Re: feature/package+vc 04c4c578c7 3/4: Allow for packages to be installed directly from VCS

[Eli Zaretskii <eliz@gnu.org>]

> From: Philip Kaludercic <philipk@posteo.net>
> Cc: emacs-devel@gnu.org
> Date: Sat, 15 Oct 2022 15:52:28 +0000
> 
> Philip Kaludercic <philipk@posteo.net> writes:
> 
> > - The ability to update a package using `package-upgrade'[0]
> 
> [...]
> 
> > [0] This feature is currently broken because it tries to use `vc-pull'
> >     which refuses to work if any changes have been made.  This is an
> >     issue as package-vc-fetch tries to modify the list of ignored files
> >     in a repository (think of .gitignore).  It will either be necessary
> >     to change how vc-pull works or try to do something with
> >     vc-log-incoming + vc-merge.
> 
> Does anyone know if it is possible to do this?

Where is the code which fails vc-pull if there are changes in the
working tree?  is it specific to some backend, perhaps?  The doc
string says:

  On a non-distributed version control system, update the current
  fileset to the tip revisions.  For each unchanged and unlocked
  file, this simply replaces the work file with the latest revision
  on its branch.  If the file contains changes, any changes in the
  tip revision are merged into the working file.

Note that last sentence.  So this ought to work, and if it doesn't,
it's a bug, I guess?

From the shell prompt, "git pull" will fail if the changes are in the
same file as one of those whose changes are brought in by the pull,
but either using --rebase or maybe the stash/pull/unstash dance should
take care of that, I guess?

Or am I missing something?