[SPARSE] seg fault problems.

[Ryan Anderson <ryan@michonline.com>]

For a while now, I've been getting a segfault everytime I run "check"
(even on a tree without any of my hackery in it.)

The segfault is here:
0x0804ff15 in add_ptr_list (listp=0x80609c0, ptr=0x40a04f84) at lib.c:207
207             if (!list || (nr = list->nr) >= LIST_NODE_NR) {

This is why:
(gdb) p *listp
$1 = (struct ptr_list *) 0x1

Tracking things back, I get:
(gdb) bt
#0  0x0804ff15 in add_ptr_list (listp=0x80609c0, ptr=0x40a04f84) at lib.c:207
#1  0x0804b855 in add_symbol (list=0x80609c0, sym=0x40a04f84) at lib.h:71
#2  0x0804b486 in parse_function_body (token=0x4066094c, decl=0x40a04f84, list=0x80609c0) at parse.c:1081
#3  0x0804b609 in external_declaration (token=0x40660884, list=0x80609c0) at parse.c:1121
#4  0x0804b832 in translation_unit (token=0x406607d0, list=0x80609c0) at parse.c:1167
#5  0x08048d44 in main (argc=7, argv=0xbffff774) at check.c:178

check.c:178 is:
        translation_unit(token, &used_list);

Putting a watch on used_list==0x1, it changes from 0 to 1 here:

preprocessor_if (token=0x4022664c, true=0) at pre-process.c:683
683             if (false_nesting || !true) {

or more accurately, here:
        if (false_nesting || !true) {
                false_nesting++;
                return 1;
        }

I'm completely not understanding what's going on here - used_list goes
from 0x0 to 0x1 a lot, and it doesn't seem to fail except in a path that
triggers in a few cases.

Got anything else I can do to help track this down?

-- 

Ryan Anderson
  sometimes Pug Majere