diff --git a/main-settings/src/main/scala/sbt/std/InputConvert.scala b/main-settings/src/main/scala/sbt/std/InputConvert.scala
index 3c993899b..0a7b99ab5 100644
--- a/main-settings/src/main/scala/sbt/std/InputConvert.scala
+++ b/main-settings/src/main/scala/sbt/std/InputConvert.scala
@@ -8,7 +8,7 @@ import sbt.internal.util.complete.Parser
 import sbt.internal.util.appmacro.{ Convert, Converted }
 
 object InputInitConvert extends Convert {
-  def apply[T: c.WeakTypeTag](c: Context)(nme: String, in: c.Tree): Converted[c.type] =
+  def apply[T: c.WeakTypeTag](c: blackbox.Context)(nme: String, in: c.Tree): Converted[c.type] =
     nme match {
       case InputWrapper.WrapInitName     => Converted.Success(in)
       case InputWrapper.WrapInitTaskName => Converted.Failure(in.pos, initTaskErrorMessage)
@@ -20,7 +20,7 @@ object InputInitConvert extends Convert {
 
 /** Converts an input `Tree` of type `Parser[T]` or `State => Parser[T]` into a `Tree` of type `State => Parser[T]`.*/
 object ParserConvert extends Convert {
-  def apply[T: c.WeakTypeTag](c: Context)(nme: String, in: c.Tree): Converted[c.type] =
+  def apply[T: c.WeakTypeTag](c: blackbox.Context)(nme: String, in: c.Tree): Converted[c.type] =
     nme match {
       case ParserInput.WrapName     => Converted.Success(in)
       case ParserInput.WrapInitName => Converted.Failure(in.pos, initParserErrorMessage)
@@ -32,14 +32,14 @@ object ParserConvert extends Convert {
 
 /** Convert instance for plain `Task`s not within the settings system. */
 object TaskConvert extends Convert {
-  def apply[T: c.WeakTypeTag](c: Context)(nme: String, in: c.Tree): Converted[c.type] =
+  def apply[T: c.WeakTypeTag](c: blackbox.Context)(nme: String, in: c.Tree): Converted[c.type] =
     if (nme == InputWrapper.WrapTaskName) Converted.Success(in) else Converted.NotApplicable
 }
 
 /** Converts an input `Tree` of type `Initialize[T]`, `Initialize[Task[T]]`, or `Task[T]` into a `Tree` of type `Initialize[Task[T]]`.*/
 object FullConvert extends Convert {
   import InputWrapper._
-  def apply[T: c.WeakTypeTag](c: Context)(nme: String, in: c.Tree): Converted[c.type] =
+  def apply[T: c.WeakTypeTag](c: blackbox.Context)(nme: String, in: c.Tree): Converted[c.type] =
     nme match {
       case WrapInitTaskName => Converted.Success(in)
       case WrapPreviousName => Converted.Success(in)
@@ -48,13 +48,13 @@ object FullConvert extends Convert {
       case _                => Converted.NotApplicable
     }
 
-  private def wrapInit[T](c: Context)(tree: c.Tree): Converted[c.type] = {
+  private def wrapInit[T](c: blackbox.Context)(tree: c.Tree): Converted[c.type] = {
     val i = c.Expr[Initialize[T]](tree)
     val t = c.universe.reify(Def.toITask(i.splice)).tree
     Converted.Success(t)
   }
 
-  private def wrapTask[T](c: Context)(tree: c.Tree): Converted[c.type] = {
+  private def wrapTask[T](c: blackbox.Context)(tree: c.Tree): Converted[c.type] = {
     val i = c.Expr[Task[T]](tree)
     val t = c.universe.reify(Def.valueStrict[Task[T]](i.splice)).tree
     Converted.Success(t)
@@ -66,14 +66,14 @@ object FullConvert extends Convert {
  * into a `Tree` of type `Initialize[State => Parser[T]]`.
  */
 object InitParserConvert extends Convert {
-  def apply[T: c.WeakTypeTag](c: Context)(nme: String, in: c.Tree): Converted[c.type] =
+  def apply[T: c.WeakTypeTag](c: blackbox.Context)(nme: String, in: c.Tree): Converted[c.type] =
     nme match {
       case ParserInput.WrapName     => wrap[T](c)(in)
       case ParserInput.WrapInitName => Converted.Success(in)
       case _                        => Converted.NotApplicable
     }
 
-  private def wrap[T](c: Context)(tree: c.Tree): Converted[c.type] = {
+  private def wrap[T](c: blackbox.Context)(tree: c.Tree): Converted[c.type] = {
     val e = c.Expr[State => Parser[T]](tree)
     val t = c.universe.reify { Def.valueStrict[State => Parser[T]](e.splice) }
     Converted.Success(t.tree)
diff --git a/main-settings/src/main/scala/sbt/std/InputWrapper.scala b/main-settings/src/main/scala/sbt/std/InputWrapper.scala
index 2e54ecbc6..93dd79f87 100644
--- a/main-settings/src/main/scala/sbt/std/InputWrapper.scala
+++ b/main-settings/src/main/scala/sbt/std/InputWrapper.scala
@@ -42,19 +42,19 @@ object InputWrapper {
 
   private[this] def implDetailError = sys.error("This method is an implementation detail and should not be referenced.")
 
