bug#22982: 25.0.92; Forms Mode seems to fail to open data file

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[N. Jackson]

I get the error "Wrong-type-argument: stringp, nil" when I try to start
Forms Mode with

    M-x forms-find-file RET ~/Documents/test-forms.el RET

The backtrace is:

    Debugger entered--Lisp error: (wrong-type-argument stringp nil)
      expand-file-name(nil)
      find-file-noselect(nil)
      forms-mode(t)
      forms-find-file("~/Documents/test-forms.el")
      funcall-interactively(forms-find-file "~/Documents/test-forms.el")
      call-interactively(forms-find-file record nil)
      command-execute(forms-find-file record)
      execute-extended-command(nil "forms-find-file" nil)
      funcall-interactively(execute-extended-command nil "forms-find-file" nil)
      call-interactively(execute-extended-command nil nil)
      command-execute(execute-extended-command)

My forms control file (~/Documents/test-forms.el) is as follows:

    ;; This demo visits ‘/etc/passwd’.

    (setq forms-file "/etc/passwd")
    (setq forms-number-of-fields 7)
    (setq forms-read-only t)                 ; to make sure
    (setq forms-field-sep ":")
    ;; Don’t allow multi-line fields.
    (setq forms-multi-line nil)

    (setq forms-format-list
          (list
           "====== /etc/passwd ======\n\n"
           "User : "    1
           "   Uid: "   3
           "   Gid: "   4
           "\n\n"
           "Name : "    5
           "\n\n"
           "Home : "    6
           "\n\n"
           "Shell: "    7
           "\n"))

which is copied directly from the example in the Forms manual
(info "(forms) Format Description"). And /etc/passwd exists and is
accessible from Emacs.

I get exactly the same error with all forms control files I've tried,
even something as seemingly simple as:

    (setq forms-file "~/test-forms.dat")
    (setq forms-number-of-fields 2)
    (setq forms-format-list
          (list
           "Field1 : "    1
           "Field2 : "    2
           "\n"))

with a not yet existent data file.

Note: I checked Emacs 24.5 and I found I get the same error there.


In GNU Emacs 25.0.92.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.18.7)
 of 2016-03-03 built on moondust
Windowing system distributor 'Fedora Project', version 11.0.11800000
System Description:	Fedora release 23 (Twenty Three)

Configured using:
 'configure --prefix=/home/nlj/local/ --enable-checking=yes,glyphs
 'CFLAGS=-O0 -g3 -ggdb''

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11

Important settings:
  value of $LC_MONETARY: en_DK.utf8
  value of $LC_NUMERIC: en_DK.utf8
  value of $LC_TIME: en_DK.utf8
  value of $LANG: en_CA.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: IBuffer

Minor modes in effect:
  recentf-mode: t
  display-battery-mode: t
  display-time-mode: t
  delete-selection-mode: t
  savehist-mode: t
  save-place-mode: t
  electric-pair-mode: t
  desktop-save-mode: t
  cua-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  size-indication-mode: t
  column-number-mode: t
  line-number-mode: t
  global-visual-line-mode: t
  visual-line-mode: t
  transient-mark-mode: t

Recent messages:
Indenting region...done
Saving file /home/nlj/Documents/test-forms.el...
Wrote /home/nlj/Documents/test-forms.el
Entering debugger...
Making completion list...
mwheel-scroll: End of buffer
<mouse-6> is undefined
mwheel-scroll: Beginning of buffer [2 times]
Updating buffer list...done
Commands: m, u, t, RET, g, k, S, D, Q; q to quit; h for help
Quit

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bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[John Mastro]

N. Jackson <nljlistbox2@gmail.com> wrote:
> I get the error "Wrong-type-argument: stringp, nil" when I try to start
> Forms Mode with
>
>     M-x forms-find-file RET ~/Documents/test-forms.el RET
>
> The backtrace is:
>
>     Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>       expand-file-name(nil)
>       find-file-noselect(nil)
>       forms-mode(t)
>       forms-find-file("~/Documents/test-forms.el")
>       funcall-interactively(forms-find-file "~/Documents/test-forms.el")
>       call-interactively(forms-find-file record nil)
>       command-execute(forms-find-file record)
>       execute-extended-command(nil "forms-find-file" nil)
>       funcall-interactively(execute-extended-command nil "forms-find-file" nil)
>       call-interactively(execute-extended-command nil nil)
>       command-execute(execute-extended-command)

Confirmed on Emacs 25.

