This is a silly example of course because you don't have to check free() for null; calling free(NULL) is a no-op. In a more realistic case, say some object was

This is a silly example of course because you don't have to check free() for null; calling free(NULL) is a no-op. In a more realistic case, say some object was handed off so it shouldn't be cleaned up anymore, you can just add a should_cleanup flag and check it in the defer block. There's really no need for guard. Their other example for guard, running defer in a loop, requires closures. This means it requires dynamic memory allocation and so the complexity goes through the roof.