serde: Remove the Outgoing trait

crates/ruma-client-api/src/session/login.rs

@@ -268,10 +268,6 @@ pub mod v3 {
         extra: JsonObject,
     }
 
-    impl Outgoing for CustomLoginInfo<'_> {
-        type Incoming = IncomingCustomLoginInfo;
-    }
-
     /// Client configuration provided by the server.
     #[derive(Clone, Debug, Deserialize, Serialize)]
     #[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]

crates/ruma-client-api/src/uiaa.rs

@@ -560,10 +560,6 @@ pub struct IncomingCustomAuthData {
     extra: JsonObject,
 }
 
-impl Outgoing for CustomAuthData<'_> {
-    type Incoming = IncomingCustomAuthData;
-}
-
 /// Identification information for the user.
 #[derive(Clone, Debug, PartialEq, Eq, Outgoing, Serialize)]
 #[serde(from = "user_serde::IncomingUserIdentifier", into = "user_serde::UserIdentifier<'_>")]

crates/ruma-common/src/serde.rs

@@ -72,22 +72,6 @@ where
     serde_json::from_str(val.get()).map_err(E::custom)
 }
 
-/// A type that can be sent to another party that understands the matrix protocol.
-///
-/// If any of the fields of `Self` don't implement serde's `Deserialize`, you can derive this trait
-/// to generate a corresponding 'Incoming' type that supports deserialization. This is useful for
-/// things like `ruma_common::events::EventResult`. For more details, see the
-/// [derive macro's documentation][doc].
-///
-/// [doc]: derive.Outgoing.html
-// TODO: Better explain how this trait relates to serde's traits
-pub trait Outgoing {
-    /// The 'Incoming' variant of `Self`.
-    type Incoming;
-}
-
-// -- Everything below is macro-related --
-
 pub use ruma_macros::{
     AsRefStr, DeserializeFromCowStr, DisplayAsRefStr, FromString, OrdAsRefStr, Outgoing,
     PartialEqAsRefStr, PartialOrdAsRefStr, SerializeAsRefStr, StringEnum, _FakeDeriveSerde,

crates/ruma-common/tests/api/manual_endpoint_impl.rs

@@ -12,7 +12,6 @@ use ruma_common::{
         AuthScheme, EndpointError, IncomingRequest, IncomingResponse, MatrixVersion, Metadata,
         OutgoingRequest, OutgoingResponse, SendAccessToken,
     },
-    serde::Outgoing,
     RoomAliasId, RoomId,
 };
 use serde::{Deserialize, Serialize};
@@ -24,10 +23,6 @@ pub struct Request {
     pub room_alias: Box<RoomAliasId>, // path
 }
 
-impl Outgoing for Request {
-    type Incoming = Self;
-}
-
 const METADATA: Metadata = Metadata {
     description: "Add an alias to a room.",
     method: Method::PUT,
@@ -116,10 +111,6 @@ struct RequestBody {
 #[derive(Clone, Copy, Debug)]
 pub struct Response;
 
-impl Outgoing for Response {
-    type Incoming = Self;
-}
-
 impl IncomingResponse for Response {
     type EndpointError = MatrixError;
 

crates/ruma-macros/src/serde/outgoing.rs

@@ -70,7 +70,7 @@ pub fn expand_derive_outgoing(input: DeriveInput) -> syn::Result<TokenStream> {
     };
 
     match data {
-        DataKind::Unit => Ok(impl_outgoing_with_incoming_self(&input, &ruma_common)),
+        DataKind::Unit => Ok(TokenStream::new()),
         DataKind::Enum(mut vars) => {
             let mut found_lifetime = false;
             for var in &mut vars {
@@ -81,30 +81,21 @@ pub fn expand_derive_outgoing(input: DeriveInput) -> syn::Result<TokenStream> {
                 }
             }
 
-            let original_ident = &input.ident;
-            let (original_impl_gen, original_ty_gen, _) = input.generics.split_for_impl();
-
             if !found_lifetime {
-                return Ok(impl_outgoing_with_incoming_self(&input, &ruma_common));
+                return Ok(TokenStream::new());
             }
 
             let vis = input.vis;
             let doc = format!("'Incoming' variant of [{ty}](enum.{ty}.html).", ty = &input.ident);
-            let incoming_ident =
+            let incoming_ident = format_ident!("Incoming{}", input.ident, span = Span::call_site());
-                format_ident!("Incoming{}", original_ident, span = Span::call_site());
             let mut gen_copy = input.generics.clone();
-            let (impl_gen, ty_gen) = split_for_impl_lifetime_less(&mut gen_copy);
+            let (_, ty_gen) = split_for_impl_lifetime_less(&mut gen_copy);
 
             Ok(quote! {
                 #[doc = #doc]
                 #[derive( #( #derives ),* )]
                 #( #input_attrs )*
                 #vis enum #incoming_ident #ty_gen { #( #vars, )* }
-
-                #[automatically_derived]
-                impl #original_impl_gen #ruma_common::serde::Outgoing for #original_ident #original_ty_gen {
-                    type Incoming = #incoming_ident #impl_gen;
-                }
             })
         }
         DataKind::Struct(mut fields, struct_kind) => {
@@ -118,19 +109,15 @@ pub fn expand_derive_outgoing(input: DeriveInput) -> syn::Result<TokenStream> {
                 }
             }
 
-            let original_ident = &input.ident;
-            let (original_impl_gen, original_ty_gen, _) = input.generics.split_for_impl();
-
             if !found_lifetime {
-                return Ok(impl_outgoing_with_incoming_self(&input, &ruma_common));
+                return Ok(TokenStream::new());
             }
 
             let vis = input.vis;
             let doc = format!("'Incoming' variant of [{ty}](struct.{ty}.html).", ty = &input.ident);
-            let incoming_ident =
+            let incoming_ident = format_ident!("Incoming{}", input.ident, span = Span::call_site());
-                format_ident!("Incoming{}", original_ident, span = Span::call_site());
             let mut gen_copy = input.generics.clone();
-            let (impl_gen, ty_gen) = split_for_impl_lifetime_less(&mut gen_copy);
+            let (_, ty_gen) = split_for_impl_lifetime_less(&mut gen_copy);
 
             let struct_def = match struct_kind {
                 StructKind::Struct => quote! { { #(#fields,)* } },
@@ -142,11 +129,6 @@ pub fn expand_derive_outgoing(input: DeriveInput) -> syn::Result<TokenStream> {
                 #[derive( #( #derives ),* )]
                 #( #input_attrs )*
                 #vis struct #incoming_ident #ty_gen #struct_def
-
-                #[automatically_derived]
-                impl #original_impl_gen #ruma_common::serde::Outgoing for #original_ident #original_ty_gen {
-                    type Incoming = #incoming_ident #impl_gen;
-                }
             })
         }
     }
@@ -162,18 +144,6 @@ fn filter_input_attrs(attr: &Attribute) -> bool {
         || attr.path.is_ident("allow")
 }
 
-fn impl_outgoing_with_incoming_self(input: &DeriveInput, ruma_common: &TokenStream) -> TokenStream {
-    let ident = &input.ident;
-    let (impl_gen, ty_gen, _) = input.generics.split_for_impl();
-
-    quote! {
-        #[automatically_derived]
-        impl #impl_gen #ruma_common::serde::Outgoing for #ident #ty_gen {
-            type Incoming = Self;
-        }
-    }
-}
-
 fn split_for_impl_lifetime_less(generics: &mut Generics) -> (ImplGenerics<'_>, TypeGenerics<'_>) {
     generics.params = generics
         .params