In most of my courses that did something like this there was no resubmission.* The professor supplied a driver program, sample input the driver would use to test your program, expected output, and a Makefile template that gave you the 3 compilers + their flags that your program was expected to compile against and execute without issue. His server would do the compile-and-run for all 3 against the sample input and against hidden input revealed with the grade. He used the same compiler versions as were on the school lab computers.
* As a potentially amusing aside, a different course in a different degree program had a professor rage-quit after his first semester because he didn't want to deal with children -- he had a policy of giving 0s on papers with no name or class info on them, and enough students ("children") failed to do that correctly but complained hard enough to overturn the policy and get a resubmit.
* As a potentially amusing aside, a different course in a different degree program had a professor rage-quit after his first semester because he didn't want to deal with children -- he had a policy of giving 0s on papers with no name or class info on them, and enough students ("children") failed to do that correctly but complained hard enough to overturn the policy and get a resubmit.