Swift Framework does not include symbols from extensions to generic structs

Question

I am having trouble linking my framework with code that takes advantage of that framework. Specifically, the linker isn\'t able to find the symbols for extensions for generi

Answer 1

In case you are looking for a temporary fix, you can wrap the extension in a class method:

// In your framework
public class OptionalOperator {
    public class func or<T>(optional:Optional<T>,defaultValue:T) ->T {
        return optional.or(defaultValue)
    }
}

// Outside the framework
var maybeText:String?
let text = OptionalOperator.or(maybeText, defaultValue: "Apple, please fix this")

Of course, this is not ideal and defeats the purpose of extensions. So if you plan on calling this method frequently, we could overload/define an operator.

// In your framework
infix operator ||| {}

public func |||<T>(left:Optional<T>, right:T) -> T {
    return left.or(right)
}

// Outside the framework
var maybeText:String?
let text = maybeText ||| "Apple, please fix this"

In my case, I have multiple applications using the framework, so I'd like to keep the method implementation inside the framework. However, overloading an operator (or just using a global function) would be awkward, so I have to go with the first option until that bug is fixed.

Hope this helps.

UPDATE

Funny thing is that Swift already has an operator for that (??).

var maybeText:String?
let text = maybeText ?? "Nice!"

It's called - Nil Coalescing Operator

Answer 2

I posted on the Apple Developer forums and an Apple employee responded that this is a known bug.

It looks like the compiler gets the mangled symbol names of methods in generic extensions wrong when they live in a different framework.