This seems to be caused by the call ‘(set-visited-file-name nil)’ in
‘forms-mode’. Before that call, ‘forms-file’ is "/etc/passwd";
afterward, it is nil.

-- 
john

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[John Mastro]

John Mastro <john.b.mastro@gmail.com> wrote:
> Confirmed on Emacs 25.
>
> This seems to be caused by the call ‘(set-visited-file-name nil)’ in
> ‘forms-mode’. Before that call, ‘forms-file’ is "/etc/passwd";
> afterward, it is nil.

To clarify, the result is the same if you visit the control file via the
normal ‘find-file’ and invoke ‘M-x forms-mode’.

Also, I confirmed that commenting out ‘(set-visited-file-name nil)’
prevents the error, though that's unlikely to be the right fix on its
own.

-- 
john

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[Eli Zaretskii]

> From: nljlistbox2@gmail.com (N. Jackson)
> Date: Thu, 10 Mar 2016 19:46:17 -0400
> 
> I get the error "Wrong-type-argument: stringp, nil" when I try to start
> Forms Mode with
> 
>     M-x forms-find-file RET ~/Documents/test-forms.el RET
> 
> The backtrace is:
> 
>     Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>       expand-file-name(nil)
>       find-file-noselect(nil)
>       forms-mode(t)
>       forms-find-file("~/Documents/test-forms.el")
>       funcall-interactively(forms-find-file "~/Documents/test-forms.el")
>       call-interactively(forms-find-file record nil)
>       command-execute(forms-find-file record)
>       execute-extended-command(nil "forms-find-file" nil)
>       funcall-interactively(execute-extended-command nil "forms-find-file" nil)
>       call-interactively(execute-extended-command nil nil)
>       command-execute(execute-extended-command)
> 
> My forms control file (~/Documents/test-forms.el) is as follows:
> 
>     ;; This demo visits ‘/etc/passwd’.
> 
>     (setq forms-file "/etc/passwd")
>     (setq forms-number-of-fields 7)
>     (setq forms-read-only t)                 ; to make sure
>     (setq forms-field-sep ":")
>     ;; Don’t allow multi-line fields.
>     (setq forms-multi-line nil)
> 
>     (setq forms-format-list
>           (list
>            "====== /etc/passwd ======\n\n"
>            "User : "    1
>            "   Uid: "   3
>            "   Gid: "   4
>            "\n\n"
>            "Name : "    5
>            "\n\n"
>            "Home : "    6
>            "\n\n"
>            "Shell: "    7
>            "\n"))
> 
> which is copied directly from the example in the Forms manual
> (info "(forms) Format Description"). And /etc/passwd exists and is
> accessible from Emacs.
> 
> I get exactly the same error with all forms control files I've tried,
> even something as seemingly simple as:
> 
>     (setq forms-file "~/test-forms.dat")
>     (setq forms-number-of-fields 2)
>     (setq forms-format-list
>           (list
>            "Field1 : "    1
>            "Field2 : "    2
>            "\n"))
> 
> with a not yet existent data file.

I cannot reproduce this, neither with the 25.0.92 pretest nor with the
current emacs-25 branch.  I tried both control files, and they both
worked (although I needed to change the file names a bit to adapt them
to my system's directory hierarchy).

Does this happen for you in "emacs -Q"?

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[Eli Zaretskii]

> From: John Mastro <john.b.mastro@gmail.com>
> Date: Thu, 10 Mar 2016 16:14:32 -0800
> Cc: "N. Jackson" <nljlistbox2@gmail.com>
> 
> This seems to be caused by the call ‘(set-visited-file-name nil)’ in
> ‘forms-mode’. Before that call, ‘forms-file’ is "/etc/passwd";
> afterward, it is nil.

Sorry, I don't see how this is related.  According to the backtrace,
find-file-noselect is called with an argument of nil, and I don't
understand how this could happen, since the call I see:

  ;; find the data file
  (setq forms--file-buffer (find-file-noselect forms-file))

invokes find-file-noselect with an argument that cannot be nil, and
has no relation to the visited-file's name.

There's another call to find-file-noselect, in
forms--intuit-from-file, but that one also uses forms-file, after
verifying that it exists (which is not the case in point):

      ;; Need a file to do this.
      (if (not (file-exists-p forms-file))
	  (error "Need existing file or explicit `forms-number-of-fields'")

	;; Visit the file and extract the first record.
	(setq forms--file-buffer (find-file-noselect forms-file))

So I don't see how the problem could happen, and I definitely don't
understand how it is related to the set-visited-file-name call.

