"gcc -o conftest -I/usr/include/x86_64-linux-gnu/ruby-2.5.0 -I/usr/include/ruby-2.5.0/ruby/backward -I/usr/include/ruby-2.5.0 -I. -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -fPIC conftest.c -L. -L/usr/lib/x86_64-linux-gnu -L. -Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -fstack-protector -rdynamic -Wl,-export-dynamic -lruby-2.5 -lpthread -lgmp -ldl -lcrypt -lm -lc" /usr/lib/ruby/2.5.0/mkmf.rb:395: warning: Insecure world writable dir /mnt/c in PATH, mode 040777 checked program was: /* begin */ 1: #include "ruby.h" 2: 3: int main(int argc, char **argv) 4: { 5: return 0; 6: } /* end */