optimise dict.clear()

--HG--
extra : rebase_source : afba300a108428a9e515a63a822d62cced8e2e05

Cython/Compiler/Builtin.py

@@ -240,6 +240,15 @@ static PyObject* __Pyx_Intern(PyObject* s) {
 }
 ''')
 
+py_dict_clear_utility_code = UtilityCode(
+proto = '''
+static CYTHON_INLINE PyObject* __Pyx_PyDict_Clear(PyObject* d) {
+    PyDict_Clear(d);
+    Py_INCREF(Py_None);
+    return Py_None;
+}
+''')
+
 py_set_utility_code = UtilityCode(
 proto = """
 #if PY_VERSION_HEX < 0x02050000
@@ -495,6 +504,8 @@ builtin_types_table = [
     ("dict",    "PyDict_Type",     [BuiltinMethod("items", "T",   "O", "PyDict_Items"),  # FIXME: Py3 mode?
                                     BuiltinMethod("keys",  "T",   "O", "PyDict_Keys"),   # FIXME: Py3 mode?
                                     BuiltinMethod("values","T",   "O", "PyDict_Values"), # FIXME: Py3 mode?
+                                    BuiltinMethod("clear", "T",   "O", "__Pyx_PyDict_Clear",
+                                                  utility_code = py_dict_clear_utility_code),
                                     BuiltinMethod("copy",  "T",   "T", "PyDict_Copy")]),
 
     ("slice",   "PySlice_Type",    [BuiltinAttribute('start'),

tests/run/builtin_methods_return_values.pyx

@@ -87,3 +87,11 @@ def set_add(set s):
     """
     s.add(1)
     return s.add(2)
+
+def dict_clear(dict d):
+    """
+    >>> dict_clear({1:2,3:4}) is None
+    True
+    """
+    d.clear()
+    return d.clear()