Document scalacOptions for sbt-scalafix and explicitReturnTypes config

[MasseGuillaume]

Hey Olaf,

I tried to run scalafmt on the scaladex codebase. This is how it's configured:

scalacenter/scaladex@f8dabd5

The doc has mentioned I should configure this rewrite https://scalacenter.github.io/scalafix/#ExplicitReturnTypes

[MasseGuillaume]

I think the solution is to do this:

x.explicitReturnTypes {
   memberKind = [
     Def
     Var
     Val
   ]
   memberVisibility = [
     Public
     Protected 
  ]
}

[MasseGuillaume]

Also, unrelated to this issue. I ran RemoveUnusedImports. I see some unused import warning from the compiler, but they are not removed by scalafix.

[olafurpg]

I managed to reproduce your issue and the problem was that build.sbt sets scalacOptions := instead of ++=. By replacing := with ++= I was able to run the rewrites. Alternatively, the next release of sbt-scalafix exposes a scalafixScalacOptions setting which can be appended to scalacOptions if you prefer to keep :=. This is not documented so I'm gonna keep this issue open.