Makes ExpandWhens preserve connect Infos

* Collects Infos found for symbols
* Merges multiple sources for symbol into MultiInfo
* Restores these Infos on connect statements.
* Add test showing preserved Infos
* Changed ++ methods on the Info sub-classes
  * Ignore NoInfo being added
  * Fixed way adding was implemented in MultiInfo
* Made InfoMap a class which defines the default value function

1 files changed, 4 insertions, 2 deletions

diff --git a/src/main/scala/firrtl/ir/IR.scala b/src/main/scala/firrtl/ir/IR.scala
index 53fbb765..3887f17d 100644
--- a/src/main/scala/firrtl/ir/IR.scala
+++ b/src/main/scala/firrtl/ir/IR.scala
@@ -21,7 +21,8 @@ case object NoInfo extends Info {
 }
 case class FileInfo(info: StringLit) extends Info {
   override def toString: String = " @[" + info.serialize + "]"
-  def ++(that: Info): Info = MultiInfo(Seq(this, that))
+  //scalastyle:off method.name
+  def ++(that: Info): Info = if (that == NoInfo) this else MultiInfo(Seq(this, that))
 }
 case class MultiInfo(infos: Seq[Info]) extends Info {
   private def collectStringLits(info: Info): Seq[StringLit] = info match {
@@ -34,7 +35,8 @@ case class MultiInfo(infos: Seq[Info]) extends Info {
     if (parts.nonEmpty) parts.map(_.serialize).mkString(" @[", " ", "]")
     else ""
   }
-  def ++(that: Info): Info = MultiInfo(Seq(this, that))
+  //scalastyle:off method.name
+  def ++(that: Info): Info = if (that == NoInfo) this else MultiInfo(infos :+ that)
 }
 object MultiInfo {
   def apply(infos: Info*) = {