From 018658b450b13f83c7b95a15932a718b77cc15d4 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Wed, 19 May 2021 18:32:16 +0200
Subject: [PATCH] Explain why we don't duplicate panics from other threads

---
 src/derived/slot.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/derived/slot.rs b/src/derived/slot.rs
index 7814a680..e0c608a6 100644
--- a/src/derived/slot.rs
+++ b/src/derived/slot.rs
@@ -354,7 +354,12 @@ where
                             },
                         });
 
-                        let result = future.wait().unwrap_or_else(|| Canceled::throw());
+                        let result = future.wait().unwrap_or_else(|| {
+                            // If the other thread panics, we treat this as cancelation: there is no
+                            // need to panic ourselves, since the original panic will already invoke
+                            // the panic hook and bubble up to the thread boundary (or be caught).
+                            Canceled::throw()
+                        });
                         ProbeState::UpToDate(if result.cycle.is_empty() {
                             Ok(result.value)
                         } else {