clang -O2 -Wall -Wextra -Werror=implicit-function-declaration uchar/mbrtoc32.c -o uchar/mbrtoc32 -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lintl uchar/mbrtoc32.c:4:10: fatal error: 'uchar.h' file not found #include ^ 1 error generated.