-  private[std] def wrapTask[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
+  private[std] def wrapTask[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
     wrapImpl[T, InputWrapper.type](c, InputWrapper, WrapTaskName)(ts, pos)
-  private[std] def wrapInit[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
+  private[std] def wrapInit[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
     wrapImpl[T, InputWrapper.type](c, InputWrapper, WrapInitName)(ts, pos)
-  private[std] def wrapInitTask[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
+  private[std] def wrapInitTask[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
     wrapImpl[T, InputWrapper.type](c, InputWrapper, WrapInitTaskName)(ts, pos)
 
-  private[std] def wrapInitInputTask[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
+  private[std] def wrapInitInputTask[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
     wrapImpl[T, InputWrapper.type](c, InputWrapper, WrapInitInputName)(ts, pos)
-  private[std] def wrapInputTask[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
+  private[std] def wrapInputTask[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
     wrapImpl[T, InputWrapper.type](c, InputWrapper, WrapInputName)(ts, pos)
 
-  private[std] def wrapPrevious[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[Option[T]] =
+  private[std] def wrapPrevious[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[Option[T]] =
     wrapImpl[Option[T], InputWrapper.type](c, InputWrapper, WrapPreviousName)(ts, pos)
 
   /**
@@ -63,7 +63,7 @@ object InputWrapper {
    *
    * `c.universe.reify { <s>.<wrapName>[T](ts.splice) }`
    */
-  def wrapImpl[T: c.WeakTypeTag, S <: AnyRef with Singleton](c: Context, s: S, wrapName: String)(ts: c.Expr[Any], pos: c.Position)(implicit it: c.TypeTag[s.type]): c.Expr[T] =
+  def wrapImpl[T: c.WeakTypeTag, S <: AnyRef with Singleton](c: blackbox.Context, s: S, wrapName: String)(ts: c.Expr[Any], pos: c.Position)(implicit it: c.TypeTag[s.type]): c.Expr[T] =
     {
       import c.universe.{ Apply => ApplyTree, _ }
       import internal.decorators._
@@ -87,7 +87,7 @@ object InputWrapper {
       c.Expr[T](typedTree)
     }
 
-  def valueMacroImpl[T: c.WeakTypeTag](c: Context): c.Expr[T] =
+  def valueMacroImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[T] =
     ContextUtil.selectMacroImpl[T](c) { (ts, pos) =>
       ts.tree.tpe match {
         case tpe if tpe <:< c.weakTypeOf[Initialize[T]] =>
@@ -103,11 +103,11 @@ object InputWrapper {
         case tpe                                                   => unexpectedType(c)(pos, tpe)
       }
     }
-  def inputTaskValueMacroImpl[T: c.WeakTypeTag](c: Context): c.Expr[InputTask[T]] =
+  def inputTaskValueMacroImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[InputTask[T]] =
     ContextUtil.selectMacroImpl[InputTask[T]](c) { (ts, pos) =>
       InputWrapper.wrapInit[InputTask[T]](c)(ts, pos)
     }
-  def taskValueMacroImpl[T: c.WeakTypeTag](c: Context): c.Expr[Task[T]] =
+  def taskValueMacroImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[Task[T]] =
     ContextUtil.selectMacroImpl[Task[T]](c) { (ts, pos) =>
       val tpe = ts.tree.tpe
       if (tpe <:< c.weakTypeOf[Initialize[Task[T]]])
@@ -116,7 +116,7 @@ object InputWrapper {
         unexpectedType(c)(pos, tpe)
     }
   /** Translates <task: TaskKey[T]>.previous(format) to Previous.runtime(<task>)(format).value*/
-  def previousMacroImpl[T: c.WeakTypeTag](c: Context)(format: c.Expr[sbinary.Format[T]]): c.Expr[Option[T]] =
+  def previousMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(format: c.Expr[sbinary.Format[T]]): c.Expr[Option[T]] =
     {
       import c.universe._
       c.macroApplication match {
@@ -131,7 +131,7 @@ object InputWrapper {
       }
     }
 
-  private def unexpectedType(c: Context)(pos: c.Position, tpe: c.Type) =
+  private def unexpectedType(c: blackbox.Context)(pos: c.Position, tpe: c.Type) =
     c.abort(pos, s"Internal sbt error. Unexpected type ${tpe.widen}")
 }
 
@@ -176,14 +176,14 @@ object ParserInput {
   @compileTimeOnly("`parsed` can only be used within an input task macro, such as := or Def.inputTask.")
   def initParser_\u2603\u2603[T](i: Any): T = sys.error("This method is an implementation detail and should not be referenced.")
 
-  private[std] def wrap[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
+  private[std] def wrap[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
     InputWrapper.wrapImpl[T, ParserInput.type](c, ParserInput, WrapName)(ts, pos)
-  private[std] def wrapInit[T: c.WeakTypeTag](c: Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
+  private[std] def wrapInit[T: c.WeakTypeTag](c: blackbox.Context)(ts: c.Expr[Any], pos: c.Position): c.Expr[T] =
     InputWrapper.wrapImpl[T, ParserInput.type](c, ParserInput, WrapInitName)(ts, pos)
 
-  private[std] def inputParser[T: c.WeakTypeTag](c: Context)(t: c.Expr[InputTask[T]]): c.Expr[State => Parser[Task[T]]] = c.universe.reify(t.splice.parser)
+  private[std] def inputParser[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[InputTask[T]]): c.Expr[State => Parser[Task[T]]] = c.universe.reify(t.splice.parser)
 
