enable -deprecation for Scala 2.10

Enable -deprecation flag to catch old code being use when we migrate
things.
In this commit I moved error to sys.error.

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

@@ -92,7 +92,7 @@ trait Init[Scope] {
    * Only the static dependencies are tracked, however.  Dependencies on previous values do not introduce a derived setting either.
    */
   final def derive[T](s: Setting[T], allowDynamic: Boolean = false, filter: Scope => Boolean = const(true), trigger: AttributeKey[_] => Boolean = const(true), default: Boolean = false): Setting[T] = {
-    deriveAllowed(s, allowDynamic) foreach error
+    deriveAllowed(s, allowDynamic) foreach sys.error
     val d = new DerivedSetting[T](s.key, s.init, s.pos, filter, trigger)
     if (default) d.default() else d
   }
@@ -248,7 +248,7 @@ trait Init[Scope] {
     new Undefined(fakeUndefinedSetting(definingKey, derived), referencedKey)
   private[this] def fakeUndefinedSetting[T](definingKey: ScopedKey[T], d: Boolean): Setting[T] =
     {
-      val init: Initialize[T] = pure(() => error("Dummy setting for compatibility only."))
+      val init: Initialize[T] = pure(() => sys.error("Dummy setting for compatibility only."))
       new Setting(definingKey, init, NoPosition) { override def isDerived = d }
     }
 

util/complete/src/main/scala/sbt/complete/History.scala

@@ -13,7 +13,7 @@ final class History private (val lines: IndexedSeq[String], val path: Option[Fil
   def all: Seq[String] = lines
   def size = lines.length
   def !! : Option[String] = !-(1)
-  def apply(i: Int): Option[String] = if (0 <= i && i < size) Some(lines(i)) else { error("Invalid history index: " + i); None }
+  def apply(i: Int): Option[String] = if (0 <= i && i < size) Some(lines(i)) else { sys.error("Invalid history index: " + i); None }
   def !(i: Int): Option[String] = apply(i)
 
   def !(s: String): Option[String] =
@@ -27,7 +27,7 @@ final class History private (val lines: IndexedSeq[String], val path: Option[Fil
 
   private def nonEmpty[T](s: String)(act: => Option[T]): Option[T] =
     if (s.isEmpty) {
-      error("No action specified to history command")
+      sys.error("No action specified to history command")
       None
     } else
       act
@@ -37,7 +37,7 @@ final class History private (val lines: IndexedSeq[String], val path: Option[Fil
 }
 
 object History {
-  def apply(lines: Seq[String], path: Option[File], error: String => Unit): History = new History(lines.toIndexedSeq, path, error)
+  def apply(lines: Seq[String], path: Option[File], error: String => Unit): History = new History(lines.toIndexedSeq, path, sys.error)
 
   def number(s: String): Option[Int] =
     try { Some(s.toInt) }

util/logic/src/main/scala/sbt/logic/Logic.scala

@@ -225,7 +225,7 @@ object Logic {
         if (newlyFalse.nonEmpty)
           newlyFalse
         else // should never happen due to the acyclic negation rule
-          error(s"No progress:\n\tclauses: $clauses\n\tpossibly true: $possiblyTrue")
+          sys.error(s"No progress:\n\tclauses: $clauses\n\tpossibly true: $possiblyTrue")
       }
     }
 

util/logic/src/test/scala/sbt/logic/Test.scala

@@ -19,7 +19,7 @@ object LogicTest extends Properties("Logic") {
     Logic.reduceAll(badClauses, Set()) match {
       case Right(res)                      => false
       case Left(err: Logic.CyclicNegation) => true
-      case Left(err)                       => error(s"Expected cyclic error, got: $err")
+      case Left(err)                       => sys.error(s"Expected cyclic error, got: $err")
     }
   )
 
@@ -27,7 +27,7 @@ object LogicTest extends Properties("Logic") {
     case Left(err) => false
     case Right(res) =>
       val actual = res.provenSet
-      (actual == expected) || error(s"Expected to prove $expected, but actually proved $actual")
+      (actual == expected) || sys.error(s"Expected to prove $expected, but actually proved $actual")
   }
 }
 

util/process/src/main/scala/sbt/ProcessImpl.scala

@@ -131,7 +131,7 @@ private abstract class AbstractProcessBuilder extends ProcessBuilder with SinkPa
     {
       val buffer = new StringBuffer
       val code = this ! BasicIO(buffer, log, withIn)
-      if (code == 0) buffer.toString else error("Nonzero exit value: " + code)
+      if (code == 0) buffer.toString else sys.error("Nonzero exit value: " + code)
     }
   def !! = getString(None, false)
   def !!(log: ProcessLogger) = getString(Some(log), false)
@@ -190,7 +190,7 @@ private abstract class BasicProcess extends Process {
 
 private abstract class CompoundProcess extends BasicProcess {
   def destroy() { destroyer() }
-  def exitValue() = getExitValue().getOrElse(error("No exit code: process destroyed."))
+  def exitValue() = getExitValue().getOrElse(sys.error("No exit code: process destroyed."))
 
   def start() = getExitValue
 
@@ -426,7 +426,7 @@ private object Streamed {
       def next(): Stream[T] =
         q.take match {
           case Left(0)    => Stream.empty
-          case Left(code) => if (nonzeroException) error("Nonzero exit code: " + code) else Stream.empty
+          case Left(code) => if (nonzeroException) sys.error("Nonzero exit code: " + code) else Stream.empty
           case Right(s)   => Stream.cons(s, next)
         }
       new Streamed((s: T) => q.put(Right(s)), code => q.put(Left(code)), () => next())