GNU bug report logs - #38691
CC Mode 5.34 (C++//lhw); `Invalid search bound` when undo

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From: Alan Mackenzie <acm <at> muc.de>
To: "Sun, Wei" <waysun <at> amazon.com>
Cc: 38691 <at> debbugs.gnu.org
Subject: bug#38691: CC Mode 5.34 (C++//lhw); `Invalid search bound` when undo
Date: Wed, 22 Jan 2020 20:28:23 +0000

Hello again, Wei.

I have now committed the fix to call_process (see below) to the emacs-27
branch at savannah.gnu.org, so the bug should now be fixed in that
branch.  The fix should find its way into the master branch sometime
soon.

Could you possibly see your way to testing the bug fix on the emacs-27
branch with your real code, please, so that we can be sure the bug is
actually fixed?  Then I can close the bug as fixed.

Again, thanks for taking the trouble to report this bug, and thanks also
for cutting your test case down to a convenient, easy to work with,
minimum.


On Tue, Dec 24, 2019 at 11:16:33 +0000, Alan Mackenzie wrote:
> Hello, Wei.

> Thanks for taking the trouble to report this bug, and thanks for
> including a CC Mode configuration dump.


> On Fri, Dec 20, 2019 at 10:13:32 +0000, Sun, Wei via CC-Mode-help wrote:
> > Package: cc-mode

> > $> cat test.cpp
> > // 2019-12-20 17:57

> > emacs -Q test.cpp

> > M-x mark-page RET
> > C-u M-x shell-command-on-region RET
> > sort RET
> > M-x undo RET

> > Debugger entered--Lisp error: (error "Invalid search bound (wrong side of point)")
> >   search-forward-regexp("R\"\\([^ ()\\\n\15\11]\\{0,16\\}\\)(" -20 bound)
> >   c-after-change-unmark-raw-strings(1 1 21)
> >   #f(compiled-function (fn) #<bytecode 0x91e275>)(c-after-change-unmark-raw-strings)
> >   mapc(#f(compiled-function (fn) #<bytecode 0x91e275>) (c-depropertize-new-text c-after-change-escape-NL-in-string c-after-change-unmark-raw-strings c-parse-quotes-after-change c-after-change-mark-abnormal-strings c-extend-font-lock-region-for-macros c-neutralize-syntax-in-CPP c-restore-<>-properties c-change-expand-fl-region))
> >   c-after-change(1 1 21)
> >   primitive-undo(1 ((1 . 22) (#("// 2019-12-20 17:57\n\n" 0 1 (face font-lock-comment-delimiter-face c-is-sws t c-in-sws t fontified t) 1 3 (face font-lock-comment-delimiter-face c-in-sws t fontified t) 3 20 (face font-lock-comment-face c-in-sws t fontified t) 20 21 (fontified t c-is-sws t)) . 1) (#<marker at 1 in test.cpp> . -21) (#<marker in no buffer> . -21) (#<marker at 1 in test.cpp> . -21) (t 24060 40235 192206 220000) nil (#("-" 0 1 (fontified t)) . 1) nil (#("#include <test.hpp>" 0 1 (face font-lock-preprocessor-face c-is-sws t c-in-sws t fontified t) 1 8 (face font-lock-preprocessor-face c-in-sws t fontified t) 8 9 (c-in-sws t fontified t) 9 10 (category c-<-as-paren-syntax face font-lock-string-face c-in-sws t fontified t) 10 18 (face font-lock-string-face c-in-sws t fontified t) 18 19 (category c->-as-paren-syntax face font-lock-string-face c-in-sws t fontified t)) . 22) (t 24060 40193 724383 390000)))
> >   undo-more(1)
> >   undo(nil)
> >   funcall-interactively(undo nil)
> >   call-interactively(undo nil nil)
> >   command-execute(undo)

> The cause of the bug is in the C routine call_process in the Emacs core.
> This function calls the external process, and (in this case) writes its
> output to an Emacs buffer.  When it does this, it calls the Emacs hook
> `before-change-functions' (as it should), but fails to call
> `after-change-functions'.  (These two hooks are documented in the Elisp
> manual on page "Change Hooks".)

> This failure to call `after-change-functions' confuses CC Mode.  CC Mode
> does have a workaround for this sort of thing, but it is not good enough
> to correct for the bug in call_process in this case.

> So....  I think the CC Mode workaround needs to be improved.  I will be
> looking at this.  Also, I am currently negotiating with Eli Zaretskii
> (the principle Emacs maintainer) to fix call_process.  I am confident
> this will happen.

> I'm hoping that a fix will be in the Emacs-27 release branch (which was
> created yesterday) within the next week or so.

> > Package: cc-mode

> > Emacs  : GNU Emacs 27.0.50 (build 6, x86_64-pc-linux-gnu, GTK+ Version 3.18.9)
> >  of 2019-12-20
> > Package: CC Mode 5.34 (C++//lhw)
> > Buffer Style: google
> > c-emacs-features: (pps-extended-state col-0-paren posix-char-classes gen-string-delim gen-comment-delim syntax-properties 1-bit)

> [ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).

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