-  def parsedInputMacroImpl[T: c.WeakTypeTag](c: Context): c.Expr[Task[T]] =
+  def parsedInputMacroImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[Task[T]] =
     ContextUtil.selectMacroImpl[Task[T]](c) { (p, pos) =>
       p.tree.tpe match {
         case tpe if tpe <:< c.weakTypeOf[InputTask[T]]             => wrapInputTask[T](c)(p.tree, pos)
@@ -192,18 +192,18 @@ object ParserInput {
       }
     }
 
-  private def wrapInputTask[T: c.WeakTypeTag](c: Context)(tree: c.Tree, pos: c.Position) = {
+  private def wrapInputTask[T: c.WeakTypeTag](c: blackbox.Context)(tree: c.Tree, pos: c.Position) = {
     val e = c.Expr[InputTask[T]](tree)
     wrap[Task[T]](c)(inputParser(c)(e), pos)
   }
 
-  private def wrapInitInputTask[T: c.WeakTypeTag](c: Context)(tree: c.Tree, pos: c.Position) = {
+  private def wrapInitInputTask[T: c.WeakTypeTag](c: blackbox.Context)(tree: c.Tree, pos: c.Position) = {
     val e = c.Expr[Initialize[InputTask[T]]](tree)
     wrapInit[Task[T]](c)(c.universe.reify {Def.toIParser(e.splice)}, pos)
   }
 
   /** Implements `Parser[T].parsed` by wrapping the Parser with the ParserInput wrapper.*/
-  def parsedMacroImpl[T: c.WeakTypeTag](c: Context): c.Expr[T] =
+  def parsedMacroImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Expr[T] =
     ContextUtil.selectMacroImpl[T](c) { (p, pos) =>
       p.tree.tpe match {
         case tpe if tpe <:< c.weakTypeOf[Parser[T]]                      => wrapParser[T](c)(p.tree, pos)
@@ -214,17 +214,17 @@ object ParserInput {
       }
     }
 
-  private def wrapParser[T: c.WeakTypeTag](c: Context)(tree: c.Tree, pos: c.Position) = {
+  private def wrapParser[T: c.WeakTypeTag](c: blackbox.Context)(tree: c.Tree, pos: c.Position) = {
     val e = c.Expr[Parser[T]](tree)
     wrap[T](c)(c.universe.reify {Def.toSParser(e.splice)}, pos)
   }
 
-  private def wrapInitParser[T: c.WeakTypeTag](c: Context)(tree: c.Tree, pos: c.Position) = {
+  private def wrapInitParser[T: c.WeakTypeTag](c: blackbox.Context)(tree: c.Tree, pos: c.Position) = {
     val e = c.Expr[Initialize[Parser[T]]](tree)
     val es = c.universe.reify {Def.toISParser(e.splice)}
     wrapInit[T](c)(es, pos)
   }
 
-  private def unexpectedType(c: Context)(pos: c.Position, tpe: c.Type, label: String) =
+  private def unexpectedType(c: blackbox.Context)(pos: c.Position, tpe: c.Type, label: String) =
     c.abort(pos, s"Internal sbt error. Unexpected type ${tpe.dealias} in $label.")
 }
diff --git a/main-settings/src/main/scala/sbt/std/KeyMacro.scala b/main-settings/src/main/scala/sbt/std/KeyMacro.scala
index 972d78388..1218691b5 100644
--- a/main-settings/src/main/scala/sbt/std/KeyMacro.scala
+++ b/main-settings/src/main/scala/sbt/std/KeyMacro.scala
@@ -4,20 +4,20 @@ package std
 import reflect.macros._
 
 private[sbt] object KeyMacro {
-  def settingKeyImpl[T: c.WeakTypeTag](c: Context)(description: c.Expr[String]): c.Expr[SettingKey[T]] =
+  def settingKeyImpl[T: c.WeakTypeTag](c: blackbox.Context)(description: c.Expr[String]): c.Expr[SettingKey[T]] =
     keyImpl[T, SettingKey[T]](c) { (name, mf) =>
       c.universe.reify { SettingKey[T](name.splice, description.splice)(mf.splice) }
     }
-  def taskKeyImpl[T: c.WeakTypeTag](c: Context)(description: c.Expr[String]): c.Expr[TaskKey[T]] =
+  def taskKeyImpl[T: c.WeakTypeTag](c: blackbox.Context)(description: c.Expr[String]): c.Expr[TaskKey[T]] =
     keyImpl[T, TaskKey[T]](c) { (name, mf) =>
       c.universe.reify { TaskKey[T](name.splice, description.splice)(mf.splice) }
     }
-  def inputKeyImpl[T: c.WeakTypeTag](c: Context)(description: c.Expr[String]): c.Expr[InputKey[T]] =
+  def inputKeyImpl[T: c.WeakTypeTag](c: blackbox.Context)(description: c.Expr[String]): c.Expr[InputKey[T]] =
     keyImpl[T, InputKey[T]](c) { (name, mf) =>
       c.universe.reify { InputKey[T](name.splice, description.splice)(mf.splice) }
     }
 
