PyString_AsString is permissive and accepts unicode strings.
Replace it with PyUnicode_AsString when the argument is known to be a str.
diff --git a/Objects/setobject.c b/Objects/setobject.c
index f6ea441..d85a28d 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -2303,7 +2303,7 @@
/* Exercise direct iteration */
i = 0, count = 0;
while (_PySet_Next((PyObject *)dup, &i, &x)) {
- s = PyString_AsString(x);
+ s = PyUnicode_AsString(x);
assert(s && (s[0] == 'a' || s[0] == 'b' || s[0] == 'c'));
count++;
}