Re: project.el: git submodules?

[Dmitry Gutov <dgutov@yandex.ru>]

On 12.05.2020 23:45, Michael Welsh Duggan wrote:
> Stefan Monnier<monnier@iro.umontreal.ca>  writes:
> 
>>> FWIW, the examples of git worktrees on my machine all include a ".git/"
>>> directory.  It's just that some of its contents are symbolic links.
>> Hmm... are you sure these are Git worktrees?
>> Maybe they're "poor man's git-worktrees" created by the old
>> `git-new-workdir` hack which has been made obsolete by the "new" `git
>> worktree` feature.
> Pretty sure.
> 
>      /tmp/$ git --version
>      /tmp$ mkdir git-test
>      /tmp$ cd git-test
>      /tmp/git-test$ mkdir repo
>      /tmp/git-test$ cd repo
>      /tmp/git-test/repo$ git init
>      Initialized empty Git repository in/tmp/git-test/repo/.git/
>      /tmp/git-test/repo$ echo "Test file" > repo
>      /tmp/git-test/repo$ git add repo
>      /tmp/git-test/repo$ git commit -m "Initial commit."
>      [master (root-commit) 544fba2] Initial commit.
>       1 file changed, 1 insertion(+)
>       create mode 100644 repo
>      /tmp/git-test/repo$ git worktree add ../worktree
>      Preparing worktree (new branch 'worktree')
>      HEAD is now at 544fba2 Initial commit.
>      /tmp/git-test/repo$ cd ../worktree/
>      /tmp/git-test/worktree$ ls -la .git
>      -rw-r--r-- 1 md5i md5i 51 May 12 16:42 .git
>      /tmp/git-test/worktree$ cat .git
>      gitdir:/tmp/git-test/repo/.git/worktrees/worktree

Perhaps you could suggest an additional test to determine whether a 
directory is a submodule, then?

The contents of '.git' there are fairly similar:

gitdir: ../../.git/modules/site-lisp/company

I guess we could look inside and see whether '.git/modules/' is a 
substring. Detecting a project over Tramp will become a little bit 
slower as a result, though.