-  def keyImpl[T: c.WeakTypeTag, S: c.WeakTypeTag](c: Context)(f: (c.Expr[String], c.Expr[Manifest[T]]) => c.Expr[S]): c.Expr[S] =
+  def keyImpl[T: c.WeakTypeTag, S: c.WeakTypeTag](c: blackbox.Context)(f: (c.Expr[String], c.Expr[Manifest[T]]) => c.Expr[S]): c.Expr[S] =
     {
       import c.universe._
       val enclosingValName = definingValName(c, methodName => s"""$methodName must be directly assigned to a val, such as `val x = $methodName[Int]("description")`.""")
@@ -25,7 +25,7 @@ private[sbt] object KeyMacro {
       val mf = c.Expr[Manifest[T]](c.inferImplicitValue(weakTypeOf[Manifest[T]]))
       f(name, mf)
     }
-  def definingValName(c: Context, invalidEnclosingTree: String => String): String =
+  def definingValName(c: blackbox.Context, invalidEnclosingTree: String => String): String =
     {
       import c.universe.{ Apply => ApplyTree, _ }
       val methodName = c.macroApplication.symbol.name
@@ -44,6 +44,6 @@ private[sbt] object KeyMacro {
         }
       enclosingVal(enclosingTrees(c).toList)
     }
-  def enclosingTrees(c: Context): Seq[c.Tree] =
+  def enclosingTrees(c: blackbox.Context): Seq[c.Tree] =
     c.asInstanceOf[reflect.macros.runtime.Context].callsiteTyper.context.enclosingContextChain.map(_.tree.asInstanceOf[c.Tree])
 }
diff --git a/main-settings/src/main/scala/sbt/std/SettingMacro.scala b/main-settings/src/main/scala/sbt/std/SettingMacro.scala
index 4c7ab7379..1fc0dda4a 100644
--- a/main-settings/src/main/scala/sbt/std/SettingMacro.scala
+++ b/main-settings/src/main/scala/sbt/std/SettingMacro.scala
@@ -17,7 +17,7 @@ object InitializeInstance extends MonadInstance {
 import reflect.macros._
 
 object InitializeConvert extends Convert {
-  def apply[T: c.WeakTypeTag](c: Context)(nme: String, in: c.Tree): Converted[c.type] =
+  def apply[T: c.WeakTypeTag](c: blackbox.Context)(nme: String, in: c.Tree): Converted[c.type] =
     nme match {
       case InputWrapper.WrapInitName                                 => convert[T](c)(in)
       case InputWrapper.WrapTaskName | InputWrapper.WrapInitTaskName => failTask[c.type](c)(in.pos)
@@ -25,23 +25,23 @@ object InitializeConvert extends Convert {
       case _                                                         => Converted.NotApplicable
     }
 
-  private def convert[T](c: Context)(in: c.Tree): Converted[c.type] =
+  private def convert[T](c: blackbox.Context)(in: c.Tree): Converted[c.type] =
     {
       val i = c.Expr[Initialize[T]](in)
       val t = c.universe.reify(i.splice).tree
       Converted.Success(t)
     }
 
-  private def failTask[C <: Context with Singleton](c: C)(pos: c.Position): Converted[c.type] =
+  private def failTask[C <: blackbox.Context with Singleton](c: C)(pos: c.Position): Converted[c.type] =
     Converted.Failure(pos, "A setting cannot depend on a task")
-  private def failPrevious[C <: Context with Singleton](c: C)(pos: c.Position): Converted[c.type] =
+  private def failPrevious[C <: blackbox.Context with Singleton](c: C)(pos: c.Position): Converted[c.type] =
     Converted.Failure(pos, "A setting cannot depend on a task's previous value.")
 }
 
 object SettingMacro {
-  def settingMacroImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[Initialize[T]] =
+  def settingMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[T]): c.Expr[Initialize[T]] =
     Instance.contImpl[T, Id](c, InitializeInstance, InitializeConvert, MixedBuilder)(Left(t), Instance.idTransform[c.type])
 
-  def settingDynMacroImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[Initialize[T]]): c.Expr[Initialize[T]] =
+  def settingDynMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[Initialize[T]]): c.Expr[Initialize[T]] =
     Instance.contImpl[T, Id](c, InitializeInstance, InitializeConvert, MixedBuilder)(Right(t), Instance.idTransform[c.type])
 }
diff --git a/main-settings/src/main/scala/sbt/std/TaskMacro.scala b/main-settings/src/main/scala/sbt/std/TaskMacro.scala
index 0841a8601..c159e0387 100644
--- a/main-settings/src/main/scala/sbt/std/TaskMacro.scala
+++ b/main-settings/src/main/scala/sbt/std/TaskMacro.scala
@@ -80,21 +80,21 @@ object TaskMacro {
       |by wrapping the expression in parenthesis, and calling `.value` at the end.
       |For example, `key := (key.dependsOn(compile in Test)).value`.""".stripMargin
 
-  def taskMacroImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[Initialize[Task[T]]] =
+  def taskMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[T]): c.Expr[Initialize[Task[T]]] =
     Instance.contImpl[T, Id](c, FullInstance, FullConvert, MixedBuilder)(Left(t), Instance.idTransform[c.type])
 
-  def taskDynMacroImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[Initialize[Task[T]]]): c.Expr[Initialize[Task[T]]] =
+  def taskDynMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[Initialize[Task[T]]]): c.Expr[Initialize[Task[T]]] =
     Instance.contImpl[T, Id](c, FullInstance, FullConvert, MixedBuilder)(Right(t), Instance.idTransform[c.type])
 
