clang -O2  -Wall -Wextra -Werror=implicit-function-declaration semaphore/sem_trywait.c -o semaphore/sem_trywait -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
../out/minix/basic/semaphore/sem_trywait.o: In function `main':
semaphore/sem_trywait.c:(.text+0x30e): undefined reference to `sem_init'
semaphore/sem_trywait.c:(.text+0x31a): undefined reference to `sem_trywait'
semaphore/sem_trywait.c:(.text+0x326): undefined reference to `sem_trywait'
semaphore/sem_trywait.c:(.text+0x332): undefined reference to `sem_trywait'
semaphore/sem_trywait.c:(.text+0x348): undefined reference to `sem_post'
semaphore/sem_trywait.c:(.text+0x354): undefined reference to `sem_trywait'
clang: error: linker command failed with exit code 1 (use -v to see invocation)