Check for a common user error with defaultdict().
diff --git a/Modules/collectionsmodule.c b/Modules/collectionsmodule.c
index a4cdcfa..f98bd49 100644
--- a/Modules/collectionsmodule.c
+++ b/Modules/collectionsmodule.c
@@ -1252,8 +1252,14 @@
newargs = PyTuple_New(0);
else {
Py_ssize_t n = PyTuple_GET_SIZE(args);
- if (n > 0)
+ if (n > 0) {
newdefault = PyTuple_GET_ITEM(args, 0);
+ if (!PyCallable_Check(newdefault)) {
+ PyErr_SetString(PyExc_TypeError,
+ "first argument must be callable");
+ return -1;
+ }
+ }
newargs = PySequence_GetSlice(args, 1, n);
}
if (newargs == NULL)