Thou shalt have no other gods before the ANSI C standard 1601

David Wagner ... snip ...

But this is precisely what is already feasible (and done) in Pascal and Ada, where it is possible to declare sub-range types. As ever, the programmer can foul these protections by misdeclaring his-her variables.

Now you are limiting yourself to a known unsafe language, C. I fail to understand why people indulge in the Quixotian sport of fixing C, when other languages without the defects already exist. Let's leave C its primary job - being a portable universal buttembler.

I believe Ada won't allow in-out parameters to a function, avoiding this problem (with the return value) entirely at a minimal cost. I won't fuss about the arbitrary creation of pointers here, because you can get the same effect with VAR parameters in Pascal. Of more practical interest would be (in a suitable language):

void f(int *p, int *q) { *p = 5; *q = 7; * further games * }

where the aliasing could have serious effects on further games.

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