GeezerVison

Test PySlice_Check(), PySlice_New(), PySlice_GetIndices(), PySlice_Unpack(), PySlice_AdjustIndices() and PySlice_GetIndicesEx().

PySlice_GetIndicesEx() is tested both as a macro and as a deprecated function, including the case when __index__() resizes the sequence whose size is passed as the length: the macro evaluates it after PySlice_Unpack(), the function before the call.

(cherry picked from commit 8c056c3)

The conflicts were only in the registration lists, which have diverged from main: Modules/Setup.stdlib.in, Modules/_testlimitedcapi.c, Modules/_testlimitedcapi/parts.h and the two PCbuild files. Modules/_testlimitedcapi has no slots.c here, so slice.c is registered between set.c and sys.c, and the registration calls are in PyInit__testlimitedcapi(), which returns PyObject *, so the new check returns NULL instead of -1.

In Modules/_testlimitedcapi/slice.c, Py_TARGET_ABI3T does not exist in 3.14 -- there is no Include/pyabi.h -- so the limited C API is simply not tested in a free-threading build, like in the other files of Modules/_testlimitedcapi.

• Issue: Add C API tests for the slice C API #158102