From 588086db8c1844aed41d91787b3509c72cba76d6 Mon Sep 17 00:00:00 2001
From: Nathaniel McCallum <nathaniel@profian.com>
Date: Fri, 1 Apr 2022 17:25:50 -0400
Subject: [PATCH] feat: add response::Error

This type makes for efficient use of the `?` operator when in a function
with multiple return error types that all implement `IntoResponse`.

Signed-off-by: Nathaniel McCallum <nathaniel@profian.com>
---
 axum-core/src/response/error.rs | 26 ++++++++++++++++++++++++++
 axum-core/src/response/mod.rs   |  3 +++
 2 files changed, 29 insertions(+)
 create mode 100644 axum-core/src/response/error.rs

diff --git a/axum-core/src/response/error.rs b/axum-core/src/response/error.rs
new file mode 100644
index 00000000000..50257a8d7e2
--- /dev/null
+++ b/axum-core/src/response/error.rs
@@ -0,0 +1,26 @@
+use super::{IntoResponse, Response};
+
+/// An [IntoResponse]-based error type
+///
+/// All types which implement [IntoResponse] can be converted to an [Error].
+/// This makes it useful as a general error type for functions which combine
+/// multiple distinct error types but all of which implement [IntoResponse].
+#[derive(Debug)]
+pub struct Error(Response);
+
+impl<T: IntoResponse> From<T> for Error {
+    #[inline]
+    fn from(value: T) -> Self {
+        Self(value.into_response())
+    }
+}
+
+impl<T: IntoResponse> IntoResponse for Result<T, Error> {
+    #[inline]
+    fn into_response(self) -> Response {
+        match self {
+            Ok(ok) => ok.into_response(),
+            Err(err) => err.0,
+        }
+    }
+}
diff --git a/axum-core/src/response/mod.rs b/axum-core/src/response/mod.rs
index 687743fe825..d41485eac0d 100644
--- a/axum-core/src/response/mod.rs
+++ b/axum-core/src/response/mod.rs
@@ -9,7 +9,10 @@ use crate::body::BoxBody;
 mod into_response;
 mod into_response_parts;
 
+mod error;
+
 pub use self::{
+    error::Error,
     into_response::IntoResponse,
     into_response_parts::{IntoResponseParts, ResponseParts, TryIntoHeaderError},
 };