scalafix

sbt-scalafix

The sbt-plugin is the recommended integration for semantic rules.

// ===> project/plugins.sbt
addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.5.2")

// ===> build.sbt
scalaVersion := "2.12.3" // 2.11.11 is also supported.
// if scalacOptions is defined with append `++=`, do nothing.
// if scalacOptions is defined like this: scalacOptions := List(...),
// then do one of the following
scalacOptions ++= List(...) // change := to ++=
// or
scalacOptions := List(...)                    // keep unchanged
scalacOptions ++= scalafixScalacOptions.value // add this line

// ===> sbt shell (example usage)
> scalafix                               // Run .scalafix.conf rules
> scalafix RemoveUnusedImports           // Run specific rule
> myProject/scalafix RemoveUnusedImports // Run rule in one project only
> test:scalafix RemoveUnusedImports      // Run rule in single configuration
> scalafix ExplicitR<TAB>                // use tab completion
> scalafix replace:com.foobar/com.buzbaz // refactor (experimental)
> scalafix file:rules/MyRule.scala       // run local custom rule
> scalafix github:org/repo/v1            // run library migration rule

Verify sbt installation

To verify the installation, check that the scalacOptions include -Xplugin-require:semanticdb

> show scalacOptions
[info] * -Yrangepos                  // required
[info] * -Xplugin-require:semanticdb // recommended
[info] * -P:semanticdb:sourceroot:/x  // recommended
> show libraryDependencies
[info] * org.scalameta:semanticdb-scalac:2.0.1:plugin->default(compile)

scalafix-sbt-example

For a minimal working example usage of sbt-scalafix, see the scalacenter/scalafix-sbt-example repository.

git clone https://github.com/olafurpg/scalafix-sbt-example
cd scalafix-sbt-example
sbt "scalafix RemoveUnusedImports"
git diff // should produce a diff

sbt settings and tasks

Name	Type	Description
`scalafix <rule>..`	`Unit`	Run scalafix on project sources. See Rules or use tab completion to explore supported rules.
`sbtfix <rule>..`	`Unit`	Run scalafix on the build sources, `.sbt` and `project/`. Note: Requires semanticdb-sbt enabled globally for semantic rules.
`scalafixEnabled`	`Boolean`	`true` by default. If `false`, then sbt-scalafix will not enable the semanticdb-scalac plugin.
`scalafixSourceRoot`	`File`	The root directory of this project.
`scalafixScalacOptions`	`Seq[String]`	Necessary Scala compiler settings for scalafix to work.
`scalafixVersion`	`String`	Which version of scalafix-cli to run.
`scalafixScalaVersion`	`String`	Which Scala version of scalafix-cli to run.
`scalafixSemanticdbVersion`	`String`	Which version of org.scalameta:semanticdb-scalac to run.
`scalafixVerbose`	`Boolean`	If `true`, print out debug information.

semanticdb-sbt

⚠️ Experimental

semanticdb-sbt is a Scala 2.10 compiler plugin that extracts semantic information from the sbt compiler. To enable semanticdb-sbt,

// ~/.sbt/0.13/plugins/plugins.sbt
addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "@V.stableVersion")
// ~/.sbt/0.13/build.sbt
import scalafix.sbt.ScalafixPlugin.autoImport._
sbtfixSettings // enable semanticdb-sbt for sbt metabuilds.

Note. This integration is new, you can expect to face problems from enabling sbt-scalafix globally. In particular, sbt-scalafix does not at the moment support older versions of 2.11 than 2.11.11 and 2.12 than 2.12.3. It’s possible to disable sbt-scalafix with scalafixEnabled := false. Please report back on your experience.