Is there a way in sbt to convert compiler warnings to errors so the build fails?

Question

I want to "ban" some or all compiler warnings.

Answer 1

You can pass options from sbt to the scala compiler, including the one that turns warnings into errors.

I usually add these:

scalacOptions ++= Seq("-unchecked", "-deprecation", "-feature", "-Xfatal-warnings"),

Answer 2

Per the scalac options documentation, you can pass either -Werror or -Xfatal-warnings.
You can do that in sbt by appending to scalacOptions.

scalacOptions += "-Werror"