Hello, I inserted a GC_is_visible check in my code and learned that 'symbols' is visible, but the things it points to were getting garbage collected anyway. It seemed like a GC bug, so I'm trying to build Guile with the latest version of GC and hoping that fixes it.
I just wanted to warn everyone that the GC_get_free_space_divisor function will break with libgc 7.2alpha6, because libgc includes the same function with the same name. I'm not sure what to do about that - probably try to automatically discover it in configure and put more #ifdefs around our definition (gc.c:212). Noah On Thu, Feb 2, 2012 at 9:59 PM, Noah Lavine <noah.b.lav...@gmail.com> wrote: > Got it! And unfortunately, it's a GC error. Here's what happens: > > symbols is an SCM object defined in symbols.c. It points to an > scm_cell_t which has two elements: a type tag, and a pointer to an > scm_weak_set_t. That scm_cell_t is at 0x10101cff0. > > However, that scm_cell_t is garbage collected in the scm_cons at > symbols.c:250. The reason it gets filled with SCM_EOL is that the cons > is scm_cons (SCM_BOOL_F, SCM_EOL). So I expect that the scm_cell_t is > garbage collected and then immediately reclaimed to be the pair, which > would result in its second cell being filled with SCM_EOL, which would > explain why we later extract SCM_EOL from it. > > As a test, I changed the variable 'symbols' in symbols.c to be > non-static. That didn't fix it, but then again, I don't really know > how GC works yet. > > I can read the libgc documentation and try to figure this out, but can > anyone point me to what I should be looking for? > > Thanks, > Noah > > On Wed, Feb 1, 2012 at 4:01 AM, Andy Wingo <wi...@pobox.com> wrote: >> On Wed 01 Feb 2012 03:12, Noah Lavine <noah.b.lav...@gmail.com> writes: >> >>> In the failing call, >>> the SCM 'symbols' is 0x10101cff0, but the failing set is at 0x304, >>> which has not been allocated. >> >> 0x304 is one of the iflags, SCM_EOL I think. >> >> So, I know it might not have anything to do with it, but can you verify >> that your guile includes patch 0aed71aa51e89e714de2392c2a5f44694dca77ea >> ? I just committed that last night, and although it does not seem to be >> related, who knows. >> >> Andy >> -- >> http://wingolog.org/