Add support for parameterized BlackBoxes

Also restrict black boxes to not allow hardware inside of them since it was
being silently dropped anyway.

Resolves #289

1 files changed, 4 insertions, 1 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
index 028ce628..60ce6d5d 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
@@ -181,7 +181,10 @@ private[chisel3] object Builder {
   // TODO(twigg): Ideally, binding checks and new bindings would all occur here
   // However, rest of frontend can't support this yet.
   def pushCommand[T <: Command](c: T): T = {
-    forcedModule._commands += c
+    forcedModule match {
+      case _: BlackBox => throwException("Cannot add hardware to a BlackBox")
+      case m => m._commands += c
+    }
     c
   }
   def pushOp[T <: Data](cmd: DefPrim[T]): T = {