Subject: Re: bug#58525: 28.1: `vc-dir' (key sequence: C-x v d) fails when used with a CVS repository

From: Dmitry Gutov <[email-masked]>
Date: Mon, 17 Oct 2022 16:00:25 +0300

On 17.10.2022 09:06, Eli Zaretskii wrote:
> AFAIK, the VC's support for CVS is based on detecting the CVS
> subdirectory of a directory where you invoke vc-dir.  If that
> subdirectory is not found, VC will assume the backend is not CVS.  In
> which case your assumptions seem to be mistaken.
> 
> But I will let VC expert to chime in here, because I may be wrong or
> confused.

Here's the basic logic:

(defun vc-cvs-registered (f)
   "Return non-nil if file F is registered with CVS."
   (when (file-readable-p (expand-file-name
			  "CVS/Entries" (file-name-directory f)))
     ...