Add -Ywarn-unused & -Ywarn-unused-import, & fix warnings

build.sbt

@@ -14,6 +14,7 @@ def commonSettings: Seq[Setting[_]] = Seq(
   testOptions += Tests.Argument(TestFrameworks.ScalaCheck, "-w", "1"),
   javacOptions in compile ++= Seq("-target", "6", "-source", "6", "-Xlint", "-Xlint:-serial"),
   crossScalaVersions := Seq(scala210, scala211),
+  scalacOptions ++= Seq("-Ywarn-unused", "-Ywarn-unused-import"),
   previousArtifact := None, // Some(organization.value %% moduleName.value % "1.0.0"),
   publishArtifact in Compile := true,
   publishArtifact in Test := false

internal/util-appmacro/src/main/scala/sbt/internal/util/appmacro/ContextUtil.scala

@@ -3,7 +3,6 @@ package appmacro
 
 import scala.reflect._
 import macros._
-import scala.tools.nsc.Global
 import ContextUtil.{ DynamicDependencyError, DynamicReferenceError }
 
 object ContextUtil {

internal/util-appmacro/src/main/scala/sbt/internal/util/appmacro/Instance.scala

@@ -23,7 +23,6 @@ trait MonadInstance extends Instance {
 
 import scala.reflect._
 import macros._
-import reflect.internal.annotations.compileTimeOnly
 
 object Instance {
   final val ApplyName = "app"

internal/util-appmacro/src/main/scala/sbt/internal/util/appmacro/KListBuilder.scala

@@ -1,8 +1,6 @@
 package sbt.internal.util
 package appmacro
 
-import Types.Id
-import scala.tools.nsc.Global
 import scala.reflect._
 import macros._
 
@@ -59,7 +57,6 @@ object KListBuilder extends TupleBuilder {
     val klistType: Type = (inputs :\ knilType)((in, klist) => kconsType(in.tpe, klist))
 
     val representationC = internal.polyType(tcVariable :: Nil, klistType)
-    val resultType = appliedType(representationC, idTC :: Nil)
     val input = klist
     val alistInstance: ctx.universe.Tree = TypeApply(select(Ident(alist), "klist"), TypeTree(representationC) :: Nil)
     def extract(param: ValDef) = bindKList(param, Nil, inputs.map(_.local))

internal/util-appmacro/src/main/scala/sbt/internal/util/appmacro/TupleBuilder.scala

@@ -1,8 +1,6 @@
 package sbt.internal.util
 package appmacro
 
-import Types.Id
-import scala.tools.nsc.Global
 import scala.reflect._
 import macros._
 

internal/util-appmacro/src/main/scala/sbt/internal/util/appmacro/TupleNBuilder.scala

@@ -1,7 +1,6 @@
 package sbt.internal.util
 package appmacro
 
-import Types.Id
 import scala.tools.nsc.Global
 import scala.reflect._
 import macros._
@@ -17,11 +16,10 @@ object TupleNBuilder extends TupleBuilder {
 
   def make(c: blackbox.Context)(mt: c.Type, inputs: Inputs[c.universe.type]): BuilderResult[c.type] = new BuilderResult[c.type] {
     val util = ContextUtil[c.type](c)
-    import c.universe.{ Apply => ApplyTree, _ }
+    import c.universe._
     import util._
 
     val global: Global = c.universe.asInstanceOf[Global]
-    val mTC: Type = mt.asInstanceOf[c.universe.Type]
 
     val ctx: c.type = c
     val representationC: PolyType = {
@@ -30,7 +28,6 @@ object TupleNBuilder extends TupleBuilder {
       val tuple = global.definitions.tupleType(tupleTypeArgs)
       internal.polyType(tcVariable :: Nil, tuple.asInstanceOf[Type])
     }
-    val resultType = appliedType(representationC, idTC :: Nil)
 
     val input: Tree = mkTuple(inputs.map(_.expr))
     val alistInstance: Tree = {

internal/util-cache/src/main/scala/sbt/internal/util/Cache.scala

@@ -7,7 +7,7 @@ import sbinary.{ CollectionTypes, DefaultProtocol, Format, Input, JavaFormats, O
 import java.io.{ ByteArrayInputStream, ByteArrayOutputStream, File, InputStream, OutputStream }
 import java.net.{ URI, URL }
 import Types.:+:
-import DefaultProtocol.{ asProduct2, asSingleton, BooleanFormat, ByteFormat, IntFormat, wrap }
+import DefaultProtocol.{ asSingleton, BooleanFormat, ByteFormat, IntFormat, wrap }
 import scala.xml.NodeSeq
 import scala.language.existentials
 

