Re: crash on MacOSX

[Liang Wang]

On Sat, Aug 18, 2012 at 12:35 PM, Liang Wang <address@hidden> wrote:
> Hi,
>
> I build latest trunk (--with-ns) on Mac OS X 10.7.4 but it fails to start.
>
> Error message is
>
> ~/src/emacs/trunk$ ./nextstep/Emacs.app/Contents/MacOS/Emacs -Q
> Arithmetic error
>
> Here is backtrace.
>
> ~/src/emacs/trunk$ gdb --args ./nextstep/Emacs.app/Contents/MacOS/Emacs -Q
> GNU gdb 6.3.50-20050815 (Apple version gdb-1708) (Thu Nov  3 21:59:02 UTC 
> 2011)
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "x86_64-apple-darwin"...Reading symbols for
> shared libraries .......... done
>
> (gdb) r
> Starting program:
> /Users/wangliang/src/emacs/trunk/nextstep/Emacs.app/Contents/MacOS/Emacs
> -Q
> Reading symbols for shared libraries
> +++++++++.............................................................................................................................
> done
> Reading symbols for shared libraries . done
> Reading symbols for shared libraries . done
> Reading symbols for shared libraries . done
> Reading symbols for shared libraries . done
>

This bug is not always reproducible when I debug it inside gdb.  Is it
possible that it depends on the loading order of shared libraries?
When emacs starts successfully, the list of message, "Reading symbols
for shared libraries", is longer.

There are two ways to work around this bug.  One is to revert r109641:
Fix average font width  calculation on NS.
http://lists.gnu.org/archive/html/emacs-diffs/2012-08/msg00322.html.
font->average_width is set to zero when bug occurs.

I'm not sure if it is related to this patch directly.  Since, the
other way is to compile nsfont.m with -g3 -O0.


Liang