Add ValidIO definition for old code.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/main/scala/chisel3/package.scala b/src/main/scala/chisel3/package.scala
index 774455c4..926ca00d 100644
--- a/src/main/scala/chisel3/package.scala
+++ b/src/main/scala/chisel3/package.scala
@@ -111,8 +111,10 @@ package object chisel3 {
     def do_=/= (that: BitPat)(implicit sourceInfo: SourceInfo): Bool = that =/= x
   }
 
+  // Compatibility with existing code.
   val INPUT = chisel3.core.Direction.Input
   val OUTPUT = chisel3.core.Direction.Output
   val NODIR = chisel3.core.Direction.Unspecified
   type ChiselException = chisel3.internal.ChiselException
+  type ValidIO[+T <: Data] = chisel3.util.Valid[T]
 }