When building jdk/jdk with gcc 7.3.1 (with warnings as errors disabled) we run into this issue :

/open_jdk/jdk_just_clone/jdk/src/hotspot/share/opto/parse2.cpp:1349:14: note: ‘sprintf’ output 2 or more bytes (assuming 2147488583) into a destination of size 30
       sprintf(prob_str_buf, "%g", prob);
       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
cc1plus: all warnings being treated as errors