Support DontCare in Mux and cloneSupertype (#995)

2 files changed, 34 insertions, 0 deletions

diff --git a/src/test/scala/chiselTests/MuxSpec.scala b/src/test/scala/chiselTests/MuxSpec.scala
new file mode 100644
index 00000000..d06c00af
--- /dev/null
+++ b/src/test/scala/chiselTests/MuxSpec.scala
@@ -0,0 +1,25 @@
+package chiselTests
+
+import chisel3._
+import chisel3.testers.BasicTester
+
+class MuxTester extends BasicTester {
+  assert(Mux(0.B, 1.U, 2.U) === 2.U)
+  assert(Mux(1.B, 1.U, 2.U) === 1.U)
+  val dontCareMux1 = Wire(UInt())
+  dontCareMux1 := Mux(0.B, DontCare, 4.U)  // note: Mux output of type Element
+  assert(dontCareMux1 === 4.U)
+
+  val dontCareMux2 = Wire(UInt())
+  dontCareMux2 := Mux(1.B, 3.U, DontCare)  // note: Mux output of type Element
+  assert(dontCareMux2 === 3.U)
+
+  Mux(0.B, 3.U, DontCare)  // just to make sure nothing crashes, any result is valid
+  stop()
+}
+
+class MuxSpec extends ChiselFlatSpec {
+  "Mux" should "pass basic checks" in {
+    assertTesterPasses { new MuxTester }
+  }
+}
\ No newline at end of file
diff --git a/src/test/scala/chiselTests/Vec.scala b/src/test/scala/chiselTests/Vec.scala
index 395624f7..d8e3be10 100644
--- a/src/test/scala/chiselTests/Vec.scala
+++ b/src/test/scala/chiselTests/Vec.scala
@@ -265,4 +265,13 @@ class VecSpec extends ChiselPropSpec {
       })
     }
   }
+
+  property("It should be possible to initialize a Vec with DontCare") {
+    elaborate(new Module {
+      val io = IO(new Bundle {
+        val out = Output(Vec(4, UInt(8.W)))
+      })
+      io.out := VecInit(Seq(4.U, 5.U, DontCare, 2.U))
+    })
+  }
 }