is there an annotation we can use to mark debug-statements or something, so i get a warning during compile time if there are debug statements in my code left?

You can use

//STOPSHIP

after making it fatal in options

android {
  lintOptions {
      fatal 'StopShip'
  }
}

but that only works for android,, doesnt it?

I create

//TODO

coment and then have IntelliJ setup to warn me before commit if there are any TODOs left in code

Mark the functions deprecated with a warning that it's for debugging purposes only. If the debug code is not in a function, wrap it in a function (potentially passing a closure for custom debug code).

thank you - i asked in #kapt, too, about how to add a compiler warning. but amrking it deprecated is a good idea, too 🙂