fix updated headers of if and match to have reachable types

Author: Oron Port

core/src/main/scala/dfhdl/core/DFIf.scala

@@ -114,7 +114,7 @@ object DFIf:
     if (hasNoType || branchTypes.forall(_.isSimilarTo(branchTypes.head)))
       val retDFType = if (hasNoType) ir.DFUnit else branchTypes.head
       val DFVal(headerIR: DFIfHeader) = header: @unchecked
-      val headerUpdate = headerIR.copy(dfType = retDFType)
+      val headerUpdate = headerIR.copy(dfType = retDFType.dropUnreachableRefs)
       // updating the type of the if header
       headerIR.replaceMemberWith(headerUpdate).asValAny.asInstanceOf[R]
     else // violation

core/src/main/scala/dfhdl/core/DFMatch.scala

@@ -84,7 +84,7 @@ object DFMatch:
         case DFUnit => firstCaseRet.get
         case _ =>
           val DFVal(headerIR: DFMatchHeader) = header: @unchecked
-          val headerUpdate = headerIR.copy(dfType = retDFType.asIR)
+          val headerUpdate = headerIR.copy(dfType = retDFType.asIR.dropUnreachableRefs)
           // updating the type of the match header
           headerIR.replaceMemberWith(headerUpdate).asValAny.asInstanceOf[R]
     else

lib/src/test/scala/docExamples/ugdemos/demo5/LRShiftDirect.scala

@@ -53,7 +53,7 @@ enum ShiftDir extends Encode:
   lshifter.shift <> shift
   rshifter.iBits <> iBits
   rshifter.shift <> shift
-  dir match
-    case ShiftDir.Left  => oBits := lshifter.oBits
-    case ShiftDir.Right => oBits := rshifter.oBits
+  oBits := dir match
+    case ShiftDir.Left  => lshifter.oBits
+    case ShiftDir.Right => rshifter.oBits
 end LRShiftDirect