Re: crash on MacOSX

[Eli Zaretskii]

> Date: Sat, 18 Aug 2012 18:33:57 +0800
> From: Liang Wang <address@hidden>
> Cc: Chong Yidong <address@hidden>
> 
> 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?

Unlikely.  The original crash was reported here:

      int font_wid = FRAME_COLUMN_WIDTH (f);
      int cols = (left_wid + right_wid + font_wid-1) / font_wid; <<<<<

As you see, font_wid is computed from FRAME_COLUMN_WIDTH (f), which
should never be zero.  I fail to see how this could be dependent on
the order of loading shared libraries.  This value depends on the font
used by the default face of the first frame created when Emacs starts.
It does not come from any library.

But of course, this is software, so anything's possible.

> When emacs starts successfully, the list of message, "Reading symbols
> for shared libraries", is longer.

When it does NOT crash, what is the value of font_wid in the above
snippet?

> 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.

Most probably, this is the reason for the bug.