How to failed compilation if there are any dead code or unused imports, variables etc

Question

I am trying to failed compilation if there are any unused imports, local or private variables or dead code in the codebase. So, I have added following scalacoptions.

scalacOptions ++= Seq(
        "-encoding", "UTF-8",
        "-Xfatal-warnings",
        "-Xlint:-unused,_",
        "-Ywarn-dead-code",
        "-Ywarn-unused:imports",             // Warn if an import selector is not referenced
        "-Ywarn-unused:locals",              // Warn if a local definition is unused
        "-Ywarn-unused:patvars",             // Warn if a variable bound in a pattern is unused
        "-Ywarn-unused:privates",            // Warn if a private member is unused
        "-deprecation"
      )

But whenever I compile my project, it fails compilation and gives the following error.

[error] 'imports' is not a valid choice for '-Ywarn-unused'
[error] bad option: '-Ywarn-unused:imports'

scala version: 2.11.11

I am not sure what mistake i am doing.

You probably mean an analogous error, something like `bad option: '-Ywarn-unused-import'`? — Andrey Tyukin, Mar 08 '19 at 17:05
I think -Ywarn-unused:imports is valid only for scala 2.12. please verify whether it is valid for 2.11 — user51, Mar 08 '19 at 17:05
@rajkumar natarajan if it is only supported with 2.12. is there any way to do same with Scala version 2.11? — Mahesh Chand, Mar 08 '19 at 17:07
@MaheshChandKandpal - Good question. I see here the valid args for scalac 2.11 https://github.com/scala/scala/blob/v2.11.12/src/compiler/scala/tools/nsc/settings/Warnings.scala. — user51, Mar 08 '19 at 17:10
If you have a `scalac` version 2.11.11 around, you could let it list the relevant options with `scalac -Y | grep import` in the console (assuming bash / *nix environment). — Andrey Tyukin, Mar 08 '19 at 17:12
@RajkumarNatarajan I saw that too but it didn't fail compilation. It gives warning. — Mahesh Chand, Mar 11 '19 at 05:32

score 1 · Answer 1 · answered Apr 10 '19 at 07:34

Below settings should work -

    lazy val project_name = project.in(file(".")).settings(commonSettings)

    lazy val commonSettings = reformatOnCompileSettings ++ Seq(
    scalacOptions ++= Seq(
        "-Ywarn-unused-import",
        "-language:postfixOps",
        "-Ypartial-unification"
    )
    )

Hope this helps.

How to failed compilation if there are any dead code or unused imports, variables etc

1 Answers1