Make Module and Bundle properly use empty namespaces

Fix default suggested name of Module instances (now based on desired name
rather than actual assigned name).
Remove parent/child relationship from Namespace.

Previously, Module and Bundle namespaces were "children" of the Module
definition namespace. This could lead to collisions that would give unexpected
names for module instances or Bundle elements. In particular, otherwise
identical modules that instantiate other identical modules in such a way that
the instance cannot be named via reflection would not be deduplicated because
the names of the instances would collide with the names of the modules in the
Builder.globalNamespace.

1 files changed, 7 insertions, 7 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
index 5d841941..d8202da6 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
@@ -9,7 +9,7 @@ import chisel3._
 import core._
 import firrtl._
 
-private[chisel3] class Namespace(parent: Option[Namespace], keywords: Set[String]) {
+private[chisel3] class Namespace(keywords: Set[String]) {
   private val names = collection.mutable.HashMap[String, Long]()
   for (keyword <- keywords)
     names(keyword) = 1
@@ -29,9 +29,7 @@ private[chisel3] class Namespace(parent: Option[Namespace], keywords: Set[String
     if (res.isEmpty || !legalStart(res.head)) s"_$res" else res
   }
 
-  def contains(elem: String): Boolean = {
-    names.contains(elem) || parent.map(_ contains elem).getOrElse(false)
-  }
+  def contains(elem: String): Boolean = names.contains(elem)
 
   def name(elem: String): String = {
     val sanitized = sanitize(elem)
@@ -42,9 +40,11 @@ private[chisel3] class Namespace(parent: Option[Namespace], keywords: Set[String
       sanitized
     }
   }
+}
 
-  def child(kws: Set[String]): Namespace = new Namespace(Some(this), kws)
-  def child: Namespace = child(Set())
+private[chisel3] object Namespace {
+  /** Constructs an empty Namespace */
+  def empty: Namespace = new Namespace(Set.empty[String])
 }
 
 private[chisel3] class IdGen {
@@ -143,7 +143,7 @@ private[chisel3] trait HasId extends InstanceId {
 
 private[chisel3] class DynamicContext() {
   val idGen = new IdGen
-  val globalNamespace = new Namespace(None, Set())
+  val globalNamespace = Namespace.empty
   val components = ArrayBuffer[Component]()
   val annotations = ArrayBuffer[ChiselAnnotation]()
   var currentModule: Option[Module] = None