When a PyCFunction that takes only positional parameters is called with

an empty keywords dictionary (via apply() or the extended call syntax),
the keywords dict should be ignored.  If the keywords dict is not empty,
TypeError should be raised.  (Between the restructuring of the call
machinery and this patch, an empty dict in this situation would trigger
a SystemError via PyErr_BadInternalCall().)

Added regression tests to detect errors for this.

1 files changed, 19 insertions, 18 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index dd626e5f88..1559456e6b 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2607,23 +2607,30 @@ call_cfunction(PyObject *func, PyObject *arg, PyObject *kw)
 	PyObject *self = PyCFunction_GET_SELF(func);
 	int flags = PyCFunction_GET_FLAGS(func);
 
-	if (flags & METH_KEYWORDS && kw == NULL) {
-		static PyObject *dict = NULL;
-		if (dict == NULL) {
-			dict = PyDict_New();
-			if (dict == NULL)
-				return NULL;
+	if (flags & METH_KEYWORDS) {
+		if (kw == NULL) {
+			static PyObject *dict = NULL;
+			if (dict == NULL) {
+				dict = PyDict_New();
+				if (dict == NULL)
+					return NULL;
+			}
+			kw = dict;
+			Py_INCREF(dict);
 		}
-		kw = dict;
-		Py_INCREF(dict);
+		return (*(PyCFunctionWithKeywords)meth)(self, arg, kw);
 	}
-	if (flags & METH_VARARGS && kw == NULL) {
-		return (*meth)(self, arg);
+	if (kw != NULL && PyDict_Size(kw) != 0) {
+		PyErr_Format(PyExc_TypeError,
+			     "%.200s() takes no keyword arguments",
+			     f->m_ml->ml_name);
+		return NULL;
 	}
-	if (flags & METH_KEYWORDS) {
-		return (*(PyCFunctionWithKeywords)meth)(self, arg, kw);
+	if (flags & METH_VARARGS) {
+		return (*meth)(self, arg);
 	}
 	if (!(flags & METH_VARARGS)) {
+		/* the really old style */
 		int size = PyTuple_GET_SIZE(arg);
 		if (size == 1)
 			arg = PyTuple_GET_ITEM(arg, 0);
@@ -2631,12 +2638,6 @@ call_cfunction(PyObject *func, PyObject *arg, PyObject *kw)
 			arg = NULL;
 		return (*meth)(self, arg);
 	}
-	if (kw != NULL && PyDict_Size(kw) != 0) {
-		PyErr_Format(PyExc_TypeError,
-			     "%.200s() takes no keyword arguments",
-			     f->m_ml->ml_name);
-		return NULL;
-	}
 	/* should never get here ??? */
 	PyErr_BadInternalCall();
 	return NULL;