Re: EXC_BAD_ACCESS on Mac

[Paul Eggert]

On 06/17/13 12:44, Kazu Yamamoto (山本和彦) wrote:
> why is "first - row->glyphs[area]"
> equal to "last - row->glyphs[area]"?

It could be because of this code in draw_glyphs:

  /* Let's rather be paranoid than getting a SEGV.  */
  end = min (end, row->used[area]);
  start = clip_to_bounds (0, start, end);

Even if 'start < end' before this code
is executed, it could be that start == end afterwards.

What happens if you apply the following patch and compile
with -DENABLE_CHECKING?

=== modified file 'src/xdisp.c'
--- src/xdisp.c 2013-06-15 09:34:20 +0000
+++ src/xdisp.c 2013-06-17 22:31:35 +0000
@@ -23356,9 +23356,7 @@
 
   ALLOCATE_HDC (hdc, f);
 
-  /* Let's rather be paranoid than getting a SEGV.  */
-  end = min (end, row->used[area]);
-  start = clip_to_bounds (0, start, end);
+  eassert (0 <= start && start <= end && end <= row->used[area]);
 
   /* Translate X to frame coordinates.  Set last_x to the right
      end of the drawing area.  */