Add _Py_Borrow() and _Py_XBorrow()

vstinner · vstinner · commit 73220fb57067 · 2020-12-01T13:48:37.000+01:00
diff --git a/README.rst b/README.rst
@@ -38,6 +38,8 @@ Python 3.10
 
     PyObject* Py_NewRef(PyObject *obj);
     PyObject* Py_XNewRef(PyObject *obj);
+    PyObject* Py_Borrow(PyObject *obj);
+    PyObject* Py_XBorrow(PyObject *obj);
 
 Python 3.9
 ----------
diff --git a/pythoncapi_compat.h b/pythoncapi_compat.h
@@ -32,6 +32,20 @@ static inline PyObject* Py_XNewRef(PyObject *obj)
 #endif
 
 
+// bpo-42522
+static inline PyObject* _Py_Borrow(PyObject *obj)
+{
+    Py_DECREF(obj);
+    return obj;
+}
+
+static inline PyObject* _Py_XBorrow(PyObject *obj)
+{
+    Py_XDECREF(obj);
+    return obj;
+}
+
+
 // bpo-39573: Py_TYPE(), Py_REFCNT() and Py_SIZE() can no longer be used
 // as l-value in Python 3.10.
 #if PY_VERSION_HEX < 0x030900A4
diff --git a/tests/test_pythoncapi_compat.c b/tests/test_pythoncapi_compat.c
@@ -39,6 +39,18 @@ test_object(PyObject *self, PyObject *ignored)
     int is_type = Py_IS_TYPE(obj, Py_TYPE(obj));
     assert(is_type);
 
+    // test _Py_Borrow()
+    Py_INCREF(obj);
+    PyObject *borrowed = _Py_Borrow(obj);
+    assert(borrowed == obj);
+    assert(Py_REFCNT(obj) == refcnt);
+
+    // test _Py_XBorrow()
+    Py_INCREF(obj);
+    PyObject *xborrowed = _Py_XBorrow(obj);
+    assert(xborrowed == obj);
+    assert(Py_REFCNT(obj) == refcnt);
+
     Py_DECREF(obj);
     Py_RETURN_NONE;
 }
