src/main/wacc/renamer.scala

@@ -120,12 +120,15 @@ object renamer {
       globalNumbering: mutable.Map[String, Int],
       errors: mutable.Builder[Error, List[Error]]
   ): Unit = {
-    scope.current.withDefault(scope.parent).get((ident.v, identType)) match {
+    // Unfortunately map defaults only work with `.apply()`, which throws an error when the key is not found.
-      case Some(Ident(_, uid)) => ident.uid = uid
+    // Neither is there a way to check whether a default exists, so we have to use a try-catch.
-      case None => {
+    try {
+      val Ident(_, uid) = scope.current.withDefault(scope.parent)((ident.v, identType))
+      ident.uid = uid
+    } catch {
+      case _: NoSuchElementException =>
         errors += Error.UndefinedIdentifier(ident, identType)
         scope.add(?, ident, identType)
     }
   }
-  }
 }