Add WireInit.apply that accepts DontCare (#731)

Prevents DontCare from affecting type inference
Fixes #728

2 files changed, 24 insertions, 0 deletions

diff --git a/src/main/scala/chisel3/package.scala b/src/main/scala/chisel3/package.scala
index f31b4015..a502ef2d 100644
--- a/src/main/scala/chisel3/package.scala
+++ b/src/main/scala/chisel3/package.scala
@@ -32,6 +32,10 @@ package object chisel3 {    // scalastyle:ignore package.object.name
     @deprecated("Wire(t, init) is deprecated, use WireInit(t, init) instead", "chisel3")
     def apply[T <: Data](t: T, init: T)(implicit compileOptions: CompileOptions): T =
       chisel3.core.WireInit(t, init)
+
+    @deprecated("Wire(t, init) is deprecated, use WireInit(t, init) instead", "chisel3")
+    def apply[T <: Data](t: T, init: DontCare.type)(implicit compileOptions: CompileOptions): T =
+      chisel3.core.WireInit(t, init)
   }
   val WireInit = chisel3.core.WireInit
 
diff --git a/src/test/scala/chiselTests/WireSpec.scala b/src/test/scala/chiselTests/WireSpec.scala
new file mode 100644
index 00000000..051880ee
--- /dev/null
+++ b/src/test/scala/chiselTests/WireSpec.scala
@@ -0,0 +1,20 @@
+// See LICENSE for license details.
+
+package chiselTests
+
+import chisel3._
+
+class WireSpec extends ChiselFlatSpec {
+  "WireInit.apply" should "work" in {
+    assertCompiles("WireInit(UInt(4.W), 2.U)")
+  }
+  it should "allow DontCare" in {
+    assertCompiles("WireInit(UInt(4.W), DontCare)")
+  }
+  it should "not allow DontCare to affect type inference" in {
+    assertCompiles("val x: UInt = WireInit(UInt(4.W), DontCare)")
+  }
+  it should "not allow init argument to affect type inference" in {
+    assertDoesNotCompile("val x: UInt = WireInit(UInt(4.W), 2.S)")
+  }
+}