gh-108494: AC supports pos-only args in limited C API

[vstinner]

AC now checks for "#define Py_LIMITED_API" pattern to use the limited C API.

• Issue: Add support for the limited C API to Argument Clinic #108494

[serhiy-storchaka]

It is not correct. In best case it is unused.

[vstinner]

Since AC and parsing arguments are complex, I propose to implement incrementally the limited C API. I'm not sure that I get your comment, when is it unused? Do you want to propose a fix?

[AlexWaygood]

@vstinner, would you be able to add some documentation for this change to https://docs.python.org/3/howto/clinic.html? It would be useful information for users of Argument Clinic to know that they can generate code that only uses the limited C API by adding #define Py_LIMITED_API to a file

[vstinner]

@vstinner, would you be able to add some documentation for this change to https://docs.python.org/3/howto/clinic.html? It would be useful information for users of Argument Clinic to know that they can generate code that only uses the limited C API by adding #define Py_LIMITED_API to a file

I wrote PR #108584 to document the Limited C API feature.