Is Xcode9 compatible with Swift 3 (or 3.1)?

I just started using Xcode9 (beta2). I realized that this would not force me to immediately change my code. However, I am getting build errors with the library I am using (Gloss):

1) For the following code:

public func valueForKeyPath(keyPath: String, withDelimiter delimiter: String = GlossKeyPathDelimiter, logger: Logger = GlossLogger()) -> Any? {

      

        
        
        
      

    

I get:

The initializer 'init ()' is internal and cannot refer to the default argument value

2) For this code:

internal func flatMap<KeyPrime : Hashable, ValuePrime>(_ transform: (Key, Value) throws -> (KeyPrime, ValuePrime)?) rethrows -> [KeyPrime : ValuePrime] {
    return Dictionary<KeyPrime,ValuePrime>(elements: try flatMap({ (key, value) in
        return try transform(key, value)
    }))
}

      

        
        
        
      

    

I get:

The closure parameter tuple '(key: _, value: _)' does not support destructuring

Both of these did not cause problems with Xcode 8.3 / Swift 3.1.

I am using Xcode9 with no option to upgrade to Swift 4. There are several possibilities:

• There are several flags that need to be set to keep Swift 3.1 backward compatible.
• Xcode9 is in beta and just not completely ready
• Xcode9 will not be fully backward compatible with Swift 3.1

Thoughts?