   /** Implementation of := macro for settings. */
-  def settingAssignMacroImpl[T: c.WeakTypeTag](c: Context)(v: c.Expr[T]): c.Expr[Setting[T]] =
+  def settingAssignMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[T]): c.Expr[Setting[T]] =
     {
       val init = SettingMacro.settingMacroImpl[T](c)(v)
       val assign = transformMacroImpl(c)(init.tree)(AssignInitName)
       c.Expr[Setting[T]](assign)
     }
   /** Implementation of := macro for tasks. */
-  def taskAssignMacroImpl[T: c.WeakTypeTag](c: Context)(v: c.Expr[T]): c.Expr[Setting[Task[T]]] =
+  def taskAssignMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[T]): c.Expr[Setting[Task[T]]] =
     {
       val init = taskMacroImpl[T](c)(v)
       val assign = transformMacroImpl(c)(init.tree)(AssignInitName)
@@ -104,80 +104,80 @@ object TaskMacro {
   // Error macros (Restligeist)
   // These macros are there just so we can fail old operators like `<<=` and provide useful migration information.
 
-  def fakeSettingAssignPosition[T: c.WeakTypeTag](c: Context)(app: c.Expr[Initialize[T]]): c.Expr[Setting[T]] =
+  def fakeSettingAssignPosition[T: c.WeakTypeTag](c: blackbox.Context)(app: c.Expr[Initialize[T]]): c.Expr[Setting[T]] =
     ContextUtil.selectMacroImpl[Setting[T]](c) { (ts, pos) =>
       c.abort(pos, assignMigration)
     }
-  def fakeSettingAppend1Position[S: c.WeakTypeTag, V: c.WeakTypeTag](c: Context)(v: c.Expr[Initialize[V]])(a: c.Expr[Append.Value[S, V]]): c.Expr[Setting[S]] =
+  def fakeSettingAppend1Position[S: c.WeakTypeTag, V: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[Initialize[V]])(a: c.Expr[Append.Value[S, V]]): c.Expr[Setting[S]] =
     ContextUtil.selectMacroImpl[Setting[S]](c) { (ts, pos) =>
       c.abort(pos, append1Migration)
     }
-  def fakeSettingAppendNPosition[S: c.WeakTypeTag, V: c.WeakTypeTag](c: Context)(vs: c.Expr[Initialize[V]])(a: c.Expr[Append.Values[S, V]]): c.Expr[Setting[S]] =
+  def fakeSettingAppendNPosition[S: c.WeakTypeTag, V: c.WeakTypeTag](c: blackbox.Context)(vs: c.Expr[Initialize[V]])(a: c.Expr[Append.Values[S, V]]): c.Expr[Setting[S]] =
     ContextUtil.selectMacroImpl[Setting[S]](c) { (ts, pos) =>
       c.abort(pos, appendNMigration)
     }
-  def fakeItaskAssignPosition[T: c.WeakTypeTag](c: Context)(app: c.Expr[Initialize[Task[T]]]): c.Expr[Setting[Task[T]]] =
+  def fakeItaskAssignPosition[T: c.WeakTypeTag](c: blackbox.Context)(app: c.Expr[Initialize[Task[T]]]): c.Expr[Setting[Task[T]]] =
     ContextUtil.selectMacroImpl[Setting[Task[T]]](c) { (ts, pos) =>
       c.abort(pos, assignMigration)
     }
-  def fakeTaskAppend1Position[S: c.WeakTypeTag, V: c.WeakTypeTag](c: Context)(v: c.Expr[Initialize[Task[V]]])(a: c.Expr[Append.Value[S, V]]): c.Expr[Setting[Task[S]]] =
+  def fakeTaskAppend1Position[S: c.WeakTypeTag, V: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[Initialize[Task[V]]])(a: c.Expr[Append.Value[S, V]]): c.Expr[Setting[Task[S]]] =
     ContextUtil.selectMacroImpl[Setting[Task[S]]](c) { (ts, pos) =>
       c.abort(pos, append1Migration)
     }
-  def fakeTaskAppendNPosition[S: c.WeakTypeTag, V: c.WeakTypeTag](c: Context)(vs: c.Expr[Initialize[Task[V]]])(a: c.Expr[Append.Values[S, V]]): c.Expr[Setting[Task[S]]] =
+  def fakeTaskAppendNPosition[S: c.WeakTypeTag, V: c.WeakTypeTag](c: blackbox.Context)(vs: c.Expr[Initialize[Task[V]]])(a: c.Expr[Append.Values[S, V]]): c.Expr[Setting[Task[S]]] =
     ContextUtil.selectMacroImpl[Setting[Task[S]]](c) { (ts, pos) =>
       c.abort(pos, appendNMigration)
     }
 
   /* Implementations of <<= macro variations for tasks and settings. These just get the source position of the call site.*/
 
