Mention type in the exception message.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 9dc96da..a0740db 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -3528,8 +3528,9 @@
return x;
else {
/* wrong return value */
- PyErr_SetString(PyExc_TypeError,
- "character mapping must return integer, None or str");
+ PyErr_Format(PyExc_TypeError,
+ "character mapping must return integer, None or str8, not %.400s",
+ x->ob_type->tp_name);
Py_DECREF(x);
return NULL;
}