Dont show comment on diff if diff line was changed after comment left

app/helpers/commits_helper.rb

@@ -38,6 +38,8 @@ module CommitsHelper
 
     lines_arr = ::Gitlab::InlineDiff.processing diff_arr
     lines_arr.each do |line|
+      raw_line = line.dup
+
       next if line.match(/^\-\-\- \/dev\/null/)
       next if line.match(/^\+\+\+ \/dev\/null/)
       next if line.match(/^\-\-\- a/)
@@ -58,7 +60,7 @@ module CommitsHelper
       else
         type = identification_type(line)
         line_code = build_line_anchor(diff, line_new, line_old)
-        yield(full_line, type, line_code, line_new, line_old)
+        yield(full_line, type, line_code, line_new, line_old, raw_line)
       end
 
 

app/models/note.rb

@@ -99,10 +99,21 @@ class Note < ActiveRecord::Base
     diff.new_path if diff
   end
 
+  def diff_old_line
+    line_code.split('_')[1].to_i
+  end
+
   def diff_new_line
     line_code.split('_')[2].to_i
   end
 
+  def diff_line
+    if diff
+      @diff_line ||= diff.diff.lines.select { |line| line =~ /\A\+/ }[diff_new_line] ||
+        diff.diff.lines.select { |line| line =~ /\A\-/ }[diff_old_line]
+    end
+  end
+
   def discussion_id
     @discussion_id ||= [:discussion, noteable_type.try(:underscore), noteable_id || commit_id, line_code].join("-").to_sym
   end

app/views/projects/commits/_text_file.html.haml

@@ -3,7 +3,7 @@
   %a.supp_diff_link Diff suppressed. Click to show
 
 %table.text-file{class: "#{'hide' if too_big}"}
-  - each_diff_line(diff, index) do |line, type, line_code, line_new, line_old|
+  - each_diff_line(diff, index) do |line, type, line_code, line_new, line_old, raw_line|
     %tr.line_holder{ id: line_code, class: "#{type}" }
       - if type == "match"
         %td.old_line= "..."
@@ -20,4 +20,4 @@
     - if @reply_allowed
       - comments = @line_notes.select { |n| n.line_code == line_code }.sort_by(&:created_at)
       - unless comments.empty?
-        = render "projects/notes/diff_notes_with_reply", notes: comments
+        = render "projects/notes/diff_notes_with_reply", notes: comments, raw_line: raw_line

app/views/projects/notes/_diff_notes_with_reply.html.haml

 - note = notes.first # example note
-%tr.notes_holder
+-# Check if line want not changed since comment was left
+- if !defined?(raw_line) || raw_line == note.diff_line
+  %tr.notes_holder
     %td.notes_line{ colspan: 2 }
       %span.btn.disabled
         %i.icon-comment