From d91c0f5ba3e22a08b70d371f9019874ae85dff06 Mon Sep 17 00:00:00 2001
From: David Pedersen <david.pdrsn@gmail.com>
Date: Fri, 3 Sep 2021 18:54:49 +0200
Subject: [PATCH] builder: Implement `Layer` for `ServiceBuilder` (#600)

---
 tower/CHANGELOG.md       |  2 +-
 tower/src/builder/mod.rs | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/tower/CHANGELOG.md b/tower/CHANGELOG.md
index 321955ea..0d8ee464 100644
--- a/tower/CHANGELOG.md
+++ b/tower/CHANGELOG.md
@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 # Unreleased
 
-Nothing yet.
+- **builder**: Implement `Layer` for `ServiceBuilder`.
 
 # 0.4.8 (May 28, 2021)
 
diff --git a/tower/src/builder/mod.rs b/tower/src/builder/mod.rs
index aed508cd..e7622f7f 100644
--- a/tower/src/builder/mod.rs
+++ b/tower/src/builder/mod.rs
@@ -673,3 +673,14 @@ impl<L: fmt::Debug> fmt::Debug for ServiceBuilder<L> {
         f.debug_tuple("ServiceBuilder").field(&self.layer).finish()
     }
 }
+
+impl<S, L> Layer<S> for ServiceBuilder<L>
+where
+    L: Layer<S>,
+{
+    type Service = L::Service;
+
+    fn layer(&self, inner: S) -> Self::Service {
+        self.layer.layer(inner)
+    }
+}