This is an enhanced version of the snippet provided under :help diff-original-file.
Where the original :DiffOrig only shows differences between the buffer in memory and the file on disk, :Diff can be used in two ways:
against the file on disk, like the original, with:
:Diff
against an arbitrary Git revision of the current file, with:
:Diff HEAD
Adapted from here by checking for git dir and executable.
| function! Diff(mods, spec) abort | |
| let mods = a:mods | |
| if !len(mods) && &diffopt =~# 'vertical' | |
| let mods = 'vertical' | |
| endif | |
| let cmd = '++edit #' | |
| if len(a:spec) | |
| let gitdir = finddir('.git', '.;') | |
| if empty(gitdir) | |
| echoerr 'no git dir found!' | |
| return 1 | |
| else | |
| if !executable('git') | |
| echoerr 'no git executable found!' | |
| return 1 | |
| else | |
| let cmd = "!git -C " . shellescape(fnamemodify(gitdir, ':p:h:h')) . " show " . a:spec . ":#" | |
| endif | |
| endif | |
| endif | |
| execute mods . ' new' | |
| setlocal bufhidden=wipe buftype=nofile nobuflisted noswapfile | |
| execute "read " . cmd | |
| silent 0d_ | |
| let &filetype = getbufvar('#', '&filetype') | |
| augroup Diff | |
| autocmd! * <buffer> | |
| autocmd BufWipeout <buffer> diffoff! | |
| augroup END | |
| diffthis | |
| wincmd p | |
| diffthis | |
| endfunction | |
| command! -nargs=? Diff call Diff(<q-mods>, <q-args>) |