internal/util-cache/src/main/scala/sbt/internal/util/CacheIO.scala

@@ -3,7 +3,7 @@
  */
 package sbt.internal.util
 
-import java.io.{ File, FileNotFoundException }
+import java.io.File
 import sbinary.{ DefaultProtocol, Format, Operations }
 import scala.reflect.Manifest
 import sbt.io.IO

internal/util-cache/src/main/scala/sbt/internal/util/FileInfo.scala

@@ -3,7 +3,7 @@
  */
 package sbt.internal.util
 
-import java.io.{ File, IOException }
+import java.io.File
 import sbinary.{ DefaultProtocol, Format }
 import DefaultProtocol._
 import scala.reflect.Manifest

internal/util-cache/src/main/scala/sbt/internal/util/SeparatedCache.scala

@@ -3,10 +3,8 @@
  */
 package sbt.internal.util
 
-import Types.:+:
+import sbinary.{ Format, Input, Output => Out }
-import sbinary.{ DefaultProtocol, Format, Input, Output => Out }
+import java.io.File
-import DefaultProtocol.ByteFormat
-import java.io.{ File, InputStream, OutputStream }
 import sbt.io.Using
 
 trait InputCache[I] {

internal/util-collection/src/main/scala/sbt/internal/util/Dag.scala

@@ -94,7 +94,6 @@ object Dag {
    */
   private[sbt] def findNegativeCycle[Node](graph: DirectedSignedGraph[Node]): List[graph.Arrow] =
     {
-      import scala.annotation.tailrec
       import graph._
       val finished = new mutable.HashSet[Node]
       val visited = new mutable.HashSet[Node]

internal/util-collection/src/main/scala/sbt/internal/util/INode.scala

@@ -3,7 +3,7 @@ package sbt.internal.util
 import java.lang.Runnable
 import java.util.concurrent.{ atomic, Executor, LinkedBlockingQueue }
 import atomic.{ AtomicBoolean, AtomicInteger }
-import Types.{ :+:, ConstK, Id }
+import Types.{ ConstK, Id }
 
 object EvaluationState extends Enumeration {
   val New, Blocked, Ready, Calling, Evaluated = Value

internal/util-collection/src/main/scala/sbt/internal/util/Param.scala

@@ -3,8 +3,6 @@
  */
 package sbt.internal.util
 
-import Types._
-
 // Used to emulate ~> literals
 trait Param[A[_], B[_]] {
   type T

internal/util-collection/src/main/scala/sbt/internal/util/Settings.scala

@@ -278,7 +278,6 @@ trait Init[Scope] {
 
   def flattenLocals(compiled: CompiledMap): Map[ScopedKey[_], Flattened] =
     {
-      import collection.breakOut
       val locals = compiled flatMap { case (key, comp) => if (key.key.isLocal) Seq[Compiled[_]](comp) else Nil }
       val ordered = Dag.topologicalSort(locals)(_.dependencies.flatMap(dep => if (dep.key.isLocal) Seq[Compiled[_]](compiled(dep)) else Nil))
       def flatten(cmap: Map[ScopedKey[_], Flattened], key: ScopedKey[_], deps: Iterable[ScopedKey[_]]): Flattened =
@@ -340,11 +339,6 @@ trait Init[Scope] {
         derivsByDef.getOrElseUpdate(key, new Deriveds(key, new mutable.ListBuffer)).settings += s
       }
 
-      // sort derived settings so that dependencies come first
-      // this is necessary when verifying that a derived setting's dependencies exist
-      val ddeps = (d: Deriveds) => d.dependencies.flatMap(derivsByDef.get)
-      val sortedDerivs = Dag.topologicalSort(derivsByDef.values)(ddeps)
-
       // index derived settings by triggering key.  This maps a key to the list of settings potentially derived from it.
       val derivedBy = new mutable.HashMap[AttributeKey[_], mutable.ListBuffer[Derived]]
       for (s <- derived; d <- s.triggeredBy)

internal/util-collection/src/test/scala/LiteralTest.scala

@@ -3,8 +3,6 @@
  */
 package sbt.internal.util
 
-import Types._
-
 // compilation test
 object LiteralTest {
   def x[A[_], B[_]](f: A ~> B) = f

internal/util-collection/src/test/scala/SettingsExample.scala

@@ -32,7 +32,6 @@ object SettingsExample extends Init[Scope] {
 
 object SettingsUsage {
   import SettingsExample._
-  import Types._
 
   // Define some keys
   val a = AttributeKey[Int]("a")

internal/util-complete/src/main/scala/sbt/internal/util/LineReader.scala

@@ -5,9 +5,8 @@ package sbt.internal.util
 
 import jline.console.ConsoleReader
 import jline.console.history.{ FileHistory, MemoryHistory }
-import java.io.{ File, InputStream, PrintWriter, FileInputStream, FileDescriptor, FilterInputStream }
+import java.io.{ File, InputStream, FileInputStream, FileDescriptor, FilterInputStream }
 import complete.Parser
-import java.util.concurrent.atomic.AtomicBoolean
 import scala.concurrent.duration.Duration
 import scala.annotation.tailrec
 

internal/util-complete/src/main/scala/sbt/internal/util/complete/EditDistance.scala

