Unused import warning in routes (Play 2.6.0-RC1 and Scala 2.12.2)

[maxcom]

Play Version (2.5.x / etc)

2.6.0-RC1

API (Scala / Java / Neither / Both)

Scala

Expected Behavior

Play-2.6.0-RC1 project can be compiled with "-Xfatal-warnings" compiler option and Scala 2.12.2.

Actual Behavior

[error] /home/maxcom/git-checkout/abook-daemon/conf/routes: Unused import
[error] /home/maxcom/git-checkout/abook-daemon/conf/routes: Unused import
[error] /home/maxcom/git-checkout/abook-daemon/conf/routes: Unused import
[error] three errors found
[error] (compile:compileIncremental) Compilation failed
[error] Total time: 20 s, completed 24.05.2017 12:19:33

I think that unused import is

import _root_.controllers.Assets.Asset

in generated Routes and ReverseRoutes

[marcospereira]

Hey @maxcom,

If you are not using Assets controller, you can remove the import by adding the following lines to your build.sbt file:

import play.sbt.routes.RoutesKeys
RoutesKeys.routesImport := Seq.empty

Can you confirm that using this configuration fixes the problem for you? _root_.controllers.Assets.Asset is being imported because it is part of the default configuration, as you can see here:

playframework/framework/src/sbt-plugin/src/main/scala/play/sbt/PlaySettings.scala

Line 134 in 927fb83

RoutesKeys.routesImport ++= Seq("controllers.Assets.Asset"),

Thanks.

[maxcom]

Thanx, I used

RoutesKeys.routesImport -= "controllers.Assets.Asset"

That did reduce number of warnings, but did not solve all of them.

[maxcom]

Other unused imports are

import _root_.utils.Binders._

in ReverseRoutes.scala. We actually use reverse routes and we use binders in routes.

[marcospereira]

Thanks for the feedback, @maxcom.

Is Binders part of your application code, right? Maybe we should have more specific configurations for ReverseRouter and JavascriptReverseRouter.

WDYT?

[maxcom]

I'm not sure that it will help. Reverse routes is not the one file, but it is generated for each individual package. Some controllers uses only base types, some uses custom types and Options.

Maybe there is the way to disable this warnings for generated files only?

[gmalouf]

I just want to chime in I am seeing what I believe is the same warning except in my template files:

scala 2.12.4
play 2.6.7

@(elements: helper.FieldElements)

<div class="form-group checkbox-group @if(elements.hasErrors) {error}">
    @elements.input
    <label for="@elements.id" class="checkbox">@elements.label</label>
    <span class="errors">@elements.errors.mkString(", ")</span>
</div>

[warn] /Users/gary/AdAgility/coriander/app/com/offerlogic/coriander/infrastructure/display/checkboxFormHelper.scala.html:1: Unused import
[warn] @(elements: helper.FieldElements)

[gmalouf]

Disabling -Xlint gets rid of the warnings - having said that this feels like a regression.

[mihaisoloi]

This is still happening with application code Binders imported into the routes file from build.sbt using routesImport and the -Ywarn-unused:imports flag in scalacOptions. I am not using the Binders on all of the controllers but I can't specify on which controller the import should be used, so I guess that's what leads to the issue.

scala 2.12.4
play 2.6.11

[steinybot]

This still occurs in Scala 2.12.5, play 2.6.12.

The warning comes from scala.tools.nsc.typechecker.Contexts#warnUnusedImports. The import it complains about is import _root_.controllers.Assets.Asset which is in ReverseRoutes.scala, JavaScriptReverseRoutes.scala and Routes.scala.

Adding:

routesImport := Seq.empty

To the bulid does solve the problem but it is annoying that this is needed.

[gavares]

This also seems to be triggered when using multiple routes files like:
conf/routes:

GET    /api/    controllers.MyController.showApiVersion
->     /ui      controllers.ui.MyUIController.serveUI

Compilation fails with:

/Users/gavares/workspace/my-proj/conf/routes: Unused import
/Users/gavares/workspace/my-proj/conf/routes: Unused import
two errors found

[iaco86]

I'm having the same problem while upgrading to play 2.6 and scala 2.12 - also the project is gradle-based so I was wondering if there's any workaround for gradle. I looked into it and couldn't find any...
Thanks!

[marcospereira]

Hi @iaco86, when using Gradle, I think you can tweak the defaultImports list to what you want/need.

[iaco86]

defaultImports seems to be using only the enum

public enum TwirlImports {
  SCALA, JAVA
}

[mihaisoloi]

I've introduced a way to silence the unused imports errors generated by the Play Routes in the scalac plugin silencer. You just need to add the following in your build.sbt

// silence all warnings on autogenerated files
scalacOptions += "-P:silencer:pathFilters=target/.*" 
// Make sure you only exclude warnings for the project directories, i.e. make builds reproducible
scalacOptions += s"-P:silencer:sourceRoots=${baseDirectory.value.getCanonicalPath}"

[iaco86]

I was following your PR, thanks a lot @mihaisoloi !

[balagez]

With Scala 2.13.2's configurable warnings you can suppress all warnings like this:

scalacOptions += s"-Wconf:src=${target.value}/.*:s"

[steinybot]

A variation on @mihaisoloi's solution which limits the scope of silencer a bit more:

    scalacOptions ++= Seq(
      s"-P:silencer:sourceRoots=${(Compile / routes / target).value}",
      s"-P:silencer:pathFilters=.*"
    ),

If you have other paths that you are filtering then you can relativize the target to the base directory and put that in the filter instead.

[leszekgruchala]

For anyone looking for a no-plugin solution, I've come up with a working one for Scala 2.13.7: https://stackoverflow.com/a/70418263/804812

[mkurz]

See https://github.com/slick/slick/blob/c4cb91a2ffe526411fc4cf117fd2512d032138fb/build.sbt#L45-L46