I suspect a compiler bug since A is a P. The equivalent in Java works:
interface P {}
class X implements P {}
<A extends P> void foo(A x) {}
void bar() {
final P x = new X();
foo(x);
}
-- Howard.
> On 23 Dec 2016, at 3:19 am, Rien via swift-users <swift-users@swift.org>
> wrote:
>
> IMO the error message says it all:
>
> Playground execution failed: error: MyPlayground8.playground:9:5: error:
> cannot invoke 'foo' with an argument list of type '(P)'
> foo(x)
> ^
>
> MyPlayground8.playground:9:5: note: expected an argument list of type '(A)'
> foo(x)
> ^
>
> I.e. you are passing in a protocol while the function is specified for a type.
> Said other way: On which data do you expect the protocol to operate?
>
> Regards,
> Rien
>
> Site: http://balancingrock.nl
> Blog: http://swiftrien.blogspot.com
> Github: http://github.com/Swiftrien
> Project: http://swiftfire.nl
>
>
>
>
>> On 22 Dec 2016, at 17:05, Mikhail Seriukov via swift-users
>> <swift-users@swift.org> wrote:
>>
>> Hello community! I' wondering if somebody can explain this to me.
>> Please take look at the snippet.
>>
>> protocol P {}
>> struct X:P {}
>>
>> func foo<A:P>(_ x:A) {}
>>
>> func bar() {
>> //let x = X() // this compiles
>> let x = X() as P // this does not compile. Why?
>> foo(x)
>> }
>>
>> I expect the both cases to work though. But only first works? And I do not
>> understand why.
>> My coworkers said that it is a compiler bug, but I'm not shure it is.
>> Thanks for the help.
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>> swift-users@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-users
>
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