Remove snapshotScalaBinaryVersion

It only has an effect if the Scala version number is exactly
2.11.0-SNAPSHOT. For 2.11.x-SNAPSHOT with x > 0, sbt already sets
the scalaBinaryVersion to 2.11.

Note that our nightly release builds don't use -SNAPSHOT for the
Scala version, but something like 2.12.0-[sha]-nightly.

Author: lrytz

src/main/scala/ScalaModulePlugin.scala

@@ -4,33 +4,19 @@ import com.typesafe.sbt.osgi.{OsgiKeys, SbtOsgi}
 import com.typesafe.tools.mima.plugin.{MimaPlugin, MimaKeys}
 
 object ScalaModulePlugin extends Plugin {
-  // TODO add doc. not sure i really see the valid use case for this feature. yet.
-  //  - only relevant for x.y.0-SNAPSHOT, once x.y.0 is out, the binary ver of x.y.1-SNAPSHOT is x.y (patch is dropped)
-  //  - used when publishing using a scala snapshot. the module will not have SNAPSHOT in the scala binary version.
-  //    allows using a snapshot of the module more easily. eg if you're using scala 2.12.0-M1, you can say "org.scala-lang.modules" %% "scala-xml" % "1.0.2-SNAPSHOT"
-  //  - also used to resolve dependencies of modules. when building with a snapshot scala, deps will be resolved against this binver.
-  val snapshotScalaBinaryVersion = settingKey[String]("The Scala binary version to use when building against Scala SNAPSHOT.")
   val repoName                   = settingKey[String]("The name of the repository under github.com/scala/.")
   val mimaPreviousVersion        = settingKey[Option[String]]("The version of this module to compare against when running MiMa.")
 
   private val canRunMima         = taskKey[Boolean]("Decides if MiMa should run.")
   private val runMimaIfEnabled   = taskKey[Unit]("Run MiMa if mimaPreviousVersion and the module can be resolved against the current scalaBinaryVersion.")
 
-  def deriveBinaryVersion(sv: String, snapshotScalaBinaryVersion: String) = sv match {
-    case snap_211 if snap_211.startsWith("2.11") &&
-                     snap_211.contains("-SNAPSHOT") => snapshotScalaBinaryVersion
-    case sv => sbt.CrossVersion.binaryScalaVersion(sv)
-  }
-
   lazy val scalaModuleSettings: Seq[Setting[_]] = Seq(
     repoName            := name.value,
 
     mimaPreviousVersion := None,
 
     organization        := "org.scala-lang.modules",
 
-    scalaBinaryVersion  := deriveBinaryVersion(scalaVersion.value, snapshotScalaBinaryVersion.value),
-
     // so we don't have to wait for sonatype to synch to maven central when deploying a new module
     resolvers += Resolver.sonatypeRepo("releases"),