Open Radar

 
Summary:
A generic function that is declared to take a value that conforms to a protocol and the Type of the same protocol fails to take said arguments.
If I pass in a concrete struct that conforms, and that struct's dynamicType, no error is emitted.

Steps to Reproduce:
Compile the attached sample with Xcode 7.0 beta 4:

xcrun -sdk macosx swiftc -c struct-conforming-protocol-dynamic-type-as-type-argument.swift


Expected Results:
Seems like it should compile *or* it should fail in the case that `value` is typed as Value instead of ValueProtocol.


Actual Results:
The to() function fails to match the passed arguments, with the errors

struct-conforming-protocol-dynamic-type-as-type-argument.swift:34:1: error: cannot invoke 'to' with an argument list of type '(ValueProtocol, t: ValueProtocol.Type)'
to(value, t:value.dynamicType)
^
struct-conforming-protocol-dynamic-type-as-type-argument.swift:34:1: note: expected an argument list of type '(T, t: T.Type)'
to(value, t:value.dynamicType)
^

but this seems like they do match with T=ValueProtocol.


Version:
Xcode 7.0 b4

Notes:


Configuration:


Attachments:

/*

xcrun -sdk macosx swiftc -c struct-conforming-protocol-dynamic-type-as-type-argument.swift

This results in errors, even though the second argument is supposed to be of ValueProtocol.Type. If `value` is not typed to ValueProtocol (so it is inferred as Value), then no error is emitted.

struct-conforming-protocol-dynamic-type-as-type-argument.swift:34:1: error: cannot invoke 'to' with an argument list of type '(ValueProtocol, t: ValueProtocol.Type)'
to(value, t:value.dynamicType)
^
struct-conforming-protocol-dynamic-type-as-type-argument.swift:34:1: note: expected an argument list of type '(T, t: T.Type)'
to(value, t:value.dynamicType)
^

*/

public protocol ValueProtocol {
    var value:Double { get }
    init(_ value:Double)
}

public struct Value : ValueProtocol {
    public let value:Double
    public init(_ value:Double) {
        self.value = value
    }
}

public func to<T:ValueProtocol>(x:T, t: T.Type) -> T {
    return t.init(x.value)
}

let value:ValueProtocol = Value(10)

to(value, t:value.dynamicType)