From b785403f5f96404e1580ddcf3ce22e02d178248b Mon Sep 17 00:00:00 2001
From: Philippe-Cholet <44676486+Philippe-Cholet@users.noreply.github.com>
Date: Tue, 23 Jan 2024 11:48:23 +0100
Subject: [PATCH] `ExactlyOneError`: implement Debug differently

It could be derived. It apparently was decided not to in #484, probably to not leak implementation details that could confuse the user.
However, it would not render well for pretty formats such as `"{:#?}"`. I think we should call methods on `f` instead of using `write!`.
---
 src/exactly_one_err.rs | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/src/exactly_one_err.rs b/src/exactly_one_err.rs
index 90d898778..19b9e1918 100644
--- a/src/exactly_one_err.rs
+++ b/src/exactly_one_err.rs
@@ -102,25 +102,17 @@ where
     I::Item: Debug,
 {
     fn fmt(&self, f: &mut Formatter) -> FmtResult {
+        let mut dbg = f.debug_struct("ExactlyOneError");
         match &self.first_two {
             Some(Either::Left([first, second])) => {
-                write!(
-                    f,
-                    "ExactlyOneError[First: {:?}, Second: {:?}, RemainingIter: {:?}]",
-                    first, second, self.inner
-                )
+                dbg.field("first", first).field("second", second);
             }
             Some(Either::Right(second)) => {
-                write!(
-                    f,
-                    "ExactlyOneError[Second: {:?}, RemainingIter: {:?}]",
-                    second, self.inner
-                )
-            }
-            None => {
-                write!(f, "ExactlyOneError[RemainingIter: {:?}]", self.inner)
+                dbg.field("second", second);
             }
+            None => {}
         }
+        dbg.field("inner", &self.inner).finish()
     }
 }