-  def itaskAssignPosition[T: c.WeakTypeTag](c: Context)(app: c.Expr[Initialize[Task[T]]]): c.Expr[Setting[Task[T]]] =
+  def itaskAssignPosition[T: c.WeakTypeTag](c: blackbox.Context)(app: c.Expr[Initialize[Task[T]]]): c.Expr[Setting[Task[T]]] =
     settingAssignPosition(c)(app)
-  def taskAssignPositionT[T: c.WeakTypeTag](c: Context)(app: c.Expr[Task[T]]): c.Expr[Setting[Task[T]]] =
+  def taskAssignPositionT[T: c.WeakTypeTag](c: blackbox.Context)(app: c.Expr[Task[T]]): c.Expr[Setting[Task[T]]] =
     itaskAssignPosition(c)(c.universe.reify { Def.valueStrict(app.splice) })
-  def taskAssignPositionPure[T: c.WeakTypeTag](c: Context)(app: c.Expr[T]): c.Expr[Setting[Task[T]]] =
+  def taskAssignPositionPure[T: c.WeakTypeTag](c: blackbox.Context)(app: c.Expr[T]): c.Expr[Setting[Task[T]]] =
     taskAssignPositionT(c)(c.universe.reify { TaskExtra.constant(app.splice) })
-  def taskTransformPosition[S: c.WeakTypeTag](c: Context)(f: c.Expr[S => S]): c.Expr[Setting[Task[S]]] =
+  def taskTransformPosition[S: c.WeakTypeTag](c: blackbox.Context)(f: c.Expr[S => S]): c.Expr[Setting[Task[S]]] =
     c.Expr[Setting[Task[S]]](transformMacroImpl(c)(f.tree)(TransformInitName))
-  def settingTransformPosition[S: c.WeakTypeTag](c: Context)(f: c.Expr[S => S]): c.Expr[Setting[S]] =
+  def settingTransformPosition[S: c.WeakTypeTag](c: blackbox.Context)(f: c.Expr[S => S]): c.Expr[Setting[S]] =
     c.Expr[Setting[S]](transformMacroImpl(c)(f.tree)(TransformInitName))
-  def itaskTransformPosition[S: c.WeakTypeTag](c: Context)(f: c.Expr[S => S]): c.Expr[Setting[S]] =
+  def itaskTransformPosition[S: c.WeakTypeTag](c: blackbox.Context)(f: c.Expr[S => S]): c.Expr[Setting[S]] =
     c.Expr[Setting[S]](transformMacroImpl(c)(f.tree)(TransformInitName))
-  def settingAssignPure[T: c.WeakTypeTag](c: Context)(app: c.Expr[T]): c.Expr[Setting[T]] =
+  def settingAssignPure[T: c.WeakTypeTag](c: blackbox.Context)(app: c.Expr[T]): c.Expr[Setting[T]] =
     settingAssignPosition(c)(c.universe.reify { Def.valueStrict(app.splice) })
-  def settingAssignPosition[T: c.WeakTypeTag](c: Context)(app: c.Expr[Initialize[T]]): c.Expr[Setting[T]] =
+  def settingAssignPosition[T: c.WeakTypeTag](c: blackbox.Context)(app: c.Expr[Initialize[T]]): c.Expr[Setting[T]] =
     c.Expr[Setting[T]](transformMacroImpl(c)(app.tree)(AssignInitName))
 
   /** Implementation of := macro for tasks. */
-  def inputTaskAssignMacroImpl[T: c.WeakTypeTag](c: Context)(v: c.Expr[T]): c.Expr[Setting[InputTask[T]]] =
+  def inputTaskAssignMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[T]): c.Expr[Setting[InputTask[T]]] =
     {
       val init = inputTaskMacroImpl[T](c)(v)
       val assign = transformMacroImpl(c)(init.tree)(AssignInitName)
       c.Expr[Setting[InputTask[T]]](assign)
     }
   /** Implementation of += macro for tasks. */
-  def taskAppend1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(v: c.Expr[U])(a: c.Expr[Append.Value[T, U]]): c.Expr[Setting[Task[T]]] =
+  def taskAppend1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[U])(a: c.Expr[Append.Value[T, U]]): c.Expr[Setting[Task[T]]] =
     {
       val init = taskMacroImpl[U](c)(v)
       val append = appendMacroImpl(c)(init.tree, a.tree)(Append1InitName)
       c.Expr[Setting[Task[T]]](append)
     }
   /** Implementation of += macro for settings. */
-  def settingAppend1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(v: c.Expr[U])(a: c.Expr[Append.Value[T, U]]): c.Expr[Setting[T]] =
+  def settingAppend1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[U])(a: c.Expr[Append.Value[T, U]]): c.Expr[Setting[T]] =
     {
       val init = SettingMacro.settingMacroImpl[U](c)(v)
       val append = appendMacroImpl(c)(init.tree, a.tree)(Append1InitName)
       c.Expr[Setting[T]](append)
     }
   /** Implementation of ++= macro for tasks. */
-  def taskAppendNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(vs: c.Expr[U])(a: c.Expr[Append.Values[T, U]]): c.Expr[Setting[Task[T]]] =
+  def taskAppendNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(vs: c.Expr[U])(a: c.Expr[Append.Values[T, U]]): c.Expr[Setting[Task[T]]] =
     {
       val init = taskMacroImpl[U](c)(vs)
       val append = appendMacroImpl(c)(init.tree, a.tree)(AppendNInitName)
       c.Expr[Setting[Task[T]]](append)
     }
   /** Implementation of ++= macro for settings. */
-  def settingAppendNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(vs: c.Expr[U])(a: c.Expr[Append.Values[T, U]]): c.Expr[Setting[T]] =
+  def settingAppendNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(vs: c.Expr[U])(a: c.Expr[Append.Values[T, U]]): c.Expr[Setting[T]] =
     {
       val init = SettingMacro.settingMacroImpl[U](c)(vs)
       val append = appendMacroImpl(c)(init.tree, a.tree)(AppendNInitName)
@@ -185,35 +185,35 @@ object TaskMacro {
     }
 
