Make Xcode use sourcekitd in custom toolchain

That is very surprising. I haven’t heard any similar reports before and don’t see the issue either. Some more ideas/questions:

  • What do you have set in System Preferences -> Security & Privacy -> General -> Allow apps downloaded from. I suspect that this needs to be “App Store and identified developers”
  • Is this on an Intel Mac or Apple Silicon machine?
  • Which Xcode and macOS version are you using?