What's the public API alternative to _PyObject_GC_IS_TRACKED()?

[Marco Sulla]

On Tue, 28 Dec 2021 at 12:38, Inada Naoki <songofacandy at gmail.com> wrote:
> Your case is special.
> You want to create a frozendict which performance is same to builtin dict.
> Builtin dict has special optimization which tightly coupled with
> current CPython implementation.
> So you need to use private APIs for MAINTAIN_TRACKING.

I solved this problem with a hacky trick: I included a reduced and
slightly modified version of dictobject.c. Furthermore I copy / pasted
stringlib\eq.h and _Py_bit_length. I'm currently doing this in a
refactor branch.
(Yes, I know that including a .c is very bad... but I need to do this
to separate the code of dict from the code of frozendict. Putting all
in the same files mess my head)

> But PyObject_GC_Track() is a public API.

The problem is I can't invoke PyObject_GC_Track() on an already
tracked object. I tried it and Python segfaulted. That's why CPython
uses _PyObject_GC_IS_TRACKED() before.

I'll try to copy/paste it too... :D but I do not understand why
there's not a public version of it.