[2.13] replace `= Unit` with `= ()`

2 files changed, 3 insertions, 3 deletions

diff --git a/src/main/scala/firrtl/options/OptionParser.scala b/src/main/scala/firrtl/options/OptionParser.scala
index 986c5a8a..9360a961 100644
--- a/src/main/scala/firrtl/options/OptionParser.scala
+++ b/src/main/scala/firrtl/options/OptionParser.scala
@@ -11,7 +11,7 @@ case object OptionsHelpException extends Exception("Usage help invoked")
 /** OptionParser mixin that causes the OptionParser to not call exit (call `sys.exit`) if the `--help` option is
   * passed */
 trait DoNotTerminateOnExit { this: OptionParser[_] =>
-  override def terminate(exitState: Either[String, Unit]): Unit = Unit
+  override def terminate(exitState: Either[String, Unit]): Unit = ()
 }
 
 /** OptionParser mixin that converts to [[OptionsException]]
@@ -28,7 +28,7 @@ trait ExceptOnError { this: OptionParser[_] =>
   */
 trait DuplicateHandling extends OptionParser[AnnotationSeq] {
 
-  override def parse(args: Seq[String], init: AnnotationSeq): Option[AnnotationSeq] = {
+  override def parse(args: scala.collection.Seq[String], init: AnnotationSeq): Option[AnnotationSeq] = {
 
     /** Message for found duplicate options */
     def msg(x: String, y: String) = s"""Duplicate $x "$y" (did your custom Transform or OptionsManager add this?)"""
diff --git a/src/main/scala/firrtl/options/Phase.scala b/src/main/scala/firrtl/options/Phase.scala
index 33e1dbb7..2a68251d 100644
--- a/src/main/scala/firrtl/options/Phase.scala
+++ b/src/main/scala/firrtl/options/Phase.scala
@@ -89,7 +89,7 @@ trait IdentityLike[A] { this: TransformLike[A] =>
     * @param a an input object
     * @return nothing
     */
-  protected def internalTransform(a: A): Unit = Unit
+  protected def internalTransform(a: A): Unit = ()
 
   /** This method will execute `internalTransform` and then return the original input object
     * @param a an input object