bug#64793: 28.2; python-mode: two single quotes makes emacs stop echoing and seem to hang

[Akkana Peck]

1. Save the following file (minimal test example) as bug.py:

---- begin file -----
#!/usr/bin/env python3

def one_function():
    print()

    return 42


def another_function(filename):
    """
    With a docstring here, if you place the cursor between the two
    lines of one_function, hit tab to indent 4 spaces, then type
    two single quotes, '', emacs seems to lock up: the quotes aren't
    echoed and neither is anything else you type after that.
    But a Ctrl-G will wake emacs up and make the quotes and anything
    else you typed appear. Depending on your emacs config, you might
    need a double Ctrl-G.
    """
    pass
---- end file -----

2. Run emacs -Q bug.py

3. Go to line 5, the blank line between the print() and the return.

4. Hit TAB, which should automatically indent 4 spaces to match the two
existing lines.

5. Type two single quotes '' -- note that the quotes do not echo.
Try typing more characters, or moving up or down ... nothing works.
In fact, try hiding then re-showing the window, or going to another
virtual desktop then back to where the emacs window is: it doesn't even
redraw, seems to be locked up hard.

But it isn't really, because ^G^G will wake emacs up (sometimes a single
^G works, sometimes I need two, depending on what other packages are loaded).


In GNU Emacs 28.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.37, cairo 
version 1.16.0)
 of 2023-05-13, modified by Debian built on x86-ubc-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12101007
System Description: Debian GNU/Linux trixie/sid

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/libexec
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-libsystemd --with-pop=yes
 
--enable-locallisppath=/etc/emacs:/usr/local/share/emacs/28.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/28.2/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils
 --with-native-compilation --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/libexec
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-libsystemd --with-pop=yes
 
--enable-locallisppath=/etc/emacs:/usr/local/share/emacs/28.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/28.2/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils
 --with-native-compilation --with-cairo --with-x=yes
 --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
 -ffile-prefix-map=/build/emacs-mPr7Vr/emacs-28.2+1=. -fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
 -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

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

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

Major mode: Python

Minor modes in effect:
  shell-dirtrack-mode: t
  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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg rfc6068 epg-config gnus-util rmail
rmail-loaddefs text-property-search mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils python tramp-sh comp
comp-cstr warnings rx cl-extra help-mode tramp tramp-loaddefs trampver
tramp-integration files-x tramp-compat shell pcomplete parse-time
iso8601 time-date ls-lisp format-spec auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json subr-x map seq
byte-opt gv bytecomp byte-compile cconv comint ring cl-loaddefs cl-lib
ansi-color 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 cl-generic 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 simple abbrev obarray cl-preloaded nadvice button
loaddefs faces cus-face macroexp files window text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process
native-compile emacs)

Memory information:
((conses 16 119398 9279)
 (symbols 48 9843 1)
 (strings 32 31623 2880)
 (string-bytes 1 1115369)
 (vectors 16 20828)
 (vector-slots 8 389974 19791)
 (floats 8 38 36)
 (intervals 56 476 0)
 (buffers 992 13))