Remove sort_diffs feature flag

It was already enabled on production for more than a month now
and no performance degradation was encountered.

Changelog: other

app/models/merge_request_diff.rb

@@ -754,7 +754,6 @@ class MergeRequestDiff < ApplicationRecord
   end
 
   def reorder_diff_files!
-    return unless sort_diffs?
     return if sorted? || merge_request_diff_files.empty?
 
     diff_files = sort_diffs(merge_request_diff_files)
@@ -773,14 +772,8 @@ class MergeRequestDiff < ApplicationRecord
   end
 
   def sort_diffs(diffs)
-    return diffs unless sort_diffs?
-
     Gitlab::Diff::FileCollectionSorter.new(diffs).sort
   end
-
-  def sort_diffs?
-    Feature.enabled?(:sort_diffs, project, default_enabled: :yaml)
-  end
 end
 
 MergeRequestDiff.prepend_if_ee('EE::MergeRequestDiff')

changelogs/unreleased/321937-remove-sort-diffs-ff.yml

+---
+title: Remove sort_diffs feature flag
+merge_request: 61440
+author:
+type: other

config/feature_flags/development/sort_diffs.yml

----
-name: sort_diffs
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/49118
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/293819
-milestone: '13.7'
-type: development
-group: group::code review
-default_enabled: true

lib/gitlab/diff/file_collection/base.rb

@@ -117,8 +117,6 @@ module Gitlab
         end
 
         def sort_diffs(diffs)
-          return diffs unless Feature.enabled?(:sort_diffs, project, default_enabled: :yaml)
-
           Gitlab::Diff::FileCollectionSorter.new(diffs).sort
         end
       end

spec/models/merge_request_diff_spec.rb

@@ -485,27 +485,6 @@ RSpec.describe MergeRequestDiff do
             'files/whitespace'
           ])
         end
-
-        context 'when sort_diffs feature flag is disabled' do
-          before do
-            stub_feature_flags(sort_diffs: false)
-          end
-
-          it 'does not sort diff files directory first' do
-            expect(diff_with_commits.diffs_in_batch(1, 10, diff_options: diff_options).diff_file_paths).to eq([
-              '.DS_Store',
-              '.gitattributes',
-              '.gitignore',
-              '.gitmodules',
-              'CHANGELOG',
-              'README',
-              'bar/branch-test.txt',
-              'custom-highlighting/test.gitlab-custom',
-              'encoding/iso8859.txt',
-              'files/.DS_Store'
-            ])
-          end
-        end
       end
     end
 
@@ -581,37 +560,6 @@ RSpec.describe MergeRequestDiff do
             'gitlab-shell'
           ])
         end
-
-        context 'when sort_diffs feature flag is disabled' do
-          before do
-            stub_feature_flags(sort_diffs: false)
-          end
-
-          it 'does not sort diff files directory first' do
-            expect(diff_with_commits.diffs(diff_options).diff_file_paths).to eq([
-              '.DS_Store',
-              '.gitattributes',
-              '.gitignore',
-              '.gitmodules',
-              'CHANGELOG',
-              'README',
-              'bar/branch-test.txt',
-              'custom-highlighting/test.gitlab-custom',
-              'encoding/iso8859.txt',
-              'files/.DS_Store',
-              'files/images/wm.svg',
-              'files/js/commit.coffee',
-              'files/lfs/lfs_object.iso',
-              'files/ruby/popen.rb',
-              'files/ruby/regex.rb',
-              'files/whitespace',
-              'foo/bar/.gitkeep',
-              'gitlab-grack',
-              'gitlab-shell',
-              'with space/README.md'
-            ])
-          end
-        end
       end
     end
 
@@ -718,40 +666,6 @@ RSpec.describe MergeRequestDiff do
         ])
       end
 
-      context 'when sort_diffs feature flag is disabled' do
-        before do
-          stub_feature_flags(sort_diffs: false)
-        end
-
-        it 'persists diff files unsorted by directory first' do
-          mr_diff = create(:merge_request).merge_request_diff
-          diff_files_paths = mr_diff.merge_request_diff_files.map { |file| file.new_path.presence || file.old_path }
-
-          expect(diff_files_paths).to eq([
-            '.DS_Store',
-            '.gitattributes',
-            '.gitignore',
-            '.gitmodules',
-            'CHANGELOG',
-            'README',
-            'bar/branch-test.txt',
-            'custom-highlighting/test.gitlab-custom',
-            'encoding/iso8859.txt',
-            'files/.DS_Store',
-            'files/images/wm.svg',
-            'files/js/commit.coffee',
-            'files/lfs/lfs_object.iso',
-            'files/ruby/popen.rb',
-            'files/ruby/regex.rb',
-            'files/whitespace',
-            'foo/bar/.gitkeep',
-            'gitlab-grack',
-            'gitlab-shell',
-            'with space/README.md'
-          ])
-        end
-      end
-
       it 'expands collapsed diffs before saving' do
         mr_diff = create(:merge_request, source_branch: 'expand-collapse-lines', target_branch: 'master').merge_request_diff
         diff_file = mr_diff.merge_request_diff_files.find_by(new_path: 'expand-collapse/file-5.txt')

spec/support/shared_examples/lib/gitlab/diff_file_collections_shared_examples.rb

@@ -166,16 +166,6 @@ shared_examples_for 'sortable diff files' do
       it 'returns sorted diff files' do
         expect(raw_diff_files_paths).to eq(sorted_diff_files_paths)
       end
-
-      context 'when sort_diffs feature flag is disabled' do
-        before do
-          stub_feature_flags(sort_diffs: false)
-        end
-
-        it 'returns unsorted diff files' do
-          expect(raw_diff_files_paths).to eq(unsorted_diff_files_paths)
-        end
-      end
     end
   end
 end