

added whitespace toggle to diffs page and set it to return the project compare path with the selected whitespace params

Updated CHANGELOG

Moved CHANGELOG entry

CHANGELOG

@@ -38,6 +38,7 @@ v 8.9.0 (unreleased)
   - Add support for using Yubikeys (U2F) for two-factor authentication
   - Link to blank group icon doesn't throw a 404 anymore
   - Remove 'main language' feature
+  - Toggle whitespace button now available for compare branches diffs #17881
   - Pipelines can be canceled only when there are running builds
   - Use downcased path to container repository as this is expected path by Docker
   - Projects pending deletion will render a 404 page

app/helpers/diff_helper.rb

@@ -135,6 +135,11 @@ module DiffHelper
     toggle_whitespace_link(url, options)
   end
+  def diff_compare_whitespace_link(project, from, to, options)
+    url = namespace_project_compare_path(project.namespace, project, from, to, params_with_whitespace)
+    toggle_whitespace_link(url, options)
+  end
+
   private
   def hide_whitespace?

app/views/projects/diffs/_diffs.html.haml

@@ -11,6 +11,8 @@
         = commit_diff_whitespace_link(@project, @commit, class: 'hidden-xs')
       - elsif current_controller?(:merge_requests)
         = diff_merge_request_whitespace_link(@project, @merge_request, class: 'hidden-xs')
+      - elsif current_controller?(:compare)
+        = diff_compare_whitespace_link(@project, params[:from], params[:to], class: 'hidden-xs')
     .btn-group
       = inline_diff_btn
       = parallel_diff_btn