@@ -23,7 +23,6 @@ object EditDistance {
     for (i <- 1 to n; s_i = s(i - 1); j <- 1 to m) {
       val t_j = t(j - 1)
       val cost = if (s_i == t_j) matchCost else if (lower(s_i) == lower(t_j)) caseCost else subCost
-      val tcost = if (s_i == t_j) matchCost else transposeCost
 
       val c1 = d(i - 1)(j) + deleteCost
       val c2 = d(i)(j - 1) + insertCost

internal/util-complete/src/main/scala/sbt/internal/util/complete/HistoryCommands.scala

@@ -4,7 +4,6 @@
 package sbt.internal.util
 package complete
 
-import java.io.File
 import sbt.io.IO
 
 object HistoryCommands {

internal/util-complete/src/main/scala/sbt/internal/util/complete/JLineCompletion.scala

@@ -5,7 +5,7 @@ package sbt.internal.util
 package complete
 
 import jline.console.ConsoleReader
-import jline.console.completer.{ CandidateListCompletionHandler, Completer, CompletionHandler }
+import jline.console.completer.{ Completer, CompletionHandler }
 import scala.annotation.tailrec
 import collection.JavaConversions
 

internal/util-logging/src/main/scala/sbt/internal/util/ConsoleOut.scala

@@ -1,6 +1,5 @@
 package sbt.internal.util
 
-import sbt.util._
 import java.io.{ BufferedWriter, PrintStream, PrintWriter }
 
 sealed trait ConsoleOut {

internal/util-logging/src/test/scala/LogWriterTest.scala

@@ -5,7 +5,7 @@ package sbt.internal.util
 
 import sbt.util._
 import org.scalacheck._
-import Arbitrary.{ arbitrary => arb, _ }
+import Arbitrary._
 import Gen.{ listOfN, oneOf }
 import Prop._
 

internal/util-scripted/src/main/scala/sbt/internal/scripted/ScriptedTests.scala

@@ -6,7 +6,7 @@ import java.io.File
 import sbt.util.Logger
 import sbt.internal.util.{ ConsoleLogger, BufferedLogger, FullLogger }
 import sbt.io.IO.wrapNull
-import sbt.io.{ DirectoryFilter, HiddenFileFilter, Path, GlobFilter }
+import sbt.io.{ DirectoryFilter, HiddenFileFilter }
 import sbt.io.syntax._
 import sbt.internal.io.Resources
 
@@ -49,9 +49,6 @@ final class ScriptedTests(resourceBaseDirectory: File, bufferLog: Boolean, handl
   def scriptedTest(group: String, name: String, log: Logger): Seq[() => Option[String]] =
     scriptedTest(group, name, { _ => () }, log)
   def scriptedTest(group: String, name: String, prescripted: File => Unit, log: Logger): Seq[() => Option[String]] = {
-    import Path._
-    import GlobFilter._
-    var failed = false
     for (groupDir <- (resourceBaseDirectory * group).get; nme <- (groupDir * name).get) yield {
       val g = groupDir.getName
       val n = nme.getName

internal/util-scripted/src/main/scala/sbt/internal/scripted/TestScriptParser.scala

@@ -5,7 +5,7 @@ package sbt
 package internal
 package scripted
 
-import java.io.{ BufferedReader, File, InputStreamReader }
+import java.io.File
 import scala.util.parsing.combinator._
 import scala.util.parsing.input.Positional
 import Character.isWhitespace

internal/util-tracking/src/main/scala/sbt/internal/util/Tracked.scala

@@ -8,9 +8,8 @@ import CacheIO.{ fromFile, toFile }
 import sbinary.Format
 import scala.pickling.PicklingException
 import scala.reflect.Manifest
-import scala.collection.mutable
 import sbt.io.IO.{ delete, read, write }
-import sbt.io.{ IO, Path }
+import sbt.io.IO
 import sbt.io.Using
 import sbt.io.syntax._
 import sbt.serialization._
@@ -257,7 +256,6 @@ object FileFunction {
 
   def cached(cacheBaseDirectory: File)(inStyle: FilesInfo.Style, outStyle: FilesInfo.Style)(action: UpdateFunction): Set[File] => Set[File] =
     {
-      import Path._
       lazy val inCache = Difference.inputs(cacheBaseDirectory / "in-cache", inStyle)
       lazy val outCache = Difference.outputs(cacheBaseDirectory / "out-cache", outStyle)
       inputs =>