Does the problem happen to you in "emacs -Q"?

Thanks.

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[Eli Zaretskii]

> From: John Mastro <john.b.mastro@gmail.com>
> Date: Thu, 10 Mar 2016 16:19:26 -0800
> Cc: "N. Jackson" <nljlistbox2@gmail.com>
> 
> To clarify, the result is the same if you visit the control file via the
> normal ‘find-file’ and invoke ‘M-x forms-mode’.

I tried this as well, and it didn't signal an error here.

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[N. Jackson]

Hi Eli and John,

At 16:14 -0800 on Thursday 2016-03-10, John Mastro wrote:
>
> Confirmed on Emacs 25.
>
> This seems to be caused by the call ‘(set-visited-file-name nil)’ in
> ‘forms-mode’. Before that call, ‘forms-file’ is "/etc/passwd";
> afterward, it is nil.

At 12:26 +0200 on Friday 2016-03-11, Eli Zaretskii wrote:
>
> Does this happen for you in "emacs -Q"?

No. I apologise for missing this. The problem does not occur for me with
`emacs -Q', neither in 25.0.92 nor 24.5.

I will bisect my init file and report back.

Thanks,
N.

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[N. Jackson]

At 08:49 -0400 on Friday 2016-03-11, N. Jackson wrote:
>
> I will bisect my init file and report back.

The verdict is that, for me, the problem is caused by this Custom-set
variable:

    '(major-mode (quote text-mode))

Regards,
N.

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[Eli Zaretskii]

> From: nljlistbox2@gmail.com (N. Jackson)
> Cc: 22982@debbugs.gnu.org,  John Mastro <john.b.mastro@gmail.com>
> Date: Fri, 11 Mar 2016 09:25:15 -0400
> 
> At 08:49 -0400 on Friday 2016-03-11, N. Jackson wrote:
> >
> > I will bisect my init file and report back.
> 
> The verdict is that, for me, the problem is caused by this Custom-set
> variable:
> 
>     '(major-mode (quote text-mode))

Hmm... I'm still not following.  Can you tell how to modify your
recipe such that it will reproduce the problem in "emacs -Q"?

Thanks.

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[N. Jackson]

At 17:02 +0200 on Friday 2016-03-11, Eli Zaretskii wrote:
>
> Hmm... I'm still not following.  Can you tell how to modify your
> recipe such that it will reproduce the problem in "emacs -Q"?
>
> Thanks.

0.  cat > ~/test-forms-control-file.el
    (setq forms-file "/etc/passwd")
    (setq forms-number-of-fields 7)
    (setq forms-read-only t)
    (setq forms-field-sep ":")
    (setq forms-multi-line nil)
    (setq forms-format-list
          (list
           "====== /etc/passwd ======\n\n"
           "User : "    1
           "   Uid: "   3
           "   Gid: "   4
           "\n\n"
           "Name : "    5
           "\n\n"
           "Home : "    6
           "\n\n"
           "Shell: "    7
           "\n"))
    ^D

1.  emacs -Q

2.  M-: (custom-set-variables '(major-mode (quote text-mode))) RET

3.  M-x forms-find-file RET C-S-backspace ~/test-forms-control-file.el RET


This recipe results in the error

    find-file-noselect: Wrong type argument: stringp, nil

whereas, if Step 2 is omitted, Forms Mode works correctly.

I hope this helps. Please let me know if I can provide any more
information.

Regards,
N.

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[Eli Zaretskii]

> From: nljlistbox2@gmail.com (N. Jackson)
> Cc: 22982@debbugs.gnu.org,  john.b.mastro@gmail.com
> Date: Fri, 11 Mar 2016 12:11:20 -0400
> 
> 1.  emacs -Q
> 
> 2.  M-: (custom-set-variables '(major-mode (quote text-mode))) RET
> 
> 3.  M-x forms-find-file RET C-S-backspace ~/test-forms-control-file.el RET
> 
> 
> This recipe results in the error
> 
>     find-file-noselect: Wrong type argument: stringp, nil
> 
> whereas, if Step 2 is omitted, Forms Mode works correctly.

Thanks, I think I fixed this on the emacs-25 branch.

bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[N. Jackson]

At 13:07 +0200 on Saturday 2016-03-12, Eli Zaretskii wrote:
>
> Thanks, I think I fixed this on the emacs-25 branch.

I can confirm that with your fix Forms Mode is now working with
customised major-mode. Thanks Eli (and John). Closing.

N.