Trim extra displayed carriage returns in diffs and files with CRLFs

Closes #20440

CHANGELOG

@@ -44,6 +44,7 @@ v 8.10.3 (unreleased)
   - Properly abort a merge when merge conflicts occur
   - Ignore invalid IPs in X-Forwarded-For when trusted proxies are configured.
   - Fix Import/Export issue importing milestones and labels not associated properly
+  - Trim extra displayed carriage returns in diffs and files with CRLFs
 
 v 8.10.2
   - User can now search branches by name. !5144

lib/rouge/formatters/html_gitlab.rb

@@ -18,7 +18,7 @@ module Rouge
           is_first = false
 
           yield %(<span id="LC#{@line_number}" class="line">)
-          line.each { |token, value| yield span(token, value) }
+          line.each { |token, value| yield span(token, value.chomp) }
           yield %(</span>)
 
           @line_number += 1

spec/lib/gitlab/highlight_spec.rb

@@ -17,6 +17,18 @@ describe Gitlab::Highlight, lib: true do
       expect(lines[21]).to eq(%Q{<span id="LC22" class="line">    <span class="k">unless</span> <span class="no">File</span><span class="p">.</span><span class="nf">directory?</span><span class="p">(</span><span class="n">path</span><span class="p">)</span></span>\n})
       expect(lines[26]).to eq(%Q{<span id="LC27" class="line">    <span class="vi">@cmd_status</span> <span class="o">=</span> <span class="mi">0</span></span>\n})
     end
+
+    describe 'with CRLF' do
+      let(:branch) { 'crlf-diff' }
+      let(:blob) { repository.blob_at_branch(branch, path) }
+      let(:lines) do
+        Gitlab::Highlight.highlight_lines(project.repository, 'crlf-diff-test', 'files/whitespace')
+      end
+
+      it 'strips extra LFs' do
+        expect(lines[0]).to eq("<span id=\"LC1\" class=\"line\">test  </span>")
+      end
+    end
   end
 
   describe 'custom highlighting from .gitattributes' do

spec/support/test_env.rb

@@ -21,7 +21,8 @@ module TestEnv
     'expand-collapse-diffs' => '4842455',
     'expand-collapse-files' => '025db92',
     'expand-collapse-lines' => '238e82d',
-    'video'                 => '8879059'
+    'video'                 => '8879059',
+    'crlf-diff'             => '5938907'
   }
 
   # gitlab-test-fork is a fork of gitlab-fork, but we don't necessarily