Use Data refs for name prefixing with aggregate elements (#1616)

* Use Data refs for name prefixing with aggregate elements

Vecs set the refs of their elements upon construction of those elements.
In the past, Records haven't set their elements refs until module close,
but it can be done sooner. Doing it upon binding means that refs will at
least be available for Records used in hardware elements. Since only
bound Data can be connected to anyway, Aggregate elements being
connected to will always have a ref which we can then use for creating
naming prefixes.

* Add tighter correctness checks

* Handle more cases in connection prefixing

Add support for forcing setRef to override a previous setting. This
is only used by BlackBox ports which need to drop their io prefix.

Also add a Try() around Data.bindingToString which sometimes throws
exceptions when being used to .toString a Data in an error message.

* Strip trailing spaces in names in compiler plugin

1 files changed, 4 insertions, 2 deletions

diff --git a/core/src/main/scala/chisel3/Data.scala b/core/src/main/scala/chisel3/Data.scala
index bb45b4d8..5d398aa6 100644
--- a/core/src/main/scala/chisel3/Data.scala
+++ b/core/src/main/scala/chisel3/Data.scala
@@ -9,6 +9,8 @@ import chisel3.internal._
 import chisel3.internal.firrtl._
 import chisel3.internal.sourceinfo.{DeprecatedSourceInfo, SourceInfo, SourceInfoTransform, UnlocatableSourceInfo}
 
+import scala.util.Try
+
 /** User-specified directions.
   */
 sealed abstract class SpecifiedDirection
@@ -374,7 +376,7 @@ abstract class Data extends HasId with NamedComponent with SourceInfoDoc {
   // Provides a unhelpful fallback for literals, which should have custom rendering per
   // Data-subtype.
   // TODO Is this okay for sample_element? It *shouldn't* be visible to users
-  protected def bindingToString: String = topBindingOpt match {
+  protected def bindingToString: String = Try(topBindingOpt match {
     case None => ""
     case Some(OpBinding(enclosure, _)) => s"(OpResult in ${enclosure.desiredName})"
     case Some(MemoryPortBinding(enclosure, _)) => s"(MemPort in ${enclosure.desiredName})"
@@ -389,7 +391,7 @@ abstract class Data extends HasId with NamedComponent with SourceInfoDoc {
     case Some(DontCareBinding()) => s"(DontCare)"
     case Some(ElementLitBinding(litArg)) => s"(unhandled literal)"
     case Some(BundleLitBinding(litMap)) => s"(unhandled bundle literal)"
-  }
+  }).getOrElse("")
 
   // Return ALL elements at root of this type.
   // Contasts with flatten, which returns just Bits