Make Bits.toBool safe

It now fails if the width is unknown or is not equal to 1.
We could consider relaxing this later, defining it as this.orR.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/main/scala/Chisel/Core.scala b/src/main/scala/Chisel/Core.scala
index 4b8d2ca3..1ab84681 100644
--- a/src/main/scala/Chisel/Core.scala
+++ b/src/main/scala/Chisel/Core.scala
@@ -639,7 +639,11 @@ sealed abstract class Bits(dirArg: Direction, width: Width, override val litArg:
   def asUInt(): UInt
   final def toSInt(): SInt = asSInt
   final def toUInt(): UInt = asUInt
-  def toBool(): Bool = this(0)
+
+  def toBool(): Bool = width match {
+    case KnownWidth(1) => this(0)
+    case _ => throwException(s"can't covert UInt<$width> to Bool")
+  }
 
   override def toBits = asUInt
   override def fromBits(n: Bits): this.type = {