How to prevent Vim from loading a specific system-wide ftplugin?

Question

I'm writing a custom ftplugin for handling systemd file type. I've copied parts of code from vim's own systemd ftplugin and now the latter conflicts with my own code:

Error detected while processing BufRead Autocommands for "*/etc/systemd/*.conf"..FileType Autocommands for "*"..function <SNR>1
4_LoadFTPlugin[18]..script /usr/share/vim/vim90/ftplugin/systemd.vim:
line   12:
E174: Command already exists: add ! to replace it: Sman silent exe '!' . KeywordLookup_systemd(<q-args>) | redraw!

From what I see, the error comes from the system-wide ftplugin. The problem is, it uses the normal b:did_ftplugin guard improperly. Instead of this:

if exists("b:did_ftplugin")
  finish
endif
let b:did_ftplugin = 1

...it does this:

if !exists('b:did_ftplugin')
  " some code that sets b:did_ftplugin
endif

" some more code

As such, the code that is not guarded comes into conflict with my own code.

---

I suppose this is something that should be patched upstream, but in the meantime, is there a way to prevent Vim from loading the system-wide ftplugin/systemd.vim and only load mine?

Answer 1

Introduce systemd2

What you could do is selecting another filetype for systemd (e.g. systemd2) by having a ftdetect/systemd2.vim that set it.

~/vimfiles/ftdetect/systemd2.vim

" Systemd unit files
au BufNewFile,BufRead */systemd/*.{automount,dnssd,link,mount,netdev,network,nspawn,path,service,slice,socket,swap,target,timer}    setf systemd2
" Systemd overrides
au BufNewFile,BufRead */etc/systemd/*.conf.d/*.conf setf systemd2
au BufNewFile,BufRead */etc/systemd/system/*.d/*.conf   setf systemd2
au BufNewFile,BufRead */.config/systemd/user/*.d/*.conf setf systemd2
" Systemd temp files
au BufNewFile,BufRead */etc/systemd/system/*.d/.#*  setf systemd2
au BufNewFile,BufRead */etc/systemd/system/.#*      setf systemd2
au BufNewFile,BufRead */.config/systemd/user/*.d/.#*    setf systemd2
au BufNewFile,BufRead */.config/systemd/user/.#*    setf systemd2

The ftplugin/systemd.vim and friends ($VIMRUNTIME/indent/systemd.vim, $VIMRUNTIME/syntax/systemd.vim, $VIMRUNTIME/compiler/systemd.vim) will not be executed anymore and you can put your code in ~/vimfiles/ftplugin/systemd2.vim and friends.

Amend the standard solution

Another solution is to amend the systemd standard solution by moving part your code in ~/vimfiles/after/ftplugin/systemd.vim and make use of the command! to override the Sman command if you need to change it.

Answer 2

This is fixed in a recent runtime commit. If you can run recent versions, you should be able to get the upstream change and continue as usual.