Function xmlSwitchInputEncoding 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn xmlSwitchInputEncoding(
    ctxt: *mut _xmlParserCtxt,
    input: *mut _xmlParserInput,
    handler: *mut _xmlCharEncodingHandler,
) -> c_int

Switch the encoding of a specific parser input using an encoding handler.

UPSTREAM-PARITY

int xmlSwitchInputEncoding(xmlParserCtxtPtr ctxt, xmlParserInputPtr input,
                           xmlCharEncodingHandlerPtr handler);

SAFETY

• ctxt, input, handler must be valid pointers (or NULL where the upstream C contract allows), obtained from the matching constructor/owner and not yet freed; the callee may take or keep ownership exactly as the C API specifies.

The caller must not race this call with concurrent mutation of the same objects from other threads (per-object state is not internally synchronized). Violating any of the above is undefined behavior.

Exercised by the C-API differential courts (courts/suites/data-abi/*-family-probe.c) and the CLI differential courts; those pass byte-for-byte against the upstream oracle.