$ sbt compile [warn] there were 6 deprecation warnings; re-run with -deprecation for details [warn] there were 4 feature warnings; re-run with -feature for details
How do I “re-run with -deprecation” or “re-run with -feature”?
Add a line like this to your build.sbt file to see the deprecation and feature warning messages:
scalacOptions ++= Seq("-deprecation", "-feature")
If you just want to add one setting, you don’t need a
Seq, just use this syntax:
scalacOptions += "-deprecation"
If you don’t want to modify your build.sbt file and just want this in your current SBT session, run this command from the SBT command line to get the same effect:
sbt> set scalacOptions in ThisBuild ++= Seq("-deprecation", "-feature")
You can find more answers to questions like this in the Scala Cookbook.