Function xmlEncodeEntities 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn xmlEncodeEntities(
    _doc: *mut _xmlDoc,
    _input: *const xmlChar,
) -> *mut xmlChar

Deprecated entity encoder (upstream 2.15 xmlEncodeEntities): the symbol still exists for ABI compatibility but emits a one-time deprecation warning and returns NULL (verified against the oracle DSO disassembly — the 2.15 implementation returns NULL after warning).

UPSTREAM-PARITY

xmlChar *xmlEncodeEntities(xmlDocPtr doc, const xmlChar *input);