   /** Implementation of -= macro for tasks. */
-  def taskRemove1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(v: c.Expr[U])(r: c.Expr[Remove.Value[T, U]]): c.Expr[Setting[Task[T]]] =
+  def taskRemove1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[U])(r: c.Expr[Remove.Value[T, U]]): c.Expr[Setting[Task[T]]] =
     {
       val init = taskMacroImpl[U](c)(v)
       val remove = removeMacroImpl(c)(init.tree, r.tree)(Remove1InitName)
       c.Expr[Setting[Task[T]]](remove)
     }
   /** Implementation of -= macro for settings. */
-  def settingRemove1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(v: c.Expr[U])(r: c.Expr[Remove.Value[T, U]]): c.Expr[Setting[T]] =
+  def settingRemove1Impl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(v: c.Expr[U])(r: c.Expr[Remove.Value[T, U]]): c.Expr[Setting[T]] =
     {
       val init = SettingMacro.settingMacroImpl[U](c)(v)
       val remove = removeMacroImpl(c)(init.tree, r.tree)(Remove1InitName)
       c.Expr[Setting[T]](remove)
     }
   /** Implementation of --= macro for tasks. */
-  def taskRemoveNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(vs: c.Expr[U])(r: c.Expr[Remove.Values[T, U]]): c.Expr[Setting[Task[T]]] =
+  def taskRemoveNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(vs: c.Expr[U])(r: c.Expr[Remove.Values[T, U]]): c.Expr[Setting[Task[T]]] =
     {
       val init = taskMacroImpl[U](c)(vs)
       val remove = removeMacroImpl(c)(init.tree, r.tree)(RemoveNInitName)
       c.Expr[Setting[Task[T]]](remove)
     }
   /** Implementation of --= macro for settings. */
-  def settingRemoveNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: Context)(vs: c.Expr[U])(r: c.Expr[Remove.Values[T, U]]): c.Expr[Setting[T]] =
+  def settingRemoveNImpl[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(vs: c.Expr[U])(r: c.Expr[Remove.Values[T, U]]): c.Expr[Setting[T]] =
     {
       val init = SettingMacro.settingMacroImpl[U](c)(vs)
       val remove = removeMacroImpl(c)(init.tree, r.tree)(RemoveNInitName)
       c.Expr[Setting[T]](remove)
     }
 
-  private[this] def appendMacroImpl(c: Context)(init: c.Tree, append: c.Tree)(newName: String): c.Tree =
+  private[this] def appendMacroImpl(c: blackbox.Context)(init: c.Tree, append: c.Tree)(newName: String): c.Tree =
     {
       import c.universe._
       c.macroApplication match {
@@ -222,7 +222,7 @@ object TaskMacro {
         case x => ContextUtil.unexpectedTree(x)
       }
     }
-  private[this] def removeMacroImpl(c: Context)(init: c.Tree, remove: c.Tree)(newName: String): c.Tree =
+  private[this] def removeMacroImpl(c: blackbox.Context)(init: c.Tree, remove: c.Tree)(newName: String): c.Tree =
     {
       import c.universe._
       c.macroApplication match {
@@ -231,7 +231,7 @@ object TaskMacro {
         case x => ContextUtil.unexpectedTree(x)
       }
     }
-  private[this] def transformMacroImpl(c: Context)(init: c.Tree)(newName: String): c.Tree =
+  private[this] def transformMacroImpl(c: blackbox.Context)(init: c.Tree)(newName: String): c.Tree =
     {
       import c.universe._
       val target =
@@ -241,7 +241,7 @@ object TaskMacro {
         }
       Apply.apply(Select(target, TermName(newName).encodedName), init :: sourcePosition(c).tree :: Nil)
     }
-  private[this] def sourcePosition(c: Context): c.Expr[SourcePosition] =
+  private[this] def sourcePosition(c: blackbox.Context): c.Expr[SourcePosition] =
     {
       import c.universe.reify
       val pos = c.enclosingPosition
@@ -253,7 +253,7 @@ object TaskMacro {
       } else
         reify { NoPosition }
     }
-  private[this] def settingSource(c: Context, path: String, name: String): String =
+  private[this] def settingSource(c: blackbox.Context, path: String, name: String): String =
     {
       @tailrec def inEmptyPackage(s: c.Symbol): Boolean = s != c.universe.NoSymbol && (
         s.owner == c.mirror.EmptyPackage || s.owner == c.mirror.EmptyPackageClass || inEmptyPackage(s.owner)
@@ -265,17 +265,17 @@ object TaskMacro {
       }
     }
 
-  private[this] def constant[T: c.TypeTag](c: Context, t: T): c.Expr[T] = {
+  private[this] def constant[T: c.TypeTag](c: blackbox.Context, t: T): c.Expr[T] = {
     import c.universe._
     c.Expr[T](Literal(Constant(t)))
   }
 
-  def inputTaskMacroImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[Initialize[InputTask[T]]] =
+  def inputTaskMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[T]): c.Expr[Initialize[InputTask[T]]] =
     inputTaskMacro0[T](c)(t)
-  def inputTaskDynMacroImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[Initialize[Task[T]]]): c.Expr[Initialize[InputTask[T]]] =
+  def inputTaskDynMacroImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[Initialize[Task[T]]]): c.Expr[Initialize[InputTask[T]]] =
     inputTaskDynMacro0[T](c)(t)
 
