bug#28850: 26.0.90; Error running timer 'jit-lock-stealth-fontify': (error "Invalid search bound (wrong side of point)")

[Basil L. Contovounesios]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Wed, 25 Oct 2017 19:11:37 +0000
>> Cc: 28850@debbugs.gnu.org
>> From: Alan Mackenzie <acm@muc.de>
>> 
>> Actually, it wasn't that difficult to amend that form generator.  Would
>> you please try out the patch below, which should apply cleanly to
>> master.
>
> I think you've solved the problem, because I let Emacs run idle for 10
> hours, and it didn't hit this error even once.

It seems to have returned in some way.  I can't reproduce this on Emacs
26, but on latest master, the following steps:

0. emacs -Q
1. (progn (setq debug-on-error t)
          (setq jit-lock-stealth-nice nil)
          (setq jit-lock-stealth-time 0)
          (find-function #'next-property-change))
2. C-x C-e

almost immediately lead to the following backtrace:

Debugger entered--Lisp error: (error "Invalid search bound (wrong side of 
point)")
  search-forward-regexp("\\<\\(\\(?:enum\\)\\)\\>[^][{};/#=]*{" 1673 t)
  c-font-lock-enum-body(1673)
  font-lock-fontify-keywords-region(1123 1673 nil)
  font-lock-default-fontify-region(1123 1673 nil)
  c-font-lock-fontify-region(1173 1673 nil)
  font-lock-fontify-region(1173 1673)
  #f(compiled-function (fun) #<bytecode 
0x1565bb8a9581>)(font-lock-fontify-region)
  run-hook-wrapped(#f(compiled-function (fun) #<bytecode 0x1565bb8a9581>) 
font-lock-fontify-region)
  jit-lock--run-functions(1173 1673)
  jit-lock-fontify-now(1173 1673)
  jit-lock-stealth-fontify(t)
  apply(jit-lock-stealth-fontify t)
  timer-event-handler([t 0 0 974323 nil jit-lock-stealth-fontify (t) idle 
261000])

I'm not sure if this says anything, but when the *Backtrace* buffer is
displayed, the textprop.c buffer is marked as modified.  Could this be
related to the before/after change machinery?

A similar error I occasionally see, but have not yet figured out how to
reproduce:

  Error during redisplay: (jit-lock-function 19569)
    signaled (error "Invalid search bound (wrong side of point)")

Thanks,

-- 
Basil

In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll 
bars)
 of 2019-04-30 built on thunk
Repository revision: f478082f9ff22ff41fbd9616ebea75757f9a0311
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12003000
System Description: Debian GNU/Linux buster/sid

Configured using:
 'configure 'CC=ccache gcc' 'CFLAGS=-O2 -march=native' --config-cache
 --prefix=/home/blc/.local --with-mailutils --with-x-toolkit=lucid
 --with-modules --with-file-notification=yes --with-x'

Configured features:
XAW3D XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS
GLIB NOTIFY INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT
LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS LUCID X11 XDBE XIM MODULES THREADS
LIBSYSTEMD JSON PDUMPER LCMS2 GMP

Package: CC Mode 5.33.2 (C/*l)
Buffer Style: GNU
c-emacs-features: (pps-extended-state col-0-paren posix-char-classes 
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current state:
==============
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