在Swift中使用Where Clauses时出现错误

Question

我在使用Where子句和Swift时遇到错误，但我不知道如何解决它，代码和错误如下所示。

struct Stack<T>: Container {

    // original Stack<T> implementation

    var items = T[]()

    mutating func push(item: T) {
        items.append(item)
    }

    mutating func pop() -> T {
        return items.removeLast()
    }

    // conformance to the Container protocol

    mutating func append(item: T) {
        self.push(item)
    }

    var count: Int {
        return items.count
    }

    subscript(i: Int) -> T {
        return items[i]
    }
} 

********************************************************************************
func allItemsMatch<C1: Container, C2: Container
    where C1.ItemType == C2.ItemType, C1.ItemType: Equatable>
    (someContainer: C1, anotherContainer: C2) -> Bool {

        // check that both containers contain the same number of items

        if someContainer.count != anotherContainer.count {
            return false
        }

        // check each pair of items to see if they are equivalent

        for i in 0..someContainer.count {
            if someContainer[i] != anotherContainer[i] {
                return false
            }
        }

        // all items match, so return true
        return true
}

*****************************************************************************************
var stackStrings = Stack<String>()
stackOfStrings.push("uno")
stackOfStrings.push("dos")
stackOfStrings.push("tres")

var arrayOfStrings = ["uno", "dos", "tres"]

//I got the error from the following line of code

//(Swift Compiler Error: Cannot convert the expression's type 'Bool' to type '@lvalue Array')

if allItemsMatch(stackStrings, arrayOfStrings) {   
    println("All items match.")
} else {
    println("Not all items match.")
}

非常感谢任何帮助或建议。