Subject: bug#57115: emacs 29 ~commandp~ check function ~find-file~ loop without termination while ~find-file~ is adviced nested up to 20 level

From: Pythonora Nybon <[email-masked]>
Date: Wed, 10 Aug 2022 08:55:09 +0800

Dear emacs maintenance team:

I found a seriously bug in the latest emacs master development branch
(i.e. the next-stage emacs 29 version) which may cause seriously
compatibility issues for older emacs users, please see the description
below:

# Description:

**NOTE: It's a seriously fatal bug**

It seems the new `oclosure` internal API invocation caused this issue
since it modified `advice` refers. And there's no problem in
emacs-28 and further older versions.

This bug will definitely broke the user emacs config compatibility
while they update to 29, since many user use **non-side-effects
advice** to inject their owns habits into the vanilla emacs
specification.

I use the `find-file` just as a example but the bug seemly effects on
most of the `advice` behaviour covered on others occasions.

Reproduce:

Insert below snippet as your `init.el` and run with vanilla emacs 29
session.

``` elisp

(toggle-debug-on-quit)
;; (toggle-frame-maximized)
;; (package-initialize)
(require 'files)
(require 'help)
(with-temp-message
    (substitute-command-keys
     (format
      "emacs %s is hang of `commandp' loop via advice to `find-file', \
please hint `\\[keyboard-quit]' to see the backtrace."
      emacs-major-version))
  (dotimes (cnt 20)
    (let ((sym (intern (format "test-advice/cnt-%s" cnt))))
      (eval
       `(progn
          (defun ,sym (&rest _)
            nil)
          (advice-add 'find-file :before ',sym)))))
  (commandp 'find-file))

```

# SYSTEM informations

```

In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.34, cairo version 1.17.6) of 2022-07-28 built on
 HOMEPC. Repository revision:
 163424e04b7f75a1655fd263ba4b6d6d4fa880b2 Repository branch: HEAD
 Windowing system distributor 'The X.Org Foundation', version
 11.0.12201003 System Description: Arch Linux

Configured using: 'configure --prefix=/usr/local/share/emacs/29.0.50/
 --with-mailutils --with-imagemagick'

Configured features: ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM
GSETTINGS HARFBUZZ IMAGEMAGICK JPEG JSON LCMS2 LIBOTF LIBSYSTEMD LIBXML2
M17N_FLT MODULES NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings: value of $LANG: en_US.UTF-8 locale-coding-system:
  utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect: tooltip-mode: t global-eldoc-mode: t eldoc-mode:
  t show-paren-mode: t electric-indent-mode: t mouse-wheel-mode: t
  tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t
  global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t
  line-number-mode: t indent-tabs-mode: t transient-mark-mode: t
  auto-composition-mode: t auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows: None found.

Features: (shadow sort mail-extr emacsbug message mailcap yank-media
puny dired dired-loaddefs rfc822 mml mml-sec password-cache epa derived
epg rfc6068 epg-config gnus-util text-property-search time-date subr-x
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils help-fns radix-tree cl-print byte-opt gv bytecomp
byte-compile cconv debug backtrace help-mode find-func cl-loaddefs
cl-lib cus-start cus-load rmc iso-transl tooltip eldoc paren electric
uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
faces cus-face macroexp files window text-properties overlay sha1 md5
base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit xinput2 x multi-tty make-network-process
emacs)

Memory information: ((conses 16 113315 7232) (symbols 48 7241 0)
(strings 32 19051 975) (string-bytes 1 602973) (vectors 16 11955)
(vector-slots 8 171420 9118) (floats 8 24 26) (intervals 56 5526 0)
(buffers 992 12))

```