PY_SSIZE_T_CLEAN not defined

[menschel]

Hello, I ran into this issue after upgrading from Python 3.9 to Python 3.11 recently.

Apparently the MACRO PY_SSIZE_T_CLEAN must be defined in py3c.h before including python.h

https://docs.python.org/3/c-api/arg.html#strings-and-buffers

Otherwise it leads to
SystemError: PY_SSIZE_T_CLEAN macro must be defined for '#' formats

[encukou]

In addition to defining PY_SSIZE_T_CLEAN, you also need to ensure you use Py_ssize_t rather than int in any calls that use the # formats. So, py3c shouldn't simply define PY_SSIZE_T_CLEAN for you -- that would be inviting data corruption.

This should be explained in the text, however.

[menschel]

OK, if it's responsibility of the layer including py3c.h, I said nothing. Thanks.