Function xmlTextReaderGetLastError 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn xmlTextReaderGetLastError(
    reader: *mut XmlTextReader,
) -> *const _xmlError

const xmlError *xmlTextReaderGetLastError(xmlTextReaderPtr reader) — pointer to the reader’s embedded _xmlError (upstream returns &reader->ctxt->lastError, which is always present while the reader exists; valid until the next error is collected).