Support := views to DontCare (#2536) (#2539)

(cherry picked from commit 77a6c93592d5766d66f199720fc6d69478005091)

Co-authored-by: Jack Koenig <koenig@sifive.com>

2 files changed, 22 insertions, 1 deletions

diff --git a/core/src/main/scala/chisel3/internal/MonoConnect.scala b/core/src/main/scala/chisel3/internal/MonoConnect.scala
index 40056c89..31364804 100644
--- a/core/src/main/scala/chisel3/internal/MonoConnect.scala
+++ b/core/src/main/scala/chisel3/internal/MonoConnect.scala
@@ -210,7 +210,9 @@ private[chisel3] object MonoConnect {
         }
 
       // Source is DontCare - it may be connected to anything. It generates a defInvalid for the sink.
-      case (sink, DontCare) => pushCommand(DefInvalid(sourceInfo, sink.lref))
+      case (_sink: Element, DontCare) =>
+        val sink = reify(_sink) // Handle views
+        pushCommand(DefInvalid(sourceInfo, sink.lref))
       // DontCare as a sink is illegal.
       case (DontCare, _) => throw DontCareCantBeSink
       // Analog is illegal in mono connections.
diff --git a/src/test/scala/chiselTests/experimental/DataView.scala b/src/test/scala/chiselTests/experimental/DataView.scala
index e7caacfd..ac8357f0 100644
--- a/src/test/scala/chiselTests/experimental/DataView.scala
+++ b/src/test/scala/chiselTests/experimental/DataView.scala
@@ -479,6 +479,25 @@ class DataViewSpec extends ChiselFlatSpec {
     (err.getMessage should fullyMatch).regex(expected)
   }
 
+  it should "support invalidation" in {
+    class MyModule extends Module {
+      val a, b, c, d, e, f = IO(Output(UInt(8.W)))
+      val foo = (a, b).viewAs
+      val bar = (c, d).viewAs
+      val fizz = (e, f).viewAs
+      foo := DontCare
+      bar <> DontCare
+      fizz._1 := DontCare
+      fizz._2 <> DontCare
+    }
+
+    val chirrtl = ChiselStage.emitChirrtl(new MyModule)
+    val expected = ('a' to 'f').map(c => s"$c is invalid")
+    for (line <- expected) {
+      chirrtl should include(line)
+    }
+  }
+
   behavior.of("PartialDataView")
 
   it should "still error if the mapping is non-total in the view" in {