Declarations in extensions cannot override yet - Swift 4

[lusabo]

When I tried to migrate my app to use Xcode 9 + Swift 4 I received the error Declarations in extensions cannot override yet in the files: Box.swift, Formatter.swift and Foundation.swift.

Example:

In the file Box.swift in the code below occurs the error in the line: open override var mustacheBox: MustacheBox {.

/// GRMustache provides built-in support for rendering `NSNull`.
extension NSNull {
   
   open override var mustacheBox: MustacheBox {
        return MustacheBox(
            value: self,
            boolValue: false,
            render: { (info: RenderingInfo) in return Rendering("") })
    }
}

How to solve?

Thanks,
Luciano

[lusabo]

I create a blank project and install the GRMustache and continuous giving the error Declarations in extensions cannot override yet

[hamedmohammadi]

you can go in pod project select GRMustache and change compiling swift to swift3.4 and everything work .
this project need to support swift 4 but doesn't yet

[EMart86]

I've seen a PR with swift4 compatibility has been merged 28 days ago. Any chance that this is merged on master and pushed as pod soon?

[yurkins]

same issue :(