bug#891: 23.0.60; Emacs aborts after buffer-swap-text

[Stephen Berman]

On Thu, 04 Sep 2008 23:52:45 -0400 Stefan Monnier <monnier@iro.umontreal.ca> 
wrote:

>> 1. emacs -Q
>> 2. Load the library tabbar.el, available from
>> http://emhacks.cvs.sourceforge.net/emhacks/emhacks/tabbar.el?revision=1.69&view=markup
>> 3. M-x tabbar-mode
>> 4. M-: (buffer-swap-text (get-buffer "*Messages*"))
>> 5. C-c C-right (tabbar-forward)
>>    ==> Emacs aborts
>
>> The full backtrace is below.  According to the Lisp backtrace, the abort
>> occurs during or after switch-to-buffer.  Yet typing C-x b after step 4
>> above does not make Emacs abort.  Moreover, when I directly call any of
>> the tabbar.el functions listed in the backtrace and step through them
>> with edebug, this also fails to make Emacs abort.  Yet the above recipe
>> is reliably reproducible.  
>
>> (Since the abort occurs in unshow_buffer, my guess, based on a comment
>> at line 8314 of xdisp.c, is that switch-to-buffer needs to have
>> something like the code in with_echo_area_buffer that changes w->pointm.
>> I guess this would go after the call to Fset_buffer in switch-to-buffer,
>> but I don't know how to write the code.)
>
> Does the patch below fix the crash you see?

Yes; thanks!

Steve Berman