From 2151711f64e99a5da370d48fa92795f2d4799866 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Dom=C3=ADnguez?= <adomu@net-c.com>
Date: Sat, 23 May 2020 15:27:38 +0200
Subject: [PATCH] Add NonAuthEndpoint trait

This is a way to mark any type implementing `Endpoint` as not
requiring authentication information through the type system.
This is useful for clients that build on top of the ruma crates
to check this condition at compile time, avoiding a runtime error.
---
 ruma-api-macros/src/api.rs | 10 ++++++++++
 src/lib.rs                 |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/ruma-api-macros/src/api.rs b/ruma-api-macros/src/api.rs
index 876b5ed5..e4a3a381 100644
--- a/ruma-api-macros/src/api.rs
+++ b/ruma-api-macros/src/api.rs
@@ -90,6 +90,14 @@ impl ToTokens for Api {
         let rate_limited = &self.metadata.rate_limited;
         let requires_authentication = &self.metadata.requires_authentication;
 
+        let non_auth_endpoint_impl = if requires_authentication.value {
+            quote! {
+                impl ruma_api::NonAuthEndpoint for Request {}
+            }
+        } else {
+            TokenStream::new()
+        };
+
         let request_type = &self.request;
         let response_type = &self.response;
 
@@ -507,6 +515,8 @@ impl ToTokens for Api {
                     requires_authentication: #requires_authentication,
                 };
             }
+
+            #non_auth_endpoint_impl
         };
 
         api.to_tokens(tokens);
diff --git a/src/lib.rs b/src/lib.rs
index 078f368c..4239732c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -236,6 +236,11 @@ pub trait Endpoint:
     const METADATA: Metadata;
 }
 
+/// A Matrix API endpoint that doesn't require authentication.
+///
+/// This marker trait is to indicate that a type implementing `Endpoint` doesn't require any authentication.
+pub trait NonAuthEndpoint: Endpoint {}
+
 /// Metadata about an API endpoint.
 #[derive(Clone, Debug)]
 pub struct Metadata {