Add Py_HashPointer() (#83)

Author: vstinner

docs/api.rst

@@ -137,6 +137,10 @@ Python 3.13
 
    See `PyDict_PopString() documentation <https://docs.python.org/dev/c-api/dict.html#c.PyDict_PopString>`__.
 
+.. c:function:: Py_hash_t Py_HashPointer(const void *ptr)
+
+   See `Py_HashPointer() documentation <https://docs.python.org/dev/c-api/hash.html#c.Py_HashPointer>`__.
+
 
 Python 3.12
 -----------

docs/changelog.rst

@@ -1,6 +1,7 @@
 Changelog
 =========
 
+* 2023-12-15: Add function ``Py_HashPointer()``.
 * 2023-11-14: Add functions:
 
   * ``PyDict_Pop()``

pythoncapi_compat.h

@@ -1089,6 +1089,25 @@ PyDict_PopString(PyObject *dict, const char *key, PyObject **result)
 }
 #endif
 
+
+#if PY_VERSION_HEX < 0x030200A4
+// Python 3.2.0a4 added Py_hash_t type
+typedef Py_ssize_t Py_hash_t;
+#endif
+
+
+// gh-111545 added Py_HashPointer() to Python 3.13.0a3
+#if PY_VERSION_HEX < 0x030D00A3
+static inline Py_hash_t Py_HashPointer(const void *ptr)
+{
+#if PY_VERSION_HEX >= 0x030900A4 && !defined(PYPY_VERSION)
+    return _Py_HashPointer(ptr);
+#else
+    return _Py_HashPointer(_Py_CAST(void*, ptr));
+#endif
+}
+#endif
+
 #ifdef __cplusplus
 }
 #endif

tests/test_pythoncapi_compat_cext.c

@@ -1498,6 +1498,34 @@ test_list(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
 }
 
 
+static PyObject *
+test_hash(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
+{
+    void *ptr0 = NULL;
+    assert(Py_HashPointer(ptr0) == 0);
+
+#ifndef PYPY_VERSION
+#if SIZEOF_VOID_P == 8
+    void *ptr1 = (void*)(uintptr_t)0xABCDEF1234567890;
+    assert(Py_HashPointer(ptr1) == (uintptr_t)0x0ABCDEF123456789);
+#else
+    void *ptr1 = (void*)(uintptr_t)0xDEADCAFE;
+    assert(Py_HashPointer(ptr1) == (uintptr_t)0xEDEADCAF);
+#endif
+#else
+    // PyPy
+#if SIZEOF_VOID_P == 8
+    void *ptr1 = (void*)(uintptr_t)0xABCDEF1234567890;
+#else
+    void *ptr1 = (void*)(uintptr_t)0xDEADCAFE;
+#endif
+    assert(Py_HashPointer(ptr1) == (Py_hash_t)ptr1);
+#endif
+
+    Py_RETURN_NONE;
+}
+
+
 static struct PyMethodDef methods[] = {
     {"test_object", test_object, METH_NOARGS, _Py_NULL},
     {"test_py_is", test_py_is, METH_NOARGS, _Py_NULL},
@@ -1530,6 +1558,7 @@ static struct PyMethodDef methods[] = {
 #endif
     {"test_unicode", test_unicode, METH_NOARGS, _Py_NULL},
     {"test_list", test_list, METH_NOARGS, _Py_NULL},
+    {"test_hash", test_hash, METH_NOARGS, _Py_NULL},
     {_Py_NULL, _Py_NULL, 0, _Py_NULL}
 };