Get User "Desktop" well-known folder pathname in Vim (script)

gistfile1.vim

let g:WinUserProfile = ''
try
    let g:WinUserProfile = substitute(system('cygpath -am -C UTF8 -D'), '[[:cntrl:]]', '', 'g')
 catch @^Vim\%((\a\+)\)\=:E\d\+@      " catch any error number
  " Seeing E484: Can't open file /tmp/vWlY1IE/0  # for line 99 (is it because SHELL been messed w/?)   
    call confirm(
      \  printf(
  \ "%s: Could not system() to get WinUserProfile using cygpath under shell \"%s\": %s\n",
  \ s:this_vimfile, &shell, v:exception), 'Ok', 'Ok', 'Warning')
endtry

if g:WinUserProfile != ''
    let g:WinUserProfile = substitute(g:WinUserProfile, '\c/Desktop', '', '')
    if !isdirectory(g:WinUserProfile)
        call confirm(
            \  printf('WARNING: dir for WinUserProfile does not exist: %s worked out "%s",
               \ s:this_vimfile, g:WinUserProfile) ."\n", 'Ok', 'Ok', 'Warning')
        finish
    endi
else
    call confirm('ERROR (critical): Cannot create WinUserProfile string', 'Ok', 'Ok', 'Warning')
endi