Re: project.el and merging multiple projects into one?

[Eli Zaretskii]

> From: "Alfred M. Szmidt" <ams@gnu.org>
> Date: Fri, 29 Apr 2022 11:52:32 -0400
> Cc: emacs-devel@gnu.org
> 
>    Otherwise, it depends on how the sub-projects are structured. Which 
>    project backend is responsible for them, for instance.
> 
> What is that?

Invoke this:

  M-: (project-current nil DIRECTORY) RET

where DIRECTORY is the root of the tree of the
sub-module/sub-project.  The value that the above returns should tell
you the backend for DIRECTORY.  It could be nil, meaning that Emacs
didn't find any backend for that directory.