[swift-evolution] [Manifesto] Completing Generics

[Joe Groff]

> On Mar 10, 2016, at 1:34 PM, Howard Lovatt <howard.lovatt at gmail.com> wrote:
> 
> @Thorsten,
> 
> No it doesn't, the following Java code:
> 
> public class GenericReturnTypes {
>   interface Foo {
>     static <Output extends Number> Output foo() {
>       return (Output)(new Integer(0));
>     }
>   }
>   public static void main(String[] args) {
>     System.out.println(Foo.foo());
>   }
> }
>  
> Compiles without error or warning, runs, and prints 0.

This works by inferring Output == Number. This also unsafely allows 'Float foo = Foo.foo();', which would fail the cast.

-Joe

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