[zzo38computer]

What I would have it to do is: Return a number that is in the range of the "int" type, but there is no guarantee what number it will be, and it will not necessarily be consistent when called more than once, when the program is executed more than once (unless the operating system has features to enforce consistent behaviour), when the program is compiled for and running on a different computer, etc. I would also have the undefined value to be frozen, like the "freeze" command in LLVM. Normally, the effect would be according to the target instruction set, because it would be compiled in the best way for that target instruction set. Depending on the compiler options, it might also display a warning that not all cases are handled, although this warning would be disabled by default. (However, some instruction sets might allow it to be handled differently; e.g. if you have an instruction set with tagged pointers that can be stored in ordinary registers and memory, then there is the possibility that trying to use the return value causes an error condition.)