the executable that should be built by $cmd doesn't get built. The object file gets created, but that's as far as it gets.
This stuff is unbelievably buggy. Stuff that works in a demo script fails when applied to the 00_ptr_cast test script. And it's a bloody pain - I have to close the console and open up a new one so I can delete the test executable (on those occasions where the test executable actually gets built).