I'm currently building an Emacs module to provide access to GSSAPI. In it,
I have to use the make_user_ptr() function in a few places. When creating a
user_ptr, the function accepts a pointer to a function which will be called
when the object is GC'ed.

The problem is that the free function is only called with a single
argument; the pointer itself. In my case, the underlying GSSAPI function
that releases the object may return some diagnostics, and I would like to
be able to call the Elisp function ‘warn’ with a message describing what
happened.

I think that the callback should accept 3 arguments instead of 1. In
addition to the pointer itself, the ‘emacs_env’ pointer is needed. An
arbitrary ‘void *data’ pointer would be useful too.

Regards,
Elias