Implicit conversion with auto constructors

[GetSwifty]

See the as-operator-overload thread for related discussion. Specifically:

@Ben_Cohen

It is unlikely the core team will consider a proposal to allow customization of the behavior of as on different types.

The best way to think of the as keyword is as a way to provide "type context". That is, the following things should be seen as equivalent:

let x = foo as Bar
let y: Bar = foo

The benefit of as being it's a lot more versatile than assigning to a variable i.e. you can do this:

// f can take any type
func f<T>(_ t: T) { ... }
// fix T to be of type Bar, not type Foo
f(foo as Bar)

...without having to create a temporary. But it's best not to think of the as is an operator doing the conversion. Rather the conversion happens because the compiler is willing to convert certain types to other types implicitly, and the as is a way of spelling out the types in question. But typed variable declarations or function arguments are another way.