In os_posix.c/print_rlimit_info there are a handful of printouts of values returned from calls to getrlimit, and specifically the rlim_cur field of the rlimit struct. The type of the rlim_cur field is rlim_t, but the spec doesn't say which exact type rlim_t is based on (it just mentions that it's an unsigned integer type).

Depending on the platform and/or flags used when compiling the code, the rlim_t type may, for example, either be an unsigned long, or an unsigned long long. This means that it's not always correct to use the %lu format specifier when printing the value, and since the print calls are being verified this will turn into a build error if the format and argument types do not match.