Assertion failures from `_interpchannels._register_end_types`

[devdanzin]

Crash report

What happened?

It's possible to abort a debug build by calling _interpchannels._register_end_types with invalid values:

import _interpchannels

_interpchannels._register_end_types(int, int)

Abort on 3.13:

python: Python/crossinterp_data_lookup.h:260: _PyCrossInterpreterData_RegisterClass: Assertion `matched->getdata == getdata' failed.
Aborted

Abort on main:

python: Python/crossinterp_data_lookup.h:271: _PyXIData_RegisterClass: Assertion `matched->getdata == getdata' failed.
Aborted

Found using fusil by @vstinner.

CPython versions tested on:

3.13, 3.14, CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.13.0+ (heads/3.13:746a0c5, Nov 20 2024, 21:39:05) [GCC 13.2.0]

[ZeroIntensity]

I'm not sure this is worth fixing. _interpchannels is completely private--the difference with _intepreters is that it's eventually going to be exposed publicly with PEP 734 as a wrapper over it.