Function xsltRegisterExtFunction 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn xsltRegisterExtFunction(
    ctxt: *mut _xsltTransformContext,
    name: *const xmlChar,
    NS_uri: *const xmlChar,
    f: Option<unsafe extern "C" fn(*mut c_void, c_int)>,
) -> c_int

Register an XSLT extension function.

SAFETY

• ctxt must be a valid _xsltTransformContext.
• name and NS_uri must be valid NUL-terminated strings.
• f must be a valid function pointer.