How to "re-run with -deprecation for details" in sbt? - sbt

Question

When I compile Scala code, by running sbt compile, SBT says:
$ sbt compile
...
[warn] there were 5 deprecation warnings; re-run with -deprecation for details
...
How do I do that? (From within SBT?)

Answer 1

sbt shell
While in sbt shell (if you don't want to change your build.sbt):
$ sbt
> set ThisBuild/scalacOptions ++= Seq("-unchecked", "-deprecation")
> compile
> exit
Due to in ThisBuild, set applies the settings to all sub-projects, as well.
Command Line
You could also run the above as a single command on command line.
sbt '; set ThisBuild/scalacOptions ++= Seq("-unchecked", "-deprecation") ; compile'
The trick is to use ; (semicolons) to separate commands and ' (ticks) to include all ;-separated commands as a single argument to sbt.
sbt < 1.x
Instead of ThisBuild/scalacOptions use scalacOptions in ThisBuild

Answer 2

scalacOptions := Seq("-unchecked", "-deprecation")
Add this setting to your build.sbt, and, if you have a multi-module project, add it to every project's settings.

Answer 3

As times flows new solutions are emerged. So, now you could re-run the scala compiler without issuing entire project rebuild.
You need to install ensime-sbt plugin:
addSbtPlugin("org.ensime" % "sbt-ensime" % "1.0.0")
After that you could use the ensimeCompileOnly task to compile single file. SBT allows per tasks settings configuration, so you could change for that tasks only:
set scalacOptions in (Compile, EnsimeKeys.ensimeCompileOnly) += "-deprecation"
ensimeCompileOnly src/main/scala/MyFile.scala