bug#18481: vc/vc-git.el: use `with-demoted-errors' instead of `ignore-errors'.

bug#18481: vc/vc-git.el: use `with-demoted-errors' instead of `ignore-errors'.

[Emilio Lopes]

cf. http://lists.gnu.org/archive/html/bug-gnu-emacs/2014-09/msg00394.html

--- lisp/ChangeLog    2014-09-15 00:20:21 +0000
+++ lisp/ChangeLog    2014-09-15 13:36:10 +0000
@@ -1,3 +1,14 @@
+2014-09-15  Emilio C. Lopes  <eclig@gmx.net>
+
+    * vc/vc-git.el (vc-git-registered): use `with-demoted-errors'
+    instead of `ignore-errors' so that the user is informed if
+    something unexpected happens.
+
 2014-09-15  Glenn Morris  <rgm@gnu.org>

     * image.el (image-multi-frame-p): Fix thinko - do not force

=== modified file 'lisp/vc/vc-git.el'
--- lisp/vc/vc-git.el    2014-09-04 16:34:45 +0000
+++ lisp/vc/vc-git.el    2014-09-15 13:36:10 +0000
@@ -185,7 +185,7 @@
                ;; path specs.
                ;; See also: http://marc.info/?l=git&m=125787684318129&w=2
                (name (file-relative-name file dir))
-               (str (ignore-errors
+               (str (with-demoted-errors "Error: %S"
                       (cd dir)
                       (vc-git--out-ok "ls-files" "-c" "-z" "--" name)
                       ;; If result is empty, use ls-tree to check for deleted

bug#18481: vc/vc-git.el: use `with-demoted-errors' instead of `ignore-errors'.

[Lars Ingebrigtsen]

Emilio Lopes <eclig@gmx.net> writes:

> cf. http://lists.gnu.org/archive/html/bug-gnu-emacs/2014-09/msg00394.html
>
> --- lisp/ChangeLog    2014-09-15 00:20:21 +0000
> +++ lisp/ChangeLog    2014-09-15 13:36:10 +0000
> @@ -1,3 +1,14 @@
> +2014-09-15  Emilio C. Lopes  <eclig@gmx.net>
> +
> +    * vc/vc-git.el (vc-git-registered): use `with-demoted-errors'
> +    instead of `ignore-errors' so that the user is informed if
> +    something unexpected happens.

(I'm going through old bug reports that unfortunately have not received
any responses yet.)

So, in that URL Stefan suggested using with-demoted-errors instead of
ignore-errors here, and that seems sensible.  But I'm wondering whether
this code is expected to fail, and whether the errors (in that case) are
totally uninteresting?

I've done some testing (without the `ignore-errors'), and in my tests
the code doesn't fail, so I think the patch suggested makes sense.

Does this patch makes sense to everybody else, too?

(defun vc-git-registered (file)
  "Check whether FILE is registered with git."
  (let ((dir (vc-git-root file)))
    (when dir
      (with-temp-buffer
        (let* (process-file-side-effects
               ;; Do not use the `file-name-directory' here: git-ls-files
               ;; sometimes fails to return the correct status for relative
               ;; path specs.
               ;; See also: http://marc.info/?l=git&m=125787684318129&w=2
               (name (file-relative-name file dir))
               (str (ignore-errors
                      (cd dir)
                      (vc-git--out-ok "ls-files" "-c" "-z" "--" name)
                      ;; If result is empty, use ls-tree to check for deleted
                      ;; file.
                      (when (eq (point-min) (point-max))
                        (vc-git--out-ok "ls-tree" "--name-only" "-z" "HEAD"
                                        "--" name))
                      (buffer-string))))
          (and str
               (> (length str) (length name))
               (string= (substring str 0 (1+ (length name)))
                        (concat name "\0"))))))))


>                 ;; path specs.
>                 ;; See also: http://marc.info/?l=git&m=125787684318129&w=2
>                 (name (file-relative-name file dir))
> -               (str (ignore-errors
> +               (str (with-demoted-errors "Error: %S"
>                        (cd dir)
>                        (vc-git--out-ok "ls-files" "-c" "-z" "--" name)
>                        ;; If result is empty, use ls-tree to check for deleted


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#18481: vc/vc-git.el: use `with-demoted-errors' instead of `ignore-errors'.

