Ubuntu has another pedantic C99 warning:
mongoc/mongoc-uri.c: In function ‘mongoc_uri_parse_option’:
mongoc/mongoc-uri.c:765:10: warning: ISO C does not support %n$ operand number formats [-Wformat=]
MONGOC_WARNING ("Deprecated boolean value for \"%1$s\": \"%2$s\", "
^
mongoc/mongoc-uri.c:774:10: warning: ISO C does not support %n$ operand number formats [-Wformat=]
MONGOC_WARNING ("Deprecated boolean value for \"%1$s\": \"%2$s\", "
^