2 files changed, 15 insertions, 1 deletions
diff --git a/stage2/BasicBuild.scala b/stage2/BasicBuild.scala
index d8d1b8b..3ce9ed1 100644
--- a/stage2/BasicBuild.scala
+++ b/stage2/BasicBuild.scala
@@ -18,8 +18,17 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with Trigge
   def enableConcurrency = false
   final def projectDirectory: File = lib.realpath(context.projectDirectory)
   assert( projectDirectory.exists, "projectDirectory does not exist: " ++ projectDirectory.string )
+  assert(
+    projectDirectory.getName =!= "build" ||
+    {
+      def transitiveInterfaces(cls: Class[_]): Vector[Class[_]] = cls.getInterfaces.toVector.flatMap(i => i +: transitiveInterfaces(i))
+      transitiveInterfaces(this.getClass).contains(classOf[BuildBuildWithoutEssentials])
+    },
+    "You need to extend BuildBuild in: " + projectDirectory + "/build"
+  )
+
   final def usage: String = lib.usage(this.getClass, show)
-  
+
   final def taskNames: String = lib.taskNames(this.getClass).sorted.mkString("\n")
 
   // ========== meta data ==========
diff --git a/stage2/BuildBuild.scala b/stage2/BuildBuild.scala
index 5eb7622..0736e7e 100644
--- a/stage2/BuildBuild.scala
+++ b/stage2/BuildBuild.scala
@@ -6,6 +6,11 @@ trait BuildBuild extends BuildBuildWithoutEssentials{
     super.dependencies :+ plugins.essentials
 }
 trait BuildBuildWithoutEssentials extends BaseBuild{
+  assert(
+    projectDirectory.getName === "build",
+    "You can't extend BuildBuild in: " + projectDirectory + "/build"
+  )
+
   protected final val managedContext = context.copy(
     projectDirectory = managedBuildDirectory,
     parentBuild=Some(this)