Re: Emacs aborts (xassert) when PageUp key used in semi-binary file

[Kim F. Storm]

Tim Van Holder <address@hidden> writes:

> This is probably related to the problem I reported this morning.
> This time I had a semi-binary file (some sort of mainframe file dump)
> open (i.e. there were lots of \nnn character respresentations in the
> buffer (plain old Fundamental mode).  Pressing PageUp when halfway
> through the file caused emacs to abort.

>
> gdb stacktrace:
>
> Breakpoint 1, abort () at $HOME/gnu/emacs/src/emacs.c:454
> 454       kill (getpid (), SIGABRT);
> (gdb) up
> #1  0x08072309 in move_it_vertically_backward (it=0xbfffc8c0, dy=0) at
> $HOME/gnu/emacs/src/xdisp.c:6296
> 6296          xassert (IT_CHARPOS (*it) <= start_pos);

I have seen the same trap once myself.
I suspect that the xassert is bogus, but I cannot prove it.

The assert seems logical, there are cases where moving backwards will
actually move forwards if start is in invisible / intangible /
continued / truncated parts of the buffer


Can you print these:

p dy
p start_pos
p *it
p it2
p it3

-- 
Kim F. Storm <address@hidden> http://www.cua.dk