bug#46796: Cuirass & pointer finalization.

[Mathieu Othacehe <othacehe@gnu.org>]

Hello,

I'm trying to fix a memory corruption in the remote-server process of
Cuirass since a few days. Even though I don't have a usable core dump
file yet, I'm pretty sure the error comes from the "zmq-msg-init"
procedure of Guile-Simple-ZMQ.

This procedure creates a bytevector, call the C function zmq_msg_init to
initialize it, adds zmq_msg_close as pointer finalizer and returns a
wrapped pointer.

My understanding is that the wrapped pointer that is passed around in
Cuirass ensures that the underlying bytevector is not garbage collected
until the pointer goes out of scope. However, some assertions failures
such as this one:

--8<---------------cut here---------------start------------->8---
Assertion failed: check () (src/msg.cpp:394)
--8<---------------cut here---------------end--------------->8---

let me think that the bytevector is garbage collected, while ZMQ is
still using it. Some help would be much appreciated here :).

Thanks,

Mathieu