Relationship between return value and garbage value

What happens if the return statement does not produce a return value in a function that produces a return value in C language? Does the compiler use garbage values in this case? Is this called undefined behavior?

For example;

#include <stdio.h>int func() {}int main() {    int result = func();    printf("Result: %d\n", result);    return 0;}

Output of this code :Result: 0

I am expecting this is a undefined behavior.