GNU bug report logs - #75983
project crash, file-name-directory "~", file-equal-p nil

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

From: Ship Mints <shipmints <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: project crash, file-name-directory "~", file-equal-p nil
Date: Fri, 31 Jan 2025 19:10:47 -0500

[Message part 1 (text/plain, inline)]

The behaviors below can be seen on 29, 30, 31 (I don't have an earlier
Emacs to test but these issues probably are long-standing). Let's discuss
these as I suspect there may be historical reasons for these behaviors that
I'm unaware of, or maybe these are legitimate, even if old. It's also
possible that I'm misunderstanding something.

Issue 1:

(file-name-directory "~") ; returns nil but I think this should return "~/":
(file-name-directory
  (abbreviate-file-name "/home/username")) ; same
(file-name-directory
  (abbreviate-file-name "/Users/username")) ; for all us macOS users

Issue 2:

I think file-equal-p should accept nil and consider it unspecified as in
its docstring: "If FILE1 or FILE2 does not exist, the return value is
unspecified."

And/or find-file-name-handler should accept nil and then return nil.

(file-equal-p "~" "~") ; t
(file-equal-p "~" "/home/username") ; t
(file-equal-p "~" (file-name-directory "~")) ; boom
;; (wrong-type-argument stringp nil)
;; find-file-name-handler(nil file-equal-p)

Issue 3:

project-forget-projects-under crashes when `project-list-file' contains
"/home/username", which appears in my remembered project list.

(defun project--read-project-list ()
...
   (abbreviate-file-name name) ; converts "/home/username" to "~"

(defun project-forget-projects-under ()
...
      (dolist (proj (project-known-project-roots))
        (when (file-equal-p (file-name-directory proj) dir) ; <--- boom on
nil

I'm happy to submit patches for any or all of these including guarding
project-forget-projects-under to check for nil and/or amending
project--read-project-list to convert "~" to "~/" as workarounds, with each
submitted against a discrete bug number.

-Stephane

[Message part 2 (text/html, inline)]

Message #8 received at 75983 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Ship Mints <shipmints <at> gmail.com>,
 Dmitry Gutov <dmitry <at> gutov.dev>
Cc: 75983 <at> debbugs.gnu.org
Subject: Re: bug#75983: project crash, file-name-directory "~",
 file-equal-p nil
Date: Sat, 01 Feb 2025 10:50:21 +0200

> From: Ship Mints <shipmints <at> gmail.com>
> Date: Fri, 31 Jan 2025 19:10:47 -0500
> 
> The behaviors below can be seen on 29, 30, 31 (I don't have an earlier Emacs to test but these issues
> probably are long-standing). Let's discuss these as I suspect there may be historical reasons for these
> behaviors that I'm unaware of, or maybe these are legitimate, even if old. It's also possible that I'm
> misunderstanding something.

Thanks, but please don't mix separate issues in the same bug report.
If you think file-name-directory has a bug (I disagree), please report
a separate bug against file-name-directory.  If you think file-equal-p
should accept nil as its argument (I'm not sure I will agree, but
maybe you will convince), please report a separate feature-request bug
about that function.

> Issue 3:
> 
> project-forget-projects-under crashes when `project-list-file' contains "/home/username", which appears in
> my remembered project list.

It doesn't crash, it signals an error.  Crashing means the entire
Emacs session goes down in flames.

> (defun project--read-project-list ()
> ...
>    (abbreviate-file-name name) ; converts "/home/username" to "~"
> 
> (defun project-forget-projects-under ()
> ...
>       (dolist (proj (project-known-project-roots))
>         (when (file-equal-p (file-name-directory proj) dir) ; <--- boom on nil
> 
> I'm happy to submit patches for any or all of these including guarding project-forget-projects-under to check
> for nil and/or amending project--read-project-list to convert "~" to "~/" as workarounds, with each submitted
> against a discrete bug number.

I think this should be solved in project.el, but let's hear what
Dmitry (CC'ed) thinks.

Message #11 received at 75983 <at> debbugs.gnu.org (full text, mbox):

From: Ship Mints <shipmints <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: Dmitry Gutov <dmitry <at> gutov.dev>, 75983 <at> debbugs.gnu.org
Subject: Re: bug#75983: project error with file-name-directory "~" returning
 nil
Date: Sat, 1 Feb 2025 06:04:21 -0500

[Message part 1 (text/plain, inline)]

Separate bugs reports for sure, Eli, but I first thought it useful to
discuss holistically to illustrate. Let's consider this bug report to be
solely about project.

Dmitry, I think the following patch to project--write-project-list might
suffice to avoid this in the future:

diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
index f2a27ff91dd..f9b3b8891bc 100644
--- a/lisp/progmodes/project.el
+++ b/lisp/progmodes/project.el
@@ -1824,7 +1824,7 @@ project--read-project-list
                (lambda (elem)
                  (let ((name (car elem)))
                    (list (if (file-remote-p name) name
-                           (abbreviate-file-name name)))))
+                           (file-name-as-directory (abbreviate-file-name
name))))))
                (condition-case nil
                    (read (current-buffer))
                  (end-of-file

This causes /Users/xxx to appear as /Users/xxx/ in the project file and
then project--read-project-list produces ~/ rather than ~ for which
file-name-directory produces nil.

(defun project--read-project-list ()
...
                           (file-name-as-directory (abbreviate-file-name
name))))))

Note: I did not consider the tramp/remote file cases in this analysis.

