[westurner]

> It would be a big help if CPython released a tool that could at least scan a C code base to detect free threaded issues, and ideally verify it is correct.

Create or extend a list of answers to:

What heuristics predict that code will fail in CPython's nogil "free threaded" mode?

[rogerbinns]

Some of that is already around, but scattered across multiple locations. For example there is a list in the Python doc:

https://docs.python.org/3/howto/free-threading-extensions.ht...

And a dedicated web site:

https://py-free-threading.github.io/

But as an example neither include PySequence_Fast which is in the json.c changes I pointed to. The folks doing the auditing of stdlib do have an idea of what they are looking for, and so would be best suited to keep a list (and tool) up to date with what is needed.

[westurner]

A list of Issue and PR URLs that identify and fix free threading issues would likely also be of use for building a 2to3-like tool to lint and fix C extensions to work with CPython free threading nogil mode