3 files changed, 44 insertions, 17 deletions
diff --git a/core/src/main/scala/chisel3/StrongEnum.scala b/core/src/main/scala/chisel3/StrongEnum.scala
index 7d328eb7..1d0e04d3 100644
--- a/core/src/main/scala/chisel3/StrongEnum.scala
+++ b/core/src/main/scala/chisel3/StrongEnum.scala
@@ -131,7 +131,7 @@ abstract class EnumType(private val factory: EnumFactory, selfAnnotating: Boolea
     if (litOption.isDefined) {
       true.B
     } else {
-      factory.all.map(this === _).reduce(_ || _)
+      if (factory.isTotal) true.B else factory.all.map(this === _).reduce(_ || _)
     }
   }
 
@@ -233,6 +233,12 @@ abstract class EnumFactory {
 
   private[chisel3] val enumTypeName = getClass.getName.init
 
+  // Do all bitvectors of this Enum's width represent legal states?
+  private[chisel3] def isTotal: Boolean = {
+    (this.getWidth < 31) && // guard against Integer overflow
+      (enumRecords.size == (1 << this.getWidth))
+  }
+
   private[chisel3] def globalAnnotation: EnumDefChiselAnnotation =
     EnumDefChiselAnnotation(enumTypeName, (enumNames, enumValues).zipped.toMap)
 
@@ -277,7 +283,7 @@ abstract class EnumFactory {
 
   def apply(): Type = new Type
 
-  def apply(n: UInt)(implicit sourceInfo: SourceInfo, connectionCompileOptions: CompileOptions): Type = {
+  private def castImpl(n: UInt, warn: Boolean)(implicit sourceInfo: SourceInfo, connectionCompileOptions: CompileOptions): Type = {
     if (n.litOption.isDefined) {
       enumInstances.find(_.litValue == n.litValue) match {
         case Some(result) => result
@@ -288,8 +294,9 @@ 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 {
-      Builder.warning(s"Casting non-literal UInt to $enumTypeName. You can check that its value is legal by calling isValid")
-
+      if (warn && !this.isTotal) {
+        Builder.warning(s"Casting non-literal UInt to $enumTypeName. You can use $enumTypeName.safe to cast without this warning.")
+      }
       val glue = Wire(new UnsafeEnum(width))
       glue := n
       val result = Wire(new Type)
@@ -297,6 +304,25 @@ abstract class EnumFactory {
       result
     }
   }
+
+  /** Cast an [[UInt]] to the type of this Enum
+    *
+    * @note will give a Chisel elaboration time warning if the argument could hit invalid states
+    * @param n the UInt to cast
+    * @return the equivalent Enum to the value of the cast UInt
+    */
+  def apply(n: UInt)(implicit sourceInfo: SourceInfo, connectionCompileOptions: CompileOptions): Type = castImpl(n, warn = true)
+
+  /** Safely cast an [[UInt]] to the type of this Enum
+    *
+    * @param n the UInt to cast
+    * @return the equivalent Enum to the value of the cast UInt and a Bool indicating if the
+    *         Enum is valid
+    */
+  def safe(n: UInt)(implicit sourceInfo: SourceInfo, connectionCompileOptions: CompileOptions): (Type, Bool) = {
+    val t = castImpl(n, warn = false)
+    (t, t.isValid)
+  }
 }
 
 
diff --git a/core/src/main/scala/chisel3/internal/Builder.scala b/core/src/main/scala/chisel3/internal/Builder.scala
index 35c4bdf9..fef12093 100644
--- a/core/src/main/scala/chisel3/internal/Builder.scala
+++ b/core/src/main/scala/chisel3/internal/Builder.scala
@@ -652,7 +652,7 @@ private[chisel3] object Builder extends LazyLogging {
       logger.warn("Elaborating design...")
       val mod = f
       mod.forceName(None, mod.name, globalNamespace)
-      errors.checkpoint()
+      errors.checkpoint(logger)
       logger.warn("Done elaborating.")
 
