From d0237f1edd7bd3ef88133ea9e4238df8f4ea3bf1 Mon Sep 17 00:00:00 2001
From: Dmitry Olshansky <Olshanskydr@gmail.com>
Date: Wed, 14 Aug 2024 15:13:36 +0300
Subject: [PATCH] Add instance HasServer (EmptyAPI :> api) context (#1775)

* Add instance HasServer (EmptyAPI :> api) context

* add changelog
---
 changelog.d/1775                              | 2 ++
 servant-server/src/Servant/Server/Internal.hs | 9 ++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/1775

diff --git a/changelog.d/1775 b/changelog.d/1775
new file mode 100644
index 000000000..4bf712116
--- /dev/null
+++ b/changelog.d/1775
@@ -0,0 +1,2 @@
+synopsis: Add instance `HasServer (EmptyAPI :> api) context`
+prs: #1775
diff --git a/servant-server/src/Servant/Server/Internal.hs b/servant-server/src/Servant/Server/Internal.hs
index 965c626f2..a2818d18b 100644
--- a/servant-server/src/Servant/Server/Internal.hs
+++ b/servant-server/src/Servant/Server/Internal.hs
@@ -641,7 +641,7 @@ instance
 --
 -- The way the object is constructed from the extracted fields can be controlled by
 -- providing an instance on @'FromDeepQuery'@
--- 
+--
 -- Example:
 --
 -- > type MyApi = "books" :> DeepQuery "filter" BookQuery :> Get '[JSON] [Book]
@@ -914,6 +914,13 @@ instance HasServer EmptyAPI context where
 
   hoistServerWithContext _ _ _ = retag
 
+-- | Ignore @'EmptyAPI'@ as part of route in server handlers.
+instance HasServer api context => HasServer (EmptyAPI :> api) context where
+  type ServerT (EmptyAPI :> api) m = ServerT api m
+
+  route _ = route (Proxy :: Proxy api)
+  hoistServerWithContext _ = hoistServerWithContext (Proxy :: Proxy api)
+
 -- | Basic Authentication
 instance ( KnownSymbol realm
          , HasServer api context