Re: project.el: git submodules?

[Dmitry Gutov]

On 14.05.2020 23:13, Dmitry Gutov wrote:
> On 14.05.2020 23:01, Stefan Monnier wrote:
> > +                                    (or
> > +                                     (let ((default-directory parent))
> > +                                       (vc-root-dir))
> > +                                     root)))))
> >
> > I'm not familiar enough with this code to understand what it does: which
> > part tests "is it a submodule"?
> The removed part.
>
> > Or alternatively, which part compares
> > the location of the two repositories?
> The part quoted above. If the parent directory of the root of the 
> current Git worktree belongs to a VC worktree (vc-root-dir returns 
> non-nil), use that worktree's root. Otherwise, use the root of the 
> current repo.
Ah. After re-reading your initial message, I think I understand it 
better. But to compare, we'd need to read the contents of both .git 
files/directories, right?
That, um, sounds more complex than the current solution. And more file 
reads = worse performance over Tramp, so it's not just implementation 
difficulty.
Regarding the particulars, I suppose if .git is a file, and it starts with

gitdir: ../../.git/

where the number of "../" is two or more, then the current dir is 
probably a submodule.