`aggregate` can now be used inside a .sbt file (#2683)

(cherry picked from commit b92e5773f7)

main/src/main/scala/sbt/internal/DslAst.scala

@@ -1,7 +1,7 @@
 package sbt
 package internal
 
-import sbt.internal.util.RangePosition
+import sbt.internal.util.{ Eval, RangePosition }
 
 import sbt.librarymanagement.Configuration
 
@@ -61,5 +61,8 @@ object DslEntry {
   case class DslConfigs(cs: Seq[Configuration]) extends ProjectManipulation {
     override val toFunction: Project => Project = _.configs(cs: _*)
   }
-
+  /** this represents an `aggregate()` in the sbt DSL */
+  case class DslAggregate(refs: Seq[Eval[ProjectReference]]) extends ProjectManipulation {
+    override val toFunction: Project => Project = _.aggregate(refs: _*)
+  }
 }

notes/1.0.0/aggregate-build-sbt.md

@@ -0,0 +1,5 @@
+  [@xuwei-k]: https://github.com/xuwei-k
+
+### Improvements
+
+- Add the ability to call aggregate for the current project inside a build sbt file. By [@xuwei-k][@xuwei-k]

sbt/src/main/scala/syntax.scala

@@ -1,6 +1,7 @@
 package sbt
 
 import sbt.internal.DslEntry
+import sbt.internal.util.Eval
 
 object syntax extends syntax
 
@@ -51,6 +52,8 @@ abstract class syntax extends IOSyntax0 with sbt.std.TaskExtra with sbt.internal
   def enablePlugins(ps: AutoPlugin*): DslEntry = DslEntry.DslEnablePlugins(ps)
   def disablePlugins(ps: AutoPlugin*): DslEntry = DslEntry.DslDisablePlugins(ps)
   def configs(cs: Configuration*): DslEntry = DslEntry.DslConfigs(cs)
+  // avoid conflict with `sbt.Keys.aggregate`
+  def aggregateProjects(refs: Eval[ProjectReference]*): DslEntry = DslEntry.DslAggregate(refs)
 }
 
 // Todo share this this io.syntax

sbt/src/sbt-test/project/aggregate/build.sbt

@@ -0,0 +1,3 @@
+aggregateProjects(
+  RootProject(file("projA"))
+)

sbt/src/sbt-test/project/aggregate/projA/A.scala

@@ -0,0 +1 @@
+class A

sbt/src/sbt-test/project/aggregate/projA/build.sbt

@@ -0,0 +1,3 @@
+name := "projA"
+
+scalaVersion := "2.11.8"

sbt/src/sbt-test/project/aggregate/test

@@ -0,0 +1,2 @@
+> compile
+$ exists projA/target/scala-2.11/classes/A.class