Add ability to suppress enum cast warnings (#2671) (#2674)

(cherry picked from commit 1ad820f7f549eddcd7188b737f59a240e48a7f0a)

Co-authored-by: Zachary Yedidia <zyedidia@gmail.com>

2 files changed, 35 insertions, 1 deletions

diff --git a/core/src/main/scala/chisel3/StrongEnum.scala b/core/src/main/scala/chisel3/StrongEnum.scala
index cd6f11ee..6d8ceb2f 100644
--- a/core/src/main/scala/chisel3/StrongEnum.scala
+++ b/core/src/main/scala/chisel3/StrongEnum.scala
@@ -339,7 +339,7 @@ abstract class EnumFactory {
     } else if (n.getWidth > this.getWidth) {
       throwException(s"The UInt being cast to $enumTypeName is wider than $enumTypeName's width ($getWidth)")
     } else {
-      if (warn && !this.isTotal) {
+      if (!Builder.suppressEnumCastWarning && warn && !this.isTotal) {
         Builder.warning(
           s"Casting non-literal UInt to $enumTypeName. You can use $enumTypeName.safe to cast without this warning."
         )
@@ -409,3 +409,33 @@ private[chisel3] class UnsafeEnum(override val width: Width) extends EnumType(Un
   override def cloneType: this.type = new UnsafeEnum(width).asInstanceOf[this.type]
 }
 private object UnsafeEnum extends EnumFactory
+
+/** Suppress enum cast warnings
+  *
+  * Users should use [[EnumFactory.safe <EnumType>.safe]] when possible.
+  *
+  * This is primarily used for casting from [[UInt]] to a Bundle type that contains an Enum.
+  * {{{
+  * class MyBundle extends Bundle {
+  *   val addr = UInt(8.W)
+  *   val op = OpEnum()
+  * }
+  *
+  * // Since this is a cast to a Bundle, cannot use OpCode.safe
+  * val bundle = suppressEnumCastWarning {
+  *   someUInt.asTypeOf(new MyBundle)
+  * }
+  * }}}
+  */
+object suppressEnumCastWarning {
+  def apply[T](block: => T): T = {
+    val parentWarn = Builder.suppressEnumCastWarning
+
+    Builder.suppressEnumCastWarning = true
+
+    val res = block // execute block
+
+    Builder.suppressEnumCastWarning = parentWarn
+    res
+  }
+}
diff --git a/core/src/main/scala/chisel3/internal/Builder.scala b/core/src/main/scala/chisel3/internal/Builder.scala
index 25f4c44c..b2c98309 100644
--- a/core/src/main/scala/chisel3/internal/Builder.scala
+++ b/core/src/main/scala/chisel3/internal/Builder.scala
@@ -435,6 +435,7 @@ private[chisel3] class DynamicContext(
   var currentReset:         Option[Reset] = None
   val errors = new ErrorLog
   val namingStack = new NamingStack
+
   // Used to indicate if this is the top-level module of full elaboration, or from a Definition
   var inDefinition: Boolean = false
 }
@@ -451,6 +452,9 @@ private[chisel3] object Builder extends LazyLogging {
     dynamicContextVar.value.get
   }
 
+  // Used to suppress warnings when casting from a UInt to an Enum
+  var suppressEnumCastWarning: Boolean = false
+
   // Returns the current dynamic context
   def captureContext(): DynamicContext = dynamicContext
   // Sets the current dynamic contents