[sixfiveotwo]

> void is the unit type. The fact that it is not constructible is a wart of the language, inherited from C. > A function returning bottom cannot return, yet void foo() {} can.

Or you could say it the other way, that it is the bottom type, and the fact that it can be used as the unit type for returned values is a wart of the language. Furthermore, void* isn't a pointer of the unit type, it's a type for pointers to undefined/unspecified value types.

[gpderetta]

nothing is gained by making void a proper bottom type. It would only break existing code. OTOH make void a proper unit type would be backward compatible and actually make the language simpler both from a specification point of view and in practical terms.

[sixfiveotwo]

I didn't mean that it should be made into a bottom type, even though it sort of looks like it on the surface.

I think the original idea was that void meant "unknown", not "empty" or "non-existent": It was all about whether values could be allocated or not (the wart mentioned above). A plain void variable cannot, but a void pointer can be allocated. For functions, they just reused the keyword to mean "no return value" or "no arguments".

[LegionMammal978]

A pointer to the bottom type would make even less sense as an interpretation for void *, since such a pointer couldn't possibly point to any initialized value.

[sixfiveotwo]

Sorry, I wasn't clear enough: I meant that void is not just a mix of the unit and bottom types, it is also in used for unspecified (unknown actually) types.