Bug report

Bug description:

In #127592 a new PyConfig flag was added for apple platforms to allow use of the system logger.

This PR looks like it was backported to all branches from 3.9 through to 3.13, and has been released in 3.13.2 and 3.12.9.

Unfortunately, this has changed the public ABI (layout of the PyConfig struct) on a patch release. This means that binaries using the PyConfig API and built using 3.13.1 or 3.13.0 (or 3.12.8) will potentially misbehave if running against a newer interpreter.

I picked this up after getting a PyO3 "FFI check" failure on 3.13.2, reporting that our FFI bindings were no longer compatible with CPython.

In PEP 741 it was previously noted that backporting a flag to break the public ABI was decided against, so I believe this to be a bug.

Do I wait for CPython to revert this? Or do I make PyO3 adjust to the new ABI (and break compatibility with all existing interpreters)?

ping @vstinner as I know you have been very active on this API.

CPython versions tested on:

3.13

Operating systems tested on:

macOS

Linked PRs

• [3.13] gh-130940: Remove PyConfig.use_system_logger #131129
• gh-130940: Modify default behavior of PyConfig.use_system_logger to enable on iOS #131172