Re: Likely bug: SMOBs and mark functions [Was: Re: [bug #30480] VM: load looks for files in the wrong directory]

[Ludovic Courtès]

Hi Luca!

Luca Saiu <address@hidden> writes:

> I've reproduced the problem by using the example in
>   doc/example-smob/
> which is much simpler than my own code; the failure is identical.
>
> address@hidden
> ~/projects-by-others/guile-from-git-mainline/doc/example-smob]$ ./myguile
> GNU Guile 1.9.15.114-b81eb
> Copyright (C) 1995-2011 Free Software Foundation, Inc.
>
> Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
> This program is free software, and you are welcome to redistribute it
> under certain conditions; type `,show c' for details.
>
> Enter `,help' for help.
> scheme@(guile-user)> make-image
> $1 = #<procedure make-image (_ _ _)>
> scheme@(guile-user)> (define i (make-image "Whistler's Mother" 100 100))
> scheme@(guile-user)> i
> $2 = #<image Whistler's Mother>
> scheme@(guile-user)> (gc)
> scheme@(guile-user)> (gc)
> The current thread is at (nil); Segmentation fault
>
> gdb says that the problem is in smob.c, in the smob_mark function:
>       SCM_I_CURRENT_THREAD->current_mark_stack_ptr = mark_stack_ptr;
> A quick printf showed me that the SCM_I_CURRENT_THREAD macro returned NULL.
>
> This happens on an x86_64 GNU/Linux machine, guile from today's git; 1.8
> doesn't crash.

I can’t reproduce the problem on x86_64-linux-gnu with a recent CVS
snapshot of libgc.  Which libgc do you use?

Thanks,
Ludo’.