compile.log

test.c:10:27: warning: incompatible pointer types passing 'jmp_buf' (aka 'struct __jmp_buf_tag [1]') to parameter of type 'void **' [-Wincompatible-pointer-types]
  (void)(__builtin_setjmp(tag.buf) ? 1 : 0);
                          ^~~~~~~
1 warning generated.
/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.3/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
/tmp/test-11ca81.o: In function `jump':
test.c:(.text+0x26): undefined reference to `.LBB0_-1'
clang: error: linker command failed with exit code 1 (use -v to see invocation)