gc: bug: finalization logic causing gc assert

This problem was introduced on Feb 18, 2019 in commit
3931df5cba3d826511503ad1c0a5b84c1363765e.

Explicit finalization of objects outside of GC can
trigger an assertion in a later GC pass.

* gc.c (call_finalizers_impl): We simply must not have
duplicate entries in fresh_obj; this causes problems for
sweep_one. Under Valgrind debugging, sweep_one protects the
memory of processed entries, so a duplicate visit triggers bad
accesses. A more serious issue is that this function can be
called outside of gc, explicitly, since it is available as an
API function. So that is to say, non-garbage objects can have
their finalizers called ouside of GC. If this function is
called explicitly, outside of GC, it can end up doing
something stupid, like adding a generation 1 object into the
freshobj array, triggering an assert. We address this by not
doing any of that processing if GC is not taking place.

0 files changed, 0 insertions, 0 deletions