I've found that xmlStrPrintf prototype has changed in 2.9.3

from 

XMLPUBFUN int XMLCALL
                xmlStrPrintf             (xmlChar *buf,
                                         int len,
                                         const xmlChar *msg,
                                         ...);

to

XMLPUBFUN int XMLCALL
                xmlStrPrintf             (xmlChar *buf,
                                         int len,
                                         const char *msg,
                                         ...) LIBXML_ATTR_FORMAT(3,4);


I wanted to use LIBXML_VERSION to distinguish old and new prototypes to correctly cast in my code.

But suddenly I found one platform (OpenWRT) where 2.9.3 still have the old prototype.

Please suggest what to use during C preprocessor to test if the new prototype should be used.

BTW, it is a bad idea to change function prototype ;(