From 5c0bc080ea9175be54b4d1154081418727df0404 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=CE=A3rebe=20-=20Romain=20GERARD?= <erebe@erebe.eu>
Date: Sat, 14 Jan 2023 19:00:58 +0100
Subject: [PATCH] fix panic when Unfold sink return an error

  - fix issue #2600. When an Unfold sink return an error
  it is left in an invalid state. Calling after that flush/close
  cause the sink to panic due to re-calling a future already completed.

  This patch aims to leave the sink in a valid state and allow calling
  flush/close without causing a panic.
---
 futures-util/src/sink/unfold.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/futures-util/src/sink/unfold.rs b/futures-util/src/sink/unfold.rs
index b5adf60ee0..165f80f1a0 100644
--- a/futures-util/src/sink/unfold.rs
+++ b/futures-util/src/sink/unfold.rs
@@ -73,7 +73,10 @@ where
                     this.state.set(UnfoldState::Value { value: state });
                     Ok(())
                 }
-                Err(err) => Err(err),
+                Err(err) => {
+                    this.state.set(UnfoldState::Empty);
+                    Err(err)
+                }
             }
         } else {
             Ok(())