There is a use of external inline function in zookeeper hashtable_itr.h file, which is not compatible with C99. This causes problem when compiling with other library like code coverage library.
hashtable_itr.h:37: error: 'cov_v_cab2c78b' is static but used in inline
function 'hashtable_iterator_key' which is not static
The easy fix would be put the following line in hashtable_itr.c which ignores this inline warning.
#pragma GCC diagnostic ignored "-Winline"