Function validate_one_element 

pub unsafe fn validate_one_element(
    ctxt: *mut _xmlValidCtxt,
    doc: *mut _xmlDoc,
    elem: *mut _xmlNode,
) -> c_int

Upstream xmlValidateOneElement(ctxt, doc, elem) — validates a single element against its declaration (content model + attributes), WITHOUT recursing into children.

SAFETY

• ctxt may be NULL; doc/elem valid pointers or NULL.