-  private[this] def inputTaskMacro0[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[Initialize[InputTask[T]]] =
+  private[this] def inputTaskMacro0[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[T]): c.Expr[Initialize[InputTask[T]]] =
     iInitializeMacro(c)(t) { et =>
       val pt = iParserMacro(c)(et) { pt =>
         iTaskMacro(c)(pt)
@@ -283,13 +283,13 @@ object TaskMacro {
       c.universe.reify { InputTask.make(pt.splice) }
     }
 
-  private[this] def iInitializeMacro[M[_], T](c: Context)(t: c.Expr[T])(f: c.Expr[T] => c.Expr[M[T]])(implicit tt: c.WeakTypeTag[T], mt: c.WeakTypeTag[M[T]]): c.Expr[Initialize[M[T]]] =
+  private[this] def iInitializeMacro[M[_], T](c: blackbox.Context)(t: c.Expr[T])(f: c.Expr[T] => c.Expr[M[T]])(implicit tt: c.WeakTypeTag[T], mt: c.WeakTypeTag[M[T]]): c.Expr[Initialize[M[T]]] =
     {
       val inner: Transform[c.type, M] = new Transform[c.type, M] { def apply(in: c.Tree): c.Tree = f(c.Expr[T](in)).tree }
       val cond = c.Expr[T](conditionInputTaskTree(c)(t.tree))
       Instance.contImpl[T, M](c, InitializeInstance, InputInitConvert, MixedBuilder)(Left(cond), inner)
     }
-  private[this] def conditionInputTaskTree(c: Context)(t: c.Tree): c.Tree =
+  private[this] def conditionInputTaskTree(c: blackbox.Context)(t: c.Tree): c.Tree =
     {
       import c.universe._
       import InputWrapper._
@@ -326,16 +326,16 @@ object TaskMacro {
       util.transformWrappers(t, (nme, tpe, tree, original) => expand(nme, tpe, tree))
     }
 
-  private[this] def iParserMacro[M[_], T](c: Context)(t: c.Expr[T])(f: c.Expr[T] => c.Expr[M[T]])(implicit tt: c.WeakTypeTag[T], mt: c.WeakTypeTag[M[T]]): c.Expr[State => Parser[M[T]]] =
+  private[this] def iParserMacro[M[_], T](c: blackbox.Context)(t: c.Expr[T])(f: c.Expr[T] => c.Expr[M[T]])(implicit tt: c.WeakTypeTag[T], mt: c.WeakTypeTag[M[T]]): c.Expr[State => Parser[M[T]]] =
     {
       val inner: Transform[c.type, M] = new Transform[c.type, M] { def apply(in: c.Tree): c.Tree = f(c.Expr[T](in)).tree }
       Instance.contImpl[T, M](c, ParserInstance, ParserConvert, MixedBuilder)(Left(t), inner)
     }
 
-  private[this] def iTaskMacro[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[Task[T]] =
+  private[this] def iTaskMacro[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[T]): c.Expr[Task[T]] =
     Instance.contImpl[T, Id](c, TaskInstance, TaskConvert, MixedBuilder)(Left(t), Instance.idTransform)
 
-  private[this] def inputTaskDynMacro0[T: c.WeakTypeTag](c: Context)(t: c.Expr[Initialize[Task[T]]]): c.Expr[Initialize[InputTask[T]]] =
+  private[this] def inputTaskDynMacro0[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[Initialize[Task[T]]]): c.Expr[Initialize[InputTask[T]]] =
     {
       import c.universe.{ Apply => ApplyTree, _ }
       import internal.decorators._
@@ -417,10 +417,10 @@ object TaskMacro {
 
 object PlainTaskMacro {
   def task[T](t: T): Task[T] = macro taskImpl[T]
-  def taskImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[Task[T]] =
+  def taskImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[T]): c.Expr[Task[T]] =
     Instance.contImpl[T, Id](c, TaskInstance, TaskConvert, MixedBuilder)(Left(t), Instance.idTransform[c.type])
 
   def taskDyn[T](t: Task[T]): Task[T] = macro taskDynImpl[T]
-  def taskDynImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[Task[T]]): c.Expr[Task[T]] =
+  def taskDynImpl[T: c.WeakTypeTag](c: blackbox.Context)(t: c.Expr[Task[T]]): c.Expr[Task[T]] =
     Instance.contImpl[T, Id](c, TaskInstance, TaskConvert, MixedBuilder)(Right(t), Instance.idTransform[c.type])
 }
diff --git a/main/src/main/scala/sbt/Project.scala b/main/src/main/scala/sbt/Project.scala
index f02fec3c2..dce3233e5 100755
--- a/main/src/main/scala/sbt/Project.scala
+++ b/main/src/main/scala/sbt/Project.scala
@@ -636,7 +636,7 @@ object Project extends ProjectExtra {
 
   import reflect.macros._
 
-  def projectMacroImpl(c: Context): c.Expr[Project] =
+  def projectMacroImpl(c: blackbox.Context): c.Expr[Project] =
     {
       import c.universe._
       val enclosingValName = std.KeyMacro.definingValName(c, methodName => s"""$methodName must be directly assigned to a val, such as `val x = $methodName`. Alternatively, you can use `sbt.Project.apply`""")