Wiki: Vim Diff

The MyDiff() function that comes with the standard vim installation (as of 6.4) does not handle diffs very well (or indeed at all). Here is an example of a MyDiff() function that works perfectly well.

if has('win32')
  set diffexpr=MyDiff()
  function! MyDiff()
    let opt = '-a --binary '
    if &diffopt =~ 'icase' | let opt = opt . '-i ' | endif
    if &diffopt =~ 'iwhite' | let opt = opt . '-b ' | endif
    let arg1 = v:fname_in
    if arg1 =~ ' ' | let arg1 = '"' . arg1 . '"' | endif
    let arg2 = v:fname_new
    if arg2 =~ ' ' | let arg2 = '"' . arg2 . '"' | endif
    let arg3 = v:fname_out
    if arg3 =~ ' ' | let arg3 = '"' . arg3 . '"' | endif
    if &sh =~ '\<cmd'
      silent execute '!""' . $VIM. '\vim64\diff.exe" ' . opt . arg1 . ' ' . arg2 . ' > ' . arg3 . '"'
    else
      silent execute '!'.$VIM.'\vim64\diff.exe" ' . opt . arg1 . ' ' . arg2 . ' > ' . arg3
    endif
  endfunction
endif