On Sat, Feb 1, 2025 at 3:50 AM Eli Zaretskii <eliz <at> gnu.org> wrote:

> > From: Ship Mints <shipmints <at> gmail.com>
> > Date: Fri, 31 Jan 2025 19:10:47 -0500
> >
> > The behaviors below can be seen on 29, 30, 31 (I don't have an earlier
> Emacs to test but these issues
> > probably are long-standing). Let's discuss these as I suspect there may
> be historical reasons for these
> > behaviors that I'm unaware of, or maybe these are legitimate, even if
> old. It's also possible that I'm
> > misunderstanding something.
>
> Thanks, but please don't mix separate issues in the same bug report.
> If you think file-name-directory has a bug (I disagree), please report
> a separate bug against file-name-directory.  If you think file-equal-p
> should accept nil as its argument (I'm not sure I will agree, but
> maybe you will convince), please report a separate feature-request bug
> about that function.
>
> > Issue 3:
> >
> > project-forget-projects-under crashes when `project-list-file' contains
> "/home/username", which appears in
> > my remembered project list.
>
> It doesn't crash, it signals an error.  Crashing means the entire
> Emacs session goes down in flames.
>
> > (defun project--read-project-list ()
> > ...
> >    (abbreviate-file-name name) ; converts "/home/username" to "~"
> >
> > (defun project-forget-projects-under ()
> > ...
> >       (dolist (proj (project-known-project-roots))
> >         (when (file-equal-p (file-name-directory proj) dir) ; <--- boom
> on nil
> >
> > I'm happy to submit patches for any or all of these including guarding
> project-forget-projects-under to check
> > for nil and/or amending project--read-project-list to convert "~" to
> "~/" as workarounds, with each submitted
> > against a discrete bug number.
>
> I think this should be solved in project.el, but let's hear what
> Dmitry (CC'ed) thinks.
>

[Message part 2 (text/html, inline)]

Message #14 received at 75983 <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dmitry <at> gutov.dev>
To: Ship Mints <shipmints <at> gmail.com>, Eli Zaretskii <eliz <at> gnu.org>
Cc: 75983 <at> debbugs.gnu.org
Subject: Re: bug#75983: project error with file-name-directory "~" returning
 nil
Date: Wed, 12 Feb 2025 04:49:46 +0200

Hi!

On 01/02/2025 13:04, Ship Mints wrote:
> Dmitry, I think the following patch to project--write-project-list might 
> suffice to avoid this in the future:
> 
> diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
> index f2a27ff91dd..f9b3b8891bc 100644
> --- a/lisp/progmodes/project.el
> +++ b/lisp/progmodes/project.el
> @@ -1824,7 +1824,7 @@ project--read-project-list
>                  (lambda (elem)
>                    (let ((name (car elem)))
>                      (list (if (file-remote-p name) name
> -                           (abbreviate-file-name name)))))
> +                           (file-name-as-directory (abbreviate-file- 
> name name))))))
>                  (condition-case nil
>                      (read (current-buffer))
>                    (end-of-file

Yeah, this is a decent solution, thanks.

Any idea though, how an entry without a trailing "/" got into that file? 
Written by some older version of project.el?

Message #17 received at 75983 <at> debbugs.gnu.org (full text, mbox):

From: Ship Mints <shipmints <at> gmail.com>
To: Dmitry Gutov <dmitry <at> gutov.dev>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 75983 <at> debbugs.gnu.org
Subject: Re: bug#75983: project error with file-name-directory "~" returning
 nil
Date: Wed, 12 Feb 2025 05:10:59 -0500

[Message part 1 (text/plain, inline)]

I don't know. Could have been from an older project, yes.

On Tue, Feb 11, 2025 at 9:49 PM Dmitry Gutov <dmitry <at> gutov.dev> wrote:

> Hi!
>
> On 01/02/2025 13:04, Ship Mints wrote:
> > Dmitry, I think the following patch to project--write-project-list might
> > suffice to avoid this in the future:
> >
> > diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
> > index f2a27ff91dd..f9b3b8891bc 100644
> > --- a/lisp/progmodes/project.el
> > +++ b/lisp/progmodes/project.el
> > @@ -1824,7 +1824,7 @@ project--read-project-list
> >                  (lambda (elem)
> >                    (let ((name (car elem)))
> >                      (list (if (file-remote-p name) name
> > -                           (abbreviate-file-name name)))))
> > +                           (file-name-as-directory (abbreviate-file-
> > name name))))))
> >                  (condition-case nil
> >                      (read (current-buffer))
> >                    (end-of-file
>
> Yeah, this is a decent solution, thanks.
>
> Any idea though, how an entry without a trailing "/" got into that file?
> Written by some older version of project.el?
>

[Message part 2 (text/html, inline)]

Message #22 received at 75983-done <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dmitry <at> gutov.dev>
To: Ship Mints <shipmints <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 75983-done <at> debbugs.gnu.org
Subject: Re: bug#75983: project error with file-name-directory "~" returning
 nil
Date: Wed, 12 Feb 2025 18:06:57 +0200

On 12/02/2025 12:10, Ship Mints wrote:
> I don't know. Could have been from an older project, yes.

All right. Well, no problem adding the conversion to account for similar 
cases. Pushed to master as 2bb38cc46dfedfb1, closing.

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