bottom type as parameter or local variable, does that make sense?

Max Samukha maxsamukha at
Sun Jan 16 22:56:44 UTC 2022

On Saturday, 15 January 2022 at 18:35:02 UTC, Paul Backus wrote:
> Technically, a variable is a name associated with a block of 
> memory, which may or may not contain a value. In the case of 
> `noreturn`, the block of memory has size 0, and there are no 
> possible values it can contain.

Memory of size 0 contains a single value, which is the value of 
the unit type, 0-tuple, or whatever. Zero type is different. 
Timon, I am totally confused, could you clarify?

> So, technically, a `noreturn` variable is impossible to 
> initialize. But since the compiler knows that the behavior of 
> the program can't possibly depend on the variable's value, it 
> is free to just skip the initialization altogether and leave 
> the variable uninitialized instead.

Sounds like "alias x = noreturn.init;"

> I guess you could make an argument that you should have to 
> write `noreturn x = void;` every time you declare a `noreturn` 
> variable. But even then, it would not be correct for `noreturn 
> x;` to result in an `assert(0)` at runtime--it would have to be 
> a *compile-time* error.

I think it depends on the definition of local declaration. For 
statics, it is obviously a compile-time error. For locals, my 
feeling is it should be a runtime error, but who knows. Timon, 

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