From 029254ab49dec829a14cedac56c385b57059733f Mon Sep 17 00:00:00 2001
From: Megan Wachs <megan@sifive.com>
Date: Wed, 10 Jul 2024 11:48:19 -0700
Subject: [PATCH] Add more information when probe types don't match (#4269)

---
 core/src/main/scala/chisel3/probe/package.scala | 10 ++++++++--
 src/test/scala/chiselTests/ProbeSpec.scala      |  4 ++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/core/src/main/scala/chisel3/probe/package.scala b/core/src/main/scala/chisel3/probe/package.scala
index fc097969623..1f23c886103 100644
--- a/core/src/main/scala/chisel3/probe/package.scala
+++ b/core/src/main/scala/chisel3/probe/package.scala
@@ -34,8 +34,14 @@ package object probe extends SourceInfoDoc {
     * @param probeExpr value to initialize the sink to
     */
   def define[T <: Data](sink: T, probeExpr: T)(implicit sourceInfo: SourceInfo): Unit = {
-    if (!sink.typeEquivalent(probeExpr, false /* we will check more more detailed probe info below */ )) {
-      Builder.error("Cannot define a probe on a non-equivalent type.")
+    val typeCheckResult = sink.findFirstTypeMismatch(
+      probeExpr,
+      strictTypes = true,
+      strictWidths = true,
+      strictProbeInfo = false /* we will check more more detailed probe info below */
+    )
+    typeCheckResult.foreach { msg =>
+      Builder.error(s"Cannot define a probe on a non-equivalent type.\n$msg")
     }
     requireHasProbeTypeModifier(sink, "Expected sink to be a probe.")
     requireNotChildOfProbe(sink, "Expected sink to be the root of a probe.")
diff --git a/src/test/scala/chiselTests/ProbeSpec.scala b/src/test/scala/chiselTests/ProbeSpec.scala
index d9aca214a82..fc8bd476632 100644
--- a/src/test/scala/chiselTests/ProbeSpec.scala
+++ b/src/test/scala/chiselTests/ProbeSpec.scala
@@ -382,6 +382,10 @@ class ProbeSpec extends ChiselFlatSpec with MatchesAndOmits with Utils {
       )
     }
     exc.getMessage should include("Cannot define a probe on a non-equivalent type.")
+    exc.getMessage should include(
+      "Left (ProbeSpec_Anon.p: IO[UInt<4>]) and Right (ProbeSpec_Anon.Node(ProbeSpec_Anon.w: Wire[Bool]): OpResult[Bool]) have different types"
+    )
+
   }
 
   "Probe of a probe type" should "fail" in {