OS X 10.11 15A204h. Xcode 6.4 has a white slash through the icon. When I try to run it, I get this:
In order to open "Xcode", you need to update to the latest version.
The version of Xcode installed on this Mac is not compatible with OS X El Capitan. You have "Xcode" 6.4. Download version 6.4 for free from the Mac App Store.
I'm guessing I need a newer version of Xcode, and the error message is wrong?