Why c cannot understand (- 1 < 0) is true

Question

I made program that evaluated to this at some point:
int64_t m=-1, z=0;
if(m<z) {/*not evaluated */}
//GNU c compiler
Why it cannot compare two ints?

Answer 1

Did you include <stdint h>?
Was there any error message?
Have you tried putting a simple printf() call in conditional body just in case?