Add hash constants (#85)

vstinner · web-flow · commit 7539c7f82c0e · 2024-03-09T22:14:47.000+01:00
diff --git a/docs/changelog.rst b/docs/changelog.rst
@@ -1,6 +1,13 @@
 Changelog
 =========
 
+* 2024-03-09: Add hash constants:
+
+  * ``PyHASH_BITS``
+  * ``PyHASH_IMAG``
+  * ``PyHASH_INF``
+  * ``PyHASH_MODULUS``
+
 * 2024-02-20: Add PyTime API:
 
   * ``PyTime_t`` type
diff --git a/pythoncapi_compat.h b/pythoncapi_compat.h
@@ -1196,6 +1196,18 @@ static inline int PyTime_PerfCounter(PyTime_t *result)
 
 #endif
 
+// gh-111389 added hash constants to Python 3.13.0a5. These constants were
+// added first as private macros to Python 3.4.0b1 and PyPy 7.3.9.
+#if (!defined(PyHASH_BITS) \
+     && ((!defined(PYPY_VERSION) && PY_VERSION_HEX >= 0x030400B1) \
+         || (defined(PYPY_VERSION) && PY_VERSION_HEX >= 0x03070000 \
+             && PYPY_VERSION_NUM >= 0x07090000)))
+#  define PyHASH_BITS _PyHASH_BITS
+#  define PyHASH_MODULUS _PyHASH_MODULUS
+#  define PyHASH_INF _PyHASH_INF
+#  define PyHASH_IMAG _PyHASH_IMAG
+#endif
+
 
 #ifdef __cplusplus
 }
diff --git a/tests/test_pythoncapi_compat_cext.c b/tests/test_pythoncapi_compat_cext.c
@@ -1522,6 +1522,20 @@ test_hash(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
     assert(Py_HashPointer(ptr1) == (Py_hash_t)ptr1);
 #endif
 
+#if ((!defined(PYPY_VERSION) && PY_VERSION_HEX >= 0x030400B1) \
+     || (defined(PYPY_VERSION) && PY_VERSION_HEX >= 0x03070000 \
+         && PYPY_VERSION_NUM >= 0x07090000))
+    // Just check that constants are available
+    size_t bits = PyHASH_BITS;
+    assert(bits >= 8);
+    size_t mod = PyHASH_MODULUS;
+    assert(mod >= 7);
+    size_t inf = PyHASH_INF;
+    assert(inf != 0);
+    size_t imag = PyHASH_IMAG;
+    assert(imag != 0);
+#endif
+
     Py_RETURN_NONE;
 }
 
