{
  output.extraConfig = ''
    " Highlight trailing whitespace
    " https://idie.ru/posts/vim-modern-cpp
    highlight ExtraWhitespace ctermbg=red guibg=red
    match ExtraWhitespace /\s\+$/
    au BufWinEnter * match ExtraWhitespace /\s\+$/
    au InsertEnter * match ExtraWhitespace /\s\+\%#\@<!$/
    au InsertLeave * match ExtraWhitespace /\s\+$/
    au BufWinLeave * call clearmatches()
  '';
}