From c214c1c82cbf0eb5685e1e31041b5f2dd063e548 Mon Sep 17 00:00:00 2001
From: Jonas Platte <jonas@lumeo.com>
Date: Fri, 2 Oct 2020 19:00:30 +0200
Subject: [PATCH] Update return type of Extensions::insert to match documented
 behavior

This is a breaking change, but Extensions::insert was strictly less
useful with the previous behavior.
---
 actix-http/CHANGES.md        | 3 +++
 actix-http/src/extensions.rs | 6 ++++--
 actix-http/src/helpers.rs    | 2 +-
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/actix-http/CHANGES.md b/actix-http/CHANGES.md
index 6a98c4ca7..facbaa470 100644
--- a/actix-http/CHANGES.md
+++ b/actix-http/CHANGES.md
@@ -2,6 +2,9 @@
 
 ## Unreleased - 2020-xx-xx
 
+### Changed
+
+* Change the return type of `Extensions::insert` from `()` to `Option<T>`
 
 ## 2.0.0 - 2020-09-11
 * No significant changes from `2.0.0-beta.4`.
diff --git a/actix-http/src/extensions.rs b/actix-http/src/extensions.rs
index 96e01767b..0e86b896e 100644
--- a/actix-http/src/extensions.rs
+++ b/actix-http/src/extensions.rs
@@ -24,8 +24,10 @@ impl Extensions {
     ///
     /// If a extension of this type already existed, it will
     /// be returned.
-    pub fn insert<T: 'static>(&mut self, val: T) {
-        self.map.insert(TypeId::of::<T>(), Box::new(val));
+    pub fn insert<T: 'static>(&mut self, val: T) -> Option<T> {
+        self.map
+            .insert(TypeId::of::<T>(), Box::new(val))
+            .and_then(|boxed| boxed.downcast().ok().map(|boxed| *boxed))
     }
 
     /// Check if container contains entry
diff --git a/actix-http/src/helpers.rs b/actix-http/src/helpers.rs
index bbf358b66..7ad272182 100644
--- a/actix-http/src/helpers.rs
+++ b/actix-http/src/helpers.rs
@@ -63,7 +63,7 @@ pub(crate) struct Data<T>(pub(crate) T);
 
 impl<T: Clone + 'static> DataFactory for Data<T> {
     fn set(&self, ext: &mut Extensions) {
-        ext.insert(self.0.clone())
+        ext.insert(self.0.clone());
     }
 }