On Thursday, 9 August 2018 at 10:37:36 UTC, Andrea Fontana wrote:
On Thursday, 9 August 2018 at 04:10:47 UTC, Nicholas Wilson
wrote:
The DIP makes the claim that:
* "[@noreturn] has the awkward result of a function
specifying it has a return type T, but never returns that
type". When it is deliberate (such as annotating a fatal error
function) the is almost exclusively `void` (I know of no
examples to the contrary).
Let's say we need to implement an interface with a int func();
member. We can mark it with @noreturn but we can't use TBottom
return type: we're going to break interface implementation.
Andrea
It will work, and why it will work requires some understanding of
bottom types. You can define the function as `TBottom func()` and
it should work, because `TBottom` is a subtype of `int`. In the
same way you can implement `ParentClass func()` as `SubClass
func()`, because `SubClass` is a subtype of `ParentClass`.
Similarly, you can assign values of `TBottom` to `int`, because
`TBottom` is a subtype of all types, but you cannot assign `int`
to `TBottom`, because `int` is not a subtype of `TBottom`.
