gh-108494: Argument Clinic: inline parsing code for positional-only parameters in the limited C API by serhiy-storchaka · Pull Request #108622 · python/cpython
It fixes some code which uses private converters, like _PyLong_UnsignedShort_Converter. Inlined code only uses the limited C API.
But it still includes internal headers. It is difficult to not include them, because they are needed when the parsing code is not inlined, and this depends not only on the specified converter, but on other converters and other used features.
There is a behavior change: converters like _PyLong_UnsignedShort_Converter raise ValueError for negative integer, but the inlined code raise OverflowError. It is very difficult to detect negative integer in the limited C API. It can be fixed by changing exception in PyLong_AsUnsignedLong (see #74019).
I also reorganized the code for keyword parameters, so it will be easier to enable inlining once we add a public version of _PyArg_UnpackKeywords in the limited C API, which is the only stopper.
All tests (except one) are passed with using the limited C API (if possible).