From 5e64fc4ff668179642a17f919b314b392cd2c93a Mon Sep 17 00:00:00 2001
From: Geoffry Song <goffrie@dropbox.com>
Date: Wed, 29 Apr 2020 23:56:53 -0700
Subject: [PATCH 1/2] Implement `Error::source` for `h2::Error`.

This makes it easier to detect an IO error at the bottom of an error
cause chain (e.g. behind a `hyper::Error`).

Also, don't implement `std::error::Error` for the private error types,
to avoid confusion.
---
 src/codec/error.rs | 8 +-------
 src/error.rs       | 9 ++++++++-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/codec/error.rs b/src/codec/error.rs
index 2c6b2961d..87ab82bf9 100644
--- a/src/codec/error.rs
+++ b/src/codec/error.rs
@@ -1,6 +1,6 @@
 use crate::frame::{Reason, StreamId};
 
-use std::{error, fmt, io};
+use std::{fmt, io};
 
 /// Errors that are received
 #[derive(Debug)]
@@ -73,8 +73,6 @@ impl From<io::Error> for RecvError {
     }
 }
 
-impl error::Error for RecvError {}
-
 impl fmt::Display for RecvError {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         use self::RecvError::*;
@@ -89,8 +87,6 @@ impl fmt::Display for RecvError {
 
 // ===== impl SendError =====
 
-impl error::Error for SendError {}
-
 impl fmt::Display for SendError {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         use self::SendError::*;
@@ -117,8 +113,6 @@ impl From<UserError> for SendError {
 
 // ===== impl UserError =====
 
-impl error::Error for UserError {}
-
 impl fmt::Display for UserError {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         use self::UserError::*;
diff --git a/src/error.rs b/src/error.rs
index 372bac2ee..71f119057 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -132,4 +132,11 @@ impl fmt::Display for Error {
     }
 }
 
-impl error::Error for Error {}
+impl error::Error for Error {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        match self.kind {
+            Kind::Io(ref e) => Some(e),
+            _ => None,
+        }
+    }
+}

From e4d3b6167a3cd352c9e98397b5400c435af87005 Mon Sep 17 00:00:00 2001
From: Geoffry Song <goffrie@gmail.com>
Date: Mon, 29 Apr 2024 10:16:56 -0700
Subject: [PATCH 2/2] fmt

---
 src/error.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/error.rs b/src/error.rs
index 02d91cbec..69831f3c5 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -223,7 +223,9 @@ mod tests {
     fn io_error_source() {
         let err = Error::from_io(io::Error::new(io::ErrorKind::BrokenPipe, "hi"));
         let source = err.source().expect("io error should have source");
-        let io_err = source.downcast_ref::<io::Error>().expect("should be io error");
+        let io_err = source
+            .downcast_ref::<io::Error>()
+            .expect("should be io error");
         assert_eq!(io_err.kind(), io::ErrorKind::BrokenPipe);
     }
 }