gh-106084: Remove _PyObject_RealIsInstance() function (#106106)

Remove the following functions from the public C API:

* _PyObject_RealIsInstance()
* _PyObject_RealIsSubclass()
* _Py_add_one_to_index_F()
* _Py_add_one_to_index_C()

Move _PyObject_RealIsInstance() and _PyObject_RealIsSubclass() to the
internal C API (pycore_abstract.h) and no longer export their symbols
(in libpython).

Make _Py_add_one_to_index_F() and _Py_add_one_to_index_C() functions
static: no longer export them.

2 files changed, 11 insertions, 12 deletions

diff --git a/Include/cpython/abstract.h b/Include/cpython/abstract.h
index cba0f4c..5eb22ff 100644
--- a/Include/cpython/abstract.h
+++ b/Include/cpython/abstract.h
@@ -147,18 +147,10 @@ PyAPI_FUNC(Py_ssize_t) PyObject_LengthHint(PyObject *o, Py_ssize_t);
 
 /* === Mapping protocol ================================================= */
 
-PyAPI_FUNC(int) _PyObject_RealIsInstance(PyObject *inst, PyObject *cls);
-
-PyAPI_FUNC(int) _PyObject_RealIsSubclass(PyObject *derived, PyObject *cls);
-
-/* For internal use by buffer API functions */
-PyAPI_FUNC(void) _Py_add_one_to_index_F(int nd, Py_ssize_t *index,
-                                        const Py_ssize_t *shape);
-PyAPI_FUNC(void) _Py_add_one_to_index_C(int nd, Py_ssize_t *index,
-                                        const Py_ssize_t *shape);
-
-/* Convert Python int to Py_ssize_t. Do nothing if the argument is None. */
+// Convert Python int to Py_ssize_t. Do nothing if the argument is None.
+// Cannot be moved to the internal C API: used by Argument Clinic.
 PyAPI_FUNC(int) _Py_convert_optional_to_ssize_t(PyObject *, void *);
 
-/* Same as PyNumber_Index but can return an instance of a subclass of int. */
+// Same as PyNumber_Index but can return an instance of a subclass of int.
+// Cannot be moved to the internal C API: used by Argument Clinic.
 PyAPI_FUNC(PyObject *) _PyNumber_Index(PyObject *o);
diff --git a/Include/internal/pycore_abstract.h b/Include/internal/pycore_abstract.h
index 9ba2748..2733d81 100644
--- a/Include/internal/pycore_abstract.h
+++ b/Include/internal/pycore_abstract.h
@@ -41,6 +41,13 @@ extern int _PyObject_HasLen(PyObject *o);
 extern Py_ssize_t _PySequence_IterSearch(PyObject *seq,
                                          PyObject *obj, int operation);
 
+/* === Mapping protocol ================================================= */
+
+extern int _PyObject_RealIsInstance(PyObject *inst, PyObject *cls);
+
+extern int _PyObject_RealIsSubclass(PyObject *derived, PyObject *cls);
+
+
 #ifdef __cplusplus
 }
 #endif