Re: SIGSEGV -- redisplay bug

[Richard Stallman]

    1185      /* Increment positions in glyphs.  */
    1186      for (area = 0; area < LAST_AREA; ++area)
    1187        for (i = 0; i < row->used[area]; ++i)
    1188          if (BUFFERP (row->glyphs[area][i].object)
    1189              && row->glyphs[area][i].charpos > 0)
    1190            row->glyphs[area][i].charpos += delta;
    1191
    1192      /* Capture the case of rows displaying a line end.  */
    (gdb) p area
    $1 = 4011656

It looks impossible to me--at least if there is no bizarre form of
aliasing.

Could you examine the data and verify that there was no aliasing
that would have caused clobberage of the value of area?
Where is area stored?  (Do `i ad area'.)

Would  row->glyphs[area][i].charpos  ever have aliased with area?