Using C11 compiler, and a Makefile from a template, where the Makefile defines CFLAGS with -Werror I get:
.../components/libraries/util/app_error.c:47:5: error: narrowing conversion of 'line_num' from 'uint32_t {aka long unsigned int}' to 'uint16_t {aka short unsigned int}' inside { } is ill-formed in C++11 [-Werror=narrowing] };
It is not a bug unless someone has a source file with a gazillion lines? but it would be nice to use stronger error checking of C11 without turning off -Werrors.
If this is not the proper place to report this, please let me know.