GNU bug report logs - #57418
28.1; Projects not saved when vc-handled-backends is nil

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 28.1; Projects not saved when vc-handled-backends is nil
Date: Thu, 25 Aug 2022 20:35:55 +0000

Good day,

I've recently been migrating from projectile to the built-in
project.el. Since then, one major annoyance is that the projects are
never saved into project-list-file, so I have to re-enter the projects'
paths everytime I make a query.

I have narrowed it down to vc-handled-backends being set to nil in my
init-file. If it's left at its default, it works as expected. I could
just leave the variable at its default but (iirc) it's part of a bunch
of optimizations I made to speedup my TRAMP setup, so I'm reluctant to
do that.  And just to be perfectly clear, the rest of project mode seemingly
works as expected if that variable is nil, it's just the projects are
not saved.

Steps to reproduce from emacs -Q:

+ (setq 'vc-handled-backends nil)

+ Use project.el to find a file in any project not in your
project-list-file, e.g. with C-x p p

+ Open your project-list-file, "/.emacs.d/projects" in my case

Expected result: The recently opened project is listed
Actual result: The recently opened project is *not* listed

Thanks in advance,
L-G


In GNU Emacs 28.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.33,
cairo version 1.17.6)
  of 2022-04-27 built on frederik
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Arch Linux

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Message #8 received at 57418 <at> debbugs.gnu.org (full text, mbox):

From: Philip Kaludercic <philipk <at> posteo.net>
To: Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com>
Cc: 57418 <at> debbugs.gnu.org
Subject: Re: bug#57418: 28.1; Projects not saved when vc-handled-backends is
 nil
Date: Fri, 26 Aug 2022 07:46:06 +0000

Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com> writes:

>
> Good day,
>
> I've recently been migrating from projectile to the built-in
> project.el. Since then, one major annoyance is that the projects are
> never saved into project-list-file, so I have to re-enter the projects'
> paths everytime I make a query.
>
> I have narrowed it down to vc-handled-backends being set to nil in my
> init-file. If it's left at its default, it works as expected. I could
> just leave the variable at its default but (iirc) it's part of a bunch
> of optimizations I made to speedup my TRAMP setup, so I'm reluctant to
> do that.  And just to be perfectly clear, the rest of project mode seemingly
> works as expected if that variable is nil, it's just the projects are
> not saved.
>
> Steps to reproduce from emacs -Q:
>
> + (setq 'vc-handled-backends nil)
>
> + Use project.el to find a file in any project not in your
> project-list-file, e.g. with C-x p p
>
> + Open your project-list-file, "/.emacs.d/projects" in my case
>
> Expected result: The recently opened project is listed
> Actual result: The recently opened project is *not* listed

This is to be expected, as by default `project-find-functions' only
includes one function that uses and relies on VC.  If it were just this,
I would therefore not consider this to be a bug.  Does anything else
work?  `project-find-file', `project-shell', `project-compile', ...?

What might be worth doing is issuing a warning if `project-try-vc' (the
default project-finding-function) is invoked while VC is effectively
disabled.

You could try solving this by either adding your own alternative to
`project-try-vc' (e.g. if you just use Git, then this

--8<---------------cut here---------------start------------->8---
(defun project-try-git (dir)
  "Find a super-directory of DIR containing a root file."
  (let ((repo (locate-dominating-file dir ".git")))
    (and repo (list 'git dir))))

(cl-defmethod project-root ((project (head git)))
  "Return the root of a explicit PROJECT."
  (cadr project ))

(with-eval-after-load 'project
  (add-hook 'project-find-functions #'project-try-git))
--8<---------------cut here---------------end--------------->8---

might be enough, but still be optimised a bit more).

Another idea might be to just disable VC for Tramp, or rather just some
Tramp connections? 

> Thanks in advance,
> L-G

Message #13 received at 57418 <at> debbugs.gnu.org (full text, mbox):

From: Michael Albinus <michael.albinus <at> gmx.de>
To: Philip Kaludercic <philipk <at> posteo.net>
Cc: 57418 <at> debbugs.gnu.org, Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com>
Subject: Re: bug#57418: 28.1; Projects not saved when vc-handled-backends is
 nil
Date: Fri, 26 Aug 2022 16:09:37 +0200

Philip Kaludercic <philipk <at> posteo.net> writes:

Hi,

> Another idea might be to just disable VC for Tramp, or rather just some
> Tramp connections?

Yes, this shall be possible via connection-local variables (I haven't
tested, 'tho).

>> Thanks in advance,
>> L-G

Best regards, Michael.

Message #16 received at 57418 <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: Philip Kaludercic <philipk <at> posteo.net>,
 Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com>
Cc: 57418 <at> debbugs.gnu.org
Subject: Re: bug#57418: 28.1; Projects not saved when vc-handled-backends is
 nil
Date: Fri, 26 Aug 2022 17:21:13 +0300

