Cross- compilation assumes that a compiler for language X exists on some machine. When the first compiler for a new language is created, this assumption doesn't hold. In this situation, a bootstrapping approach can be taken. First, a subset of language X is chosen that is sufficient to implement a simple compiler. Next, a simple compiler for the X subset is written in any available language. This compiler must be correct, but it should not be any more elaborate than is necessary, since it will soon be discarded. Next, the subset compiler for X is rewritten in the X subset and then compiled using the subset compiler previously created. Finally, the X subset, and its compiler, can be enhanced until a complete compiler for X, written in X, is available. Assume you are bootstrapping C++ or Java (or some comparable language). Outline a suitable subset language. What language features must be in the language? What other features are desirable?