clang -O2  -Wall -Wextra -Werror=implicit-function-declaration unistd/confstr.c -o unistd/confstr -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
../out/minix/basic/unistd/confstr.o: In function `main':
unistd/confstr.c:(.text+0x30f): undefined reference to `confstr'
unistd/confstr.c:(.text+0x335): undefined reference to `confstr'
clang: error: linker command failed with exit code 1 (use -v to see invocation)