While merging from master I noticed this warning:

src/mongoc/mongoc-stream.c: In function '_mongoc_stream_writev_full':
src/mongoc/mongoc-stream.c:493:23: warning: format '%ld' expects argument of type 'long int', but argument 5 has type 'long long int' [-Wformat=]
(long long)r, (unsigned long long)total_bytes, timeout_msec);
^
src/mongoc/mongoc-stream.c:493:23: warning: format '%ld' expects argument of type 'long int', but argument 6 has type 'long long unsigned int' [-Wformat=]