A redefinition of an attributeGroup is a restriction of the original
(src-redefine / cos-ct-restricts), so a re-declared attribute's type must derive
by restriction from the original's. The attribute-restriction checks covered
drop-required, re-introduce-prohibited, add-attribute, and relax-fixed, but not a
type change that widens rather than restricts.
Add a built-in-only, namespace-gated check: it fires only when both the original
and the re-declared attribute name a built-in type resolving to the XSD namespace
and the re-declared built-in does not derive from the original's in the XSD
derivation lattice (int does not derive from boolean). A user, inline, or absent
type on either side is not compared, so the check declines and stays lenient: an
absent original type is anySimpleType (which any type restricts), a user/inline
type's derivation is not resolvable here, and a user type whose local name
coincides with a built-in resolves to a different namespace and is not mistaken
for the built-in.
This catches W3C XSTS schM4 (a redefinition re-typing an attribute from boolean
to int). XSTS schema invalid-accepted 24 -> 23, valid-rejected held at 0.
Mihaela Mihaljevic
b6e5cd8f3f