better debug info when arg::operator=() fails
diff --git a/include/pybind11/attr.h b/include/pybind11/attr.h
index cfa5090..15d5982 100644
--- a/include/pybind11/attr.h
+++ b/include/pybind11/attr.h
@@ -229,11 +229,21 @@
object o = object(detail::type_caster<typename detail::intrinsic_type<T>::type>::cast(
a.value, return_value_policy::automatic, handle()), false);
- if (!o)
- pybind11_fail("arg(): could not convert default keyword "
- "argument into a Python object (type not "
- "registered yet?)");
-
+ if (!o) {
+#if !defined(NDEBUG)
+ std::string descr(typeid(T).name());
+ detail::clean_type_id(descr);
+ if (r->class_)
+ descr += " in method of " + (std::string) r->class_.str();
+ pybind11_fail("arg(): could not convert default keyword argument "
+ "of type " + descr +
+ " into a Python object (type not registered yet?)");
+#else
+ pybind11_fail("arg(): could not convert default keyword argument "
+ "into a Python object (type not registered yet?). "
+ "Compile in debug mode for more information.");
+#endif
+ }
r->args.emplace_back(a.name, a.descr, o.release());
}
};