       (Circuit(components.last.name, components.toSeq, annotations.toSeq), mod)
diff --git a/core/src/main/scala/chisel3/internal/Error.scala b/core/src/main/scala/chisel3/internal/Error.scala
index 454be360..d6e0c0e6 100644
--- a/core/src/main/scala/chisel3/internal/Error.scala
+++ b/core/src/main/scala/chisel3/internal/Error.scala
@@ -4,6 +4,7 @@ package chisel3.internal
 
 import scala.annotation.tailrec
 import scala.collection.mutable.{ArrayBuffer, LinkedHashMap}
+import _root_.logger.Logger
 
 object ExceptionHelpers {
 
@@ -184,31 +185,31 @@ private[chisel3] class ErrorLog {
   }
 
   /** Throw an exception if any errors have yet occurred. */
-  def checkpoint(): Unit = {
+  def checkpoint(logger: Logger): Unit = {
     deprecations.foreach { case ((message, sourceLoc), count) =>
-      println(s"${ErrorLog.depTag} $sourceLoc ($count calls): $message")
+      logger.warn(s"${ErrorLog.depTag} $sourceLoc ($count calls): $message")
     }
-    errors foreach println
+    errors.foreach(e => logger.error(e.toString))
 
     if (!deprecations.isEmpty) {
-      println(s"${ErrorLog.warnTag} ${Console.YELLOW}There were ${deprecations.size} deprecated function(s) used." +
+      logger.warn(s"${ErrorLog.warnTag} ${Console.YELLOW}There were ${deprecations.size} deprecated function(s) used." +
           s" These may stop compiling in a future release - you are encouraged to fix these issues.${Console.RESET}")
-      println(s"${ErrorLog.warnTag} Line numbers for deprecations reported by Chisel may be inaccurate; enable scalac compiler deprecation warnings via either of the following methods:")
-      println(s"${ErrorLog.warnTag}   In the sbt interactive console, enter:")
-      println(s"""${ErrorLog.warnTag}     set scalacOptions in ThisBuild ++= Seq("-unchecked", "-deprecation")""")
-      println(s"${ErrorLog.warnTag}   or, in your build.sbt, add the line:")
-      println(s"""${ErrorLog.warnTag}     scalacOptions := Seq("-unchecked", "-deprecation")""")
+      logger.warn(s"${ErrorLog.warnTag} Line numbers for deprecations reported by Chisel may be inaccurate; enable scalac compiler deprecation warnings via either of the following methods:")
+      logger.warn(s"${ErrorLog.warnTag}   In the sbt interactive console, enter:")
+      logger.warn(s"""${ErrorLog.warnTag}     set scalacOptions in ThisBuild ++= Seq("-unchecked", "-deprecation")""")
+      logger.warn(s"${ErrorLog.warnTag}   or, in your build.sbt, add the line:")
+      logger.warn(s"""${ErrorLog.warnTag}     scalacOptions := Seq("-unchecked", "-deprecation")""")
     }
 
     val allErrors = errors.filter(_.isFatal)
     val allWarnings = errors.filter(!_.isFatal)
 
     if (!allWarnings.isEmpty && !allErrors.isEmpty) {
-      println(s"${ErrorLog.errTag} There were ${Console.RED}${allErrors.size} error(s)${Console.RESET} and ${Console.YELLOW}${allWarnings.size} warning(s)${Console.RESET} during hardware elaboration.")
+      logger.warn(s"${ErrorLog.errTag} There were ${Console.RED}${allErrors.size} error(s)${Console.RESET} and ${Console.YELLOW}${allWarnings.size} warning(s)${Console.RESET} during hardware elaboration.")
     } else if (!allWarnings.isEmpty) {
-      println(s"${ErrorLog.warnTag} There were ${Console.YELLOW}${allWarnings.size} warning(s)${Console.RESET} during hardware elaboration.")
+      logger.warn(s"${ErrorLog.warnTag} There were ${Console.YELLOW}${allWarnings.size} warning(s)${Console.RESET} during hardware elaboration.")
     } else if (!allErrors.isEmpty) {
-      println(s"${ErrorLog.errTag} There were ${Console.RED}${allErrors.size} error(s)${Console.RESET} during hardware elaboration.")
+      logger.warn(s"${ErrorLog.errTag} There were ${Console.RED}${allErrors.size} error(s)${Console.RESET} during hardware elaboration.")
     }
 
     if (!allErrors.isEmpty) {