On 26.08.2022 10:46, Philip Kaludercic wrote:
> Louis-Guillaume Gagnon<gagnonlg <at> protonmail.com>  writes:
> 
>> Good day,
>>
>> I've recently been migrating from projectile to the built-in
>> project.el. Since then, one major annoyance is that the projects are
>> never saved into project-list-file, so I have to re-enter the projects'
>> paths everytime I make a query.
>>
>> I have narrowed it down to vc-handled-backends being set to nil in my
>> init-file. If it's left at its default, it works as expected. I could
>> just leave the variable at its default but (iirc) it's part of a bunch
>> of optimizations I made to speedup my TRAMP setup, so I'm reluctant to
>> do that.  And just to be perfectly clear, the rest of project mode seemingly
>> works as expected if that variable is nil, it's just the projects are
>> not saved.
>>
>> Steps to reproduce from emacs -Q:
>>
>> + (setq 'vc-handled-backends nil)
>>
>> + Use project.el to find a file in any project not in your
>> project-list-file, e.g. with C-x p p
>>
>> + Open your project-list-file, "/.emacs.d/projects" in my case
>>
>> Expected result: The recently opened project is listed
>> Actual result: The recently opened project is*not*  listed
> This is to be expected, as by default `project-find-functions' only
> includes one function that uses and relies on VC.  If it were just this,
> I would therefore not consider this to be a bug.  Does anything else
> work?  `project-find-file', `project-shell', `project-compile', ...?

I'm honestly surprised that things work with vc-handled-backends disabled.

Louis-Guillaume, does (project-current) ever evaluate to non-nil on your 
system? I'm guessing you end up picking the project directory manually 
every time.

> What might be worth doing is issuing a warning if `project-try-vc' (the
> default project-finding-function) is invoked while VC is effectively
> disabled.

Probably not: after all, the user can have some next backend configured. 
And we allow setting vc-handled-backends to nil.

> You could try solving this by either adding your own alternative to
> `project-try-vc' (e.g. if you just use Git, then this
> 
> --8<---------------cut here---------------start------------->8---
> (defun project-try-git (dir)
>    "Find a super-directory of DIR containing a root file."
>    (let ((repo (locate-dominating-file dir ".git")))
>      (and repo (list 'git dir))))
> 
> (cl-defmethod project-root ((project (head git)))
>    "Return the root of a explicit PROJECT."
>    (cadr project ))
> 
> (with-eval-after-load 'project
>    (add-hook 'project-find-functions #'project-try-git))
> --8<---------------cut here---------------end--------------->8---
> 
> might be enough, but still be optimised a bit more).

This should work, yes.

We could also add a variable which would substitute vc-handled-backends 
for the purposes of project.el (we'd temporarily use its value). Not 
sure it's worth the added complexity, though.

> Another idea might be to just disable VC for Tramp, or rather just some
> Tramp connections?

(setq-local vc-handled-backends) inside find-file-hook behind a 
file-remote-p check could do the trick.

Message #19 received at 57418 <at> debbugs.gnu.org (full text, mbox):

From: Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com>
To: Dmitry Gutov <dgutov <at> yandex.ru>, Philip Kaludercic <philipk <at> posteo.net>
Cc: 57418 <at> debbugs.gnu.org
Subject: Re: bug#57418: 28.1;
 Projects not saved when vc-handled-backends is nil
Date: Fri, 26 Aug 2022 14:34:54 +0000

Hi Dmitry & all,

Le 8/26/22 à 07:21, Dmitry Gutov a écrit :
>> This is to be expected, as by default `project-find-functions' only
>> includes one function that uses and relies on VC.  If it were just this,
>> I would therefore not consider this to be a bug.  Does anything else
>> work?  `project-find-file', `project-shell', `project-compile', ...?
> I'm honestly surprised that things work with vc-handled-backends disabled.
>
> Louis-Guillaume, does (project-current) ever evaluate to non-nil on your
> system? I'm guessing you end up picking the project directory manually
> every time.

Indeed, it's always nil if vc-handled-backends is also nil. I think the
situation now makes more sense to me now; I thought the only problem is
that the projects are not saved but the reason why I have to reenter the
project every  time is deeper and related to project-root, I guess.

I will explore the various proposed ways to get the equivalent setup
without wholesale disabling vc. Thanks to everyone who chimed in!

L-G

Message #22 received at 57418 <at> debbugs.gnu.org (full text, mbox):

From: Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com>
To: Dmitry Gutov <dgutov <at> yandex.ru>, Philip Kaludercic <philipk <at> posteo.net>
Cc: 57418 <at> debbugs.gnu.org
Subject: Re: bug#57418: 28.1;
 Projects not saved when vc-handled-backends is nil
Date: Fri, 26 Aug 2022 16:11:04 +0000

Dear all,

This appears to do what I want:

   (setq vc-follow-symlinks nil)
   (defun my-vc-off-if-remote ()
     (if (file-remote-p (buffer-file-name))
         (setq-local vc-handled-backends nil)))
   (add-hook 'find-file-hook 'my-vc-off-if-remote)

I guess this can be closed as "notabug".

Thanks!

L-G

Message #27 received at 57418-done <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: Louis-Guillaume Gagnon <gagnonlg <at> protonmail.com>,
 Philip Kaludercic <philipk <at> posteo.net>
Cc: 57418-done <at> debbugs.gnu.org
Subject: Re: bug#57418: 28.1; Projects not saved when vc-handled-backends is
 nil
Date: Sat, 27 Aug 2022 01:36:25 +0300

On 26.08.2022 19:11, Louis-Guillaume Gagnon wrote:
> Dear all,
> 
> This appears to do what I want:
> 
>     (setq vc-follow-symlinks nil)
>     (defun my-vc-off-if-remote ()
>       (if (file-remote-p (buffer-file-name))
>           (setq-local vc-handled-backends nil)))
>     (add-hook 'find-file-hook 'my-vc-off-if-remote)
> 
> I guess this can be closed as "notabug".

Very good, closing.

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