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Emilio Lopes <eclig@gmx.net> writes:
>
>> cf. http://lists.gnu.org/archive/html/bug-gnu-emacs/2014-09/msg00394.html
>>
>> --- lisp/ChangeLog    2014-09-15 00:20:21 +0000
>> +++ lisp/ChangeLog    2014-09-15 13:36:10 +0000
>> @@ -1,3 +1,14 @@
>> +2014-09-15  Emilio C. Lopes  <eclig@gmx.net>
>> +
>> +    * vc/vc-git.el (vc-git-registered): use `with-demoted-errors'
>> +    instead of `ignore-errors' so that the user is informed if
>> +    something unexpected happens.
>
> (I'm going through old bug reports that unfortunately have not received
> any responses yet.)
>
> So, in that URL Stefan suggested using with-demoted-errors instead of
> ignore-errors here, and that seems sensible.  But I'm wondering whether
> this code is expected to fail, and whether the errors (in that case) are
> totally uninteresting?
>
> I've done some testing (without the `ignore-errors'), and in my tests
> the code doesn't fail, so I think the patch suggested makes sense.
>
> Does this patch makes sense to everybody else, too?

I'm not a heavy user of vc, but FWIW it seems to me that it should be
safe enough to catch fewer errors.  Maybe we could just install it and
see what blows up, if the patch works for you...

> (defun vc-git-registered (file)
>   "Check whether FILE is registered with git."
>   (let ((dir (vc-git-root file)))
>     (when dir
>       (with-temp-buffer
>         (let* (process-file-side-effects
>                ;; Do not use the `file-name-directory' here: git-ls-files
>                ;; sometimes fails to return the correct status for relative
>                ;; path specs.
>                ;; See also: http://marc.info/?l=git&m=125787684318129&w=2
>                (name (file-relative-name file dir))
>                (str (ignore-errors
>                       (cd dir)
>                       (vc-git--out-ok "ls-files" "-c" "-z" "--" name)
>                       ;; If result is empty, use ls-tree to check for deleted
>                       ;; file.
>                       (when (eq (point-min) (point-max))
>                         (vc-git--out-ok "ls-tree" "--name-only" "-z" "HEAD"
>                                         "--" name))
>                       (buffer-string))))
>           (and str
>                (> (length str) (length name))
>                (string= (substring str 0 (1+ (length name)))
>                         (concat name "\0"))))))))
>
>
>>                 ;; path specs.
>>                 ;; See also: http://marc.info/?l=git&m=125787684318129&w=2
>>                 (name (file-relative-name file dir))
>> -               (str (ignore-errors
>> +               (str (with-demoted-errors "Error: %S"
>>                        (cd dir)
>>                        (vc-git--out-ok "ls-files" "-c" "-z" "--" name)
>>                        ;; If result is empty, use ls-tree to check for deleted

Best regards,
Stefan Kangas

bug#18481: vc/vc-git.el: use `with-demoted-errors' instead of `ignore-errors'.

[Dmitry Gutov]

On 12.08.2020 20:06, Stefan Kangas wrote:
> I'm not a heavy user of vc, but FWIW it seems to me that it should be
> safe enough to catch fewer errors.  Maybe we could just install it and
> see what blows up, if the patch works for you..

Yup.

bug#18481: vc/vc-git.el: use `with-demoted-errors' instead of `ignore-errors'.

[Lars Ingebrigtsen]

Dmitry Gutov <dgutov@yandex.ru> writes:

> On 12.08.2020 20:06, Stefan Kangas wrote:
>> I'm not a heavy user of vc, but FWIW it seems to me that it should be
>> safe enough to catch fewer errors.  Maybe we could just install it and
>> see what blows up, if the patch works for you..
>
> Yup.

OK, I've now done this.  And if it gets annoying in some use cases, the
patch should be reverted.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no