$MYVIMDIR unset when no ~/.vimrc (netrw creating '$MYVIMDIR' directories)

[sandwm]

Steps to reproduce

1. Make sure you don't have a .vimrc, e.g.: mv ~/.vimrc{,.bak}
2. Run vim . (or just vim and go to 4.)
3. See a new directory named '$MYVIMDIR' (see note on netrw.vim below)
4. See $MYVIMDIR is not set: :echo expand("$MYVIMDIR")

When ~/.vimrc exists, no directory $MYVIMDIR is created and the environment variable is set to /home/swm/.vim/ (in my case; first directory in runtimepath).

Expected behaviour

$MYVIMDIR is set (regardless of a user .vimrc existing or not), as starting.txt documentation seems to imply:

The $MYVIMRC or $MYGVIMRC environment variable will be set to the first found
vimrc and/or gvimrc file while $MYVIMDIR is set to the users personal runtime
directory 'rtp' (typically the first entry in 'runtimepath').
Note: These environment variables resolve symbolic links, but 'rtp' does not.

starting.txt also says:

If Vim was started with "-u filename", the file "filename" is used.
All following initializations until 4. are skipped. $MYVIMRC and
$MYVIMDIR are not set.
"vim -u NORC" can be used to skip these initializations without
reading a file. "vim -u NONE" also skips loading plugins. |-u|

So with vim -u ... $MYVIMDIR is not set (as per documentation), but this also happens when running just vim and no user .vimrc exists. That's arguably a similar situation, but not documented as such.

In the source, $MYVIMDIR is set in src/option.c, vimrc_found().

I ask to either

• set $MYVIMDIR even without .vimrc, or
• make the documentation more clear.

Resulting netrw issue

When you don't have a .vimrc and look into any directory using netrw.vim, it will create a '$MYVIMDIR' directory in the current working directory (not necessarily the directory you look at).

That's how I stumbled over this: There were some of these directories lying around. On some users / hosts they were created when using vim, on others not. Turned out, the difference was the (non-)existence of a user .vimrc.

netrw.vim uses $MYVIMRC in runtime/pack/dist/opt/netrw/autoload/netrw.vim:

" ---------------------------------------------------------------------
"  s:NetrwHome: this function determines a "home" for saving bookmarks and history {{{2
function! s:NetrwHome()
  if has('nvim')
    let home = netrw#own#JoinPath(stdpath('state'), 'netrw')
  elseif exists("g:netrw_home")
    let home = expand(g:netrw_home)
  else
    let home = expand("$MYVIMDIR")->substitute("/$", "", "")
  endif
  [...]

I can create an issue at https://github.com/saccarosium/netrw.vim depending on whether you consider this a vim or a netrw bug.

Version of Vim

9.1.1065 (Huge version without GUI. Arch package)

Environment

OS: Arch Linux
Terminal: mate-terminal
$TERM: xterm-256color
Shell: bash

Logs and stack traces

[sandwm]

This seems to be the commit that introduced $MYVIMDIR to netrw: saccarosium/netrw.vim@092e636

[chrisbra]

Well, if you don't have a ~/.vim/ directory, what should $MYVIMDIR point to? (I am assuming you don't have ~/.vim/, because I have one and no ~/.vimrc file and $MYVIMDIR works for me.

for the netrw related thing, ping @saccarosium

[sandwm]

~/.vim/ exists:

$ ls ~/.vim/
spell
$ vim
# inside vim:
:echo expand("$MYVIMDIR")
$MYVIMDIR
:set rtp?
  runtimepath=~/.vim,/usr/share/vim/vimfiles,/usr/share/vim/vim91,/usr/share/vim/vim91/pack/dist/opt/netrw,/usr/share/vim/vim91/pack/dist/opt/matchit,/usr/share/vim/vimfiles/after,~/.vim/after

Similar situation on a different host, where /root/.vim/ contains only .netrwhist. $MYVIMDIR is not set by vim. On that host, vim configuration is entirely unmodified, i.e. just what Arch packages: /etc/vimrc, archlinux.vim in system runtimepath.

I also tested with an almost empty /etc/vimrc (and no ~/.vimrc) to see if that would change something:

$ cat /etc/vimrc
if &compatible
  set nocompatible
endif

Still same situation.

[sandwm]

I am assuming you don't have ~/.vim/, because I have one and no ~/.vimrc file and $MYVIMDIR works for me.

@chrisbra Do you have any other user vimrc file, as mentioned here in starting.txt? I assume vimrc_found() will be called for those. I'll try to check that later.

[chrisbra]

@chrisbra Do you have any other user vimrc file, as mentioned here in starting.txt? I assume vimrc_found() will be called for those. I'll try to check that later.

Yes of course, my default ~/.vim/vimrc file.

[sandwm]

$MYVIMDIR is set by vimrc_found(), which is called ...

• as vimrc_found(NULL, NULL); by process_env() for $VIMINIT. That won't set $MYVIMDIR because it won't go into if (fname != NULL).
• by do_source_ext() (depending on the is_vimrc parameter), which is documented as: 'Read the file "fname" and execute its lines as EX commands.'
  • source_startup_scripts() calls do_source() -> do_source_ext() with is_vimrc = DOSO_VIMRC for what should be the files documented in starting.txt (i.e., ~/.vimrc, ~/.vim/vimrc, $XDG_CONFIG_HOME/vim/vimrc on Unix). (Also applies to .vimrc from current directory if exrc is set.)
  • gui_init() does the same with gvimrc files and is_vimrc = DOSO_GVIMRC.

So that's the implemented and observed behaviour: $MYVIMDIR is only set if a user vimrc file exists. So, the question is: is that the intended behaviour?
a) If it's intended, I'll create a pull request to make this more clear in the documentation. netrw will also need a fix in that case.
b) If it's not intended, vim code needs a fix.

@chrisbra, since you're the current maintainer and #15576 is yours, too, that's for you to decide. I'm leaning more towards b), since the vim directory (~/.vim/ or whatever) is useful even without a vimrc, but I haven't written much vim plugin code or similar.

[saccarosium]

I will push a fix.

Sorry for the late responce.

IMHO vim should set MYVIMDIR by default to .vim.

[sandwm]

Thanks for fixing netrw!

However, I'm a bit confused that this vim issue is closed. I would have expected either a documentation or a code fix in vim before that (see my comment above). Otherwise I would expect similar issues to occur in the future with other plugins that depend on $MYVIMDIR (because they assume vim to set it). I can clarify the documentation or I could try my hand at patching vim to set $MYVIMDIR regardless of a user vimrc existing. But I don't know what is the desired behaviour.

[chrisbra]

This should still be fixed on the Vim side. Feel free to have a look at it