Deriving a complex-type-with-simple-content by restriction
The Saxon schema processor (under circumstances that have not been pinned down precisely) produces a spurious error message saying that a complex type with simple content cannot be derived by restriction from a simple type.
In the case in question, the c-t-with-s-c in question is derived by restriction, and its content type (the type of its simple content) is properly derived by restriction from the content type of its base type.
A patch has been developed that simply involves removing the check that generates this error message. This doesn't cause any other tests to fail, so it seems that the check is spurious. The patch is being committed to the 9.4 branch.
A curiosity worth noting, which has not been explained, is that the failure does not occur under 9.3, although the code in question has not been changed.