Command failed due to signal: Abort trap: 6

Question

Since Xcode 7 and Swift 2.0, I get the error above, like in the screenshot shown here:

Answer 1

To me what caused this error was:

I created a file to create extensions on UIView. Inside this file, I created a private protocol named Foo.

Then I made:

extension UIView: Foo

Removing the private from the protocol made the error go away.

I guess this is probably a bug. The compiler should warn us about the issue. The same way it warns us we can't add private conformances to types it should tell us that conformance should be using a "public/internal" protocol.