From a4388d32052c3bb64d643ebd6e46b5068f540340 Mon Sep 17 00:00:00 2001
From: Aditya Naik <aditya.naik@sifive.com>
Date: Wed, 27 May 2026 17:41:09 -0700
Subject: [PATCH 1/3] Move ConnectableSpec

---
 .../{scala-2 => scala}/chiselTests/ConnectableSpec.scala     | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
 rename src/test/{scala-2 => scala}/chiselTests/ConnectableSpec.scala (99%)

diff --git a/src/test/scala-2/chiselTests/ConnectableSpec.scala b/src/test/scala/chiselTests/ConnectableSpec.scala
similarity index 99%
rename from src/test/scala-2/chiselTests/ConnectableSpec.scala
rename to src/test/scala/chiselTests/ConnectableSpec.scala
index 71ca0168b08..39793c33eed 100644
--- a/src/test/scala-2/chiselTests/ConnectableSpec.scala
+++ b/src/test/scala/chiselTests/ConnectableSpec.scala
@@ -1847,8 +1847,9 @@ class ConnectableSpec extends AnyFunSpec with Matchers {
       val e = intercept[ChiselException] {
         ChiselStage.emitCHIRRTL(new MyModule, args = Array("--throw-on-first-error"))
       }
-      e.getMessage should include(
-        "mismatched widths of <unknown>.out: IO[UInt<4>] and <unknown>.in: IO[UInt<8>] might require truncation of <unknown>.in: IO[UInt<8>]"
+      // names show up as `null` in Scala 3 and `<unknown>` in Scala 2
+      e.getMessage should include regex(
+        "mismatched widths of .* and .* might require truncation of .*"
       )
     }
   }

From 8013608dc10463d5e0a6fbf8d0f7eaddec320a79 Mon Sep 17 00:00:00 2001
From: Aditya Naik <aditya.naik@sifive.com>
Date: Wed, 27 May 2026 17:47:06 -0700
Subject: [PATCH 2/3] Formatting

---
 src/test/scala/chiselTests/ConnectableSpec.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/scala/chiselTests/ConnectableSpec.scala b/src/test/scala/chiselTests/ConnectableSpec.scala
index 39793c33eed..cebc89caf2b 100644
--- a/src/test/scala/chiselTests/ConnectableSpec.scala
+++ b/src/test/scala/chiselTests/ConnectableSpec.scala
@@ -1848,7 +1848,7 @@ class ConnectableSpec extends AnyFunSpec with Matchers {
         ChiselStage.emitCHIRRTL(new MyModule, args = Array("--throw-on-first-error"))
       }
       // names show up as `null` in Scala 3 and `<unknown>` in Scala 2
-      e.getMessage should include regex(
+      (e.getMessage should include).regex(
         "mismatched widths of .* and .* might require truncation of .*"
       )
     }

From b65fe2aa981e86f97ea11673dea5f55bfee437f5 Mon Sep 17 00:00:00 2001
From: Aditya Naik <aditya.naik@sifive.com>
Date: Fri, 29 May 2026 17:47:13 -0700
Subject: [PATCH 3/3] Update propsed name to handle Scala 3 null values

Revert test changes
---
 core/src/main/scala/chisel3/Module.scala       | 18 +++++++++++++-----
 .../scala/chiselTests/ConnectableSpec.scala    |  5 ++---
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/core/src/main/scala/chisel3/Module.scala b/core/src/main/scala/chisel3/Module.scala
index cf09e5b2458..84b9c85db0a 100644
--- a/core/src/main/scala/chisel3/Module.scala
+++ b/core/src/main/scala/chisel3/Module.scala
@@ -714,11 +714,19 @@ package experimental {
       *
       * Includes the module prefix for user-defined modules (but not for blackboxes).
       */
-    private[chisel3] def _proposedName: String = this match {
-      // PseudoModules (e.g. Instances) and BlackBoxes have their names set by desiredName.
-      case _: PseudoModule => desiredName
-      case _: BaseBlackBox => desiredName
-      case _ => this.modulePrefix + desiredName
+    private[chisel3] def _proposedName: String = {
+      val dn = desiredName
+      // Handle Scala 3 null values
+      if (dn == null)
+        throw new NullPointerException(
+          s"desiredName of ${this.getClass.getName} is null"
+        )
+      this match {
+        // PseudoModules (e.g. Instances) and BlackBoxes have their names set by desiredName.
+        case _: PseudoModule => dn
+        case _: BaseBlackBox => dn
+        case _ => this.modulePrefix + dn
+      }
     }
 
     /** Legalized name of this module. */
diff --git a/src/test/scala/chiselTests/ConnectableSpec.scala b/src/test/scala/chiselTests/ConnectableSpec.scala
index cebc89caf2b..71ca0168b08 100644
--- a/src/test/scala/chiselTests/ConnectableSpec.scala
+++ b/src/test/scala/chiselTests/ConnectableSpec.scala
@@ -1847,9 +1847,8 @@ class ConnectableSpec extends AnyFunSpec with Matchers {
       val e = intercept[ChiselException] {
         ChiselStage.emitCHIRRTL(new MyModule, args = Array("--throw-on-first-error"))
       }
-      // names show up as `null` in Scala 3 and `<unknown>` in Scala 2
-      (e.getMessage should include).regex(
-        "mismatched widths of .* and .* might require truncation of .*"
+      e.getMessage should include(
+        "mismatched widths of <unknown>.out: IO[UInt<4>] and <unknown>.in: IO[UInt<8>] might require truncation of <unknown>.in: IO[UInt<8>]"
       )
     }
   }