Yeah I saw a post on LinkedIn (can't find it again sorry) where they found that CCC compiles C by mostly just ignoring errors. `const` is a nop. It doesn't care if you redefine variables with different types, use a string where an `int` is expected, etc.

Whenever I've done optimisation (e.g. genetic algorithms / simulated annealing) before you always have to be super careful about your objective function because the optimisation will always come up with some sneaky lazy way to satisfy it that you didn't think of. I guess this is similar - their objective was to compile valid C code and pass some tests. They totally forgot about not compiling invalid code.