cc -pthread -Wall -Wextra quick_exit.c -o quick_exit -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lnetwork -lbsd -latomic quick_exit.c: In function 'main': quick_exit.c:9:9: warning: implicit declaration of function 'quick_exit' [-Wimplicit-function-declaration] 9 | quick_exit(0); | ^~~~~~~~~~ /boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/13.3.0/../../../../x86_64-unknown-haiku/bin/ld: ../out/haiku/basic/quick_exit.o: in function `main': quick_exit.c:(.text+0x8bc): undefined reference to `quick_exit' collect2: error: ld returned 1 exit status