From 7d338533912e972487201f1c77456fc07fd1c494 Mon Sep 17 00:00:00 2001
From: Jonas Platte <jplatte+git@posteo.de>
Date: Fri, 30 Sep 2022 11:13:46 +0200
Subject: [PATCH] Make blanket implementation of FromRef more general

---
 axum-core/src/extract/from_ref.rs | 9 ++++++---
 axum/src/routing/tests/merge.rs   | 2 +-
 axum/src/routing/tests/nest.rs    | 2 +-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/axum-core/src/extract/from_ref.rs b/axum-core/src/extract/from_ref.rs
index c0124140..7a674e75 100644
--- a/axum-core/src/extract/from_ref.rs
+++ b/axum-core/src/extract/from_ref.rs
@@ -1,3 +1,5 @@
+use std::borrow::Borrow;
+
 /// Used to do reference-to-value conversions thus not consuming the input value.
 ///
 /// This is mainly used with [`State`] to extract "substates" from a reference to main application
@@ -13,11 +15,12 @@ pub trait FromRef<T> {
     fn from_ref(input: &T) -> Self;
 }
 
-impl<T> FromRef<T> for T
+impl<T, U> FromRef<T> for U
 where
-    T: Clone,
+    T: Borrow<U>,
+    U: Clone,
 {
     fn from_ref(input: &T) -> Self {
-        input.clone()
+        input.borrow().clone()
     }
 }
diff --git a/axum/src/routing/tests/merge.rs b/axum/src/routing/tests/merge.rs
index 804549d3..41b4355e 100644
--- a/axum/src/routing/tests/merge.rs
+++ b/axum/src/routing/tests/merge.rs
@@ -469,7 +469,7 @@ async fn merging_routes_different_paths_different_states() {
 
 #[tokio::test]
 async fn inherit_state_via_merge() {
-    let foo = Router::inherit_state().route(
+    let foo = Router::<&'static str>::inherit_state().route(
         "/foo",
         get(|State(state): State<&'static str>| async move { state }),
     );
diff --git a/axum/src/routing/tests/nest.rs b/axum/src/routing/tests/nest.rs
index 42c4ffe9..dda151e1 100644
--- a/axum/src/routing/tests/nest.rs
+++ b/axum/src/routing/tests/nest.rs
@@ -473,7 +473,7 @@ async fn nesting_with_different_state() {
 
 #[tokio::test]
 async fn inherit_state_via_nest() {
-    let foo = Router::inherit_state().route(
+    let foo = Router::<&'static str>::inherit_state().route(
         "/foo",
         get(|State(state): State<&'static str>| async move { state }),
     );