Why does SBT 0.12.2 resolve plugins with Scala 2.9.2 and ignore scalaVersion in build.sbt?

Question

SBT 0.12.2 always attempts to resolve plugins using Scala 2.9.2 when using the %% syntax on plugin imports.

I have tried setting older versions of Scala in build.sbt , newer versions, etc. Even deleting target folder each time... nothing seems to make a difference.

name := "Game"

version := "1.0"

scalaVersion := "2.9.1" // SBT is ignoring the scala version

Answer 1

SBT is recursive , so you need to specify scala version for project, that build your project. Another words, you need to add appropriate scalaVersion to the plugins.sbt file.

Answer 2

For all plugins in your project, you set scalaVersion in project/plugins.sbt file that configures the build project definition for your project and where you define plugins.

$ cat project/plugins.sbt
scalaVersion := "2.9.3"

There's however a way to set up a more specific version of sbt and Scala for a plugin.

Instead of using addSbtPlugin that accepts a single ModuleID (constructed with % and %% ), use addSbtPlugin(dependency: ModuleID, sbtVersion: String) or even addSbtPlugin(dependency: ModuleID, sbtVersion: String, scalaVersion: String) , eg

$ cat project/plugins.sbt
// It doesn't exist and it's only for demo purposes
addSbtPlugin("com.timushev.sbt" % "sbt-updates" % "0.1.0", "0.12.2", "2.5")