Fix missing generics on impl block (#26)

* fix missing generics on impl block

overwatch-derive/src/lib.rs

@@ -2,7 +2,7 @@ mod utils;
 
 use proc_macro_error::{abort_call_site, proc_macro_error};
 use quote::{format_ident, quote};
-use syn::{punctuated::Punctuated, token::Comma, Data, DeriveInput, Field};
+use syn::{punctuated::Punctuated, token::Comma, Data, DeriveInput, Field, Generics};
 
 #[proc_macro_derive(Services)]
 #[proc_macro_error]
@@ -29,11 +29,12 @@ fn impl_services(input: &DeriveInput) -> proc_macro2::TokenStream {
 
     let struct_identifier = &input.ident;
     let data = &input.data;
+    let generics = &input.generics;
     match data {
         Data::Struct(DataStruct {
             fields: syn::Fields::Named(fields),
             ..
-        }) => impl_services_for_struct(struct_identifier, &fields.named),
+        }) => impl_services_for_struct(struct_identifier, generics, &fields.named),
         _ => {
             abort_call_site!("Deriving Services is only supported for named Structs");
         }
@@ -42,11 +43,12 @@ fn impl_services(input: &DeriveInput) -> proc_macro2::TokenStream {
 
 fn impl_services_for_struct(
     identifier: &proc_macro2::Ident,
+    generics: &Generics,
     fields: &Punctuated<Field, Comma>,
 ) -> proc_macro2::TokenStream {
-    let settings = generate_services_settings(identifier, fields);
+    let settings = generate_services_settings(identifier, generics, fields);
-    let unique_ids_check = generate_assert_unique_identifiers(identifier, fields);
+    let unique_ids_check = generate_assert_unique_identifiers(identifier, generics, fields);
-    let services_impl = generate_services_impl(identifier, fields);
+    let services_impl = generate_services_impl(identifier, generics, fields);
 
     quote! {
         #unique_ids_check
@@ -59,6 +61,7 @@ fn impl_services_for_struct(
 
 fn generate_services_settings(
     services_identifier: &proc_macro2::Ident,
+    generics: &Generics,
     fields: &Punctuated<Field, Comma>,
 ) -> proc_macro2::TokenStream {
     let services_settings = fields.iter().map(|field| {
@@ -68,9 +71,10 @@ fn generate_services_settings(
         quote!(pub #service_name: <#_type as ::overwatch_rs::services::ServiceData>::Settings)
     });
     let services_settings_identifier = service_settings_identifier_from(services_identifier);
+    let where_clause = &generics.where_clause;
     quote! {
         #[derive(::std::clone::Clone, ::std::fmt::Debug)]
-        pub struct #services_settings_identifier {
+        pub struct #services_settings_identifier #generics #where_clause {
             #( #services_settings ),*
         }
     }
@@ -78,6 +82,7 @@ fn generate_services_settings(
 
 fn generate_assert_unique_identifiers(
     services_identifier: &proc_macro2::Ident,
+    generics: &Generics,
     fields: &Punctuated<Field, Comma>,
 ) -> proc_macro2::TokenStream {
     let services_ids = fields.iter().map(|field| {
@@ -90,14 +95,18 @@ fn generate_assert_unique_identifiers(
         "__{}__CONST_CHECK_UNIQUE_SERVICES_IDS",
         services_identifier.to_string().to_uppercase()
     );
+    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
 
     quote! {
+        impl #impl_generics #services_identifier #ty_generics #where_clause {
             const #services_ids_check: () = assert!(::overwatch_rs::utils::const_checks::unique_ids(&[#( #services_ids ),*]));
         }
     }
+}
 
 fn generate_services_impl(
     services_identifier: &proc_macro2::Ident,
+    generics: &Generics,
     fields: &Punctuated<Field, Comma>,
 ) -> proc_macro2::TokenStream {
     let services_settings_identifier = service_settings_identifier_from(services_identifier);
@@ -107,10 +116,11 @@ fn generate_services_impl(
     let impl_stop = generate_stop_impl(fields);
     let impl_relay = generate_request_relay_impl(fields);
     let impl_update_settings = generate_update_settings_impl(fields);
+    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
 
     quote! {
-        impl ::overwatch_rs::overwatch::Services for #services_identifier {
+        impl #impl_generics ::overwatch_rs::overwatch::Services for #services_identifier #ty_generics #where_clause {
-            type Settings = #services_settings_identifier;
+            type Settings = #services_settings_identifier #ty_generics;
 
             #impl_new
 

overwatch-rs/tests/generics.rs

@@ -0,0 +1,137 @@
+use async_trait::async_trait;
+use futures::future::select;
+use overwatch_derive::Services;
+use overwatch_rs::overwatch::OverwatchRunner;
+use overwatch_rs::services::handle::{ServiceHandle, ServiceStateHandle};
+use overwatch_rs::services::relay::RelayMessage;
+use overwatch_rs::services::state::{NoOperator, NoState};
+use overwatch_rs::services::{ServiceCore, ServiceData, ServiceId};
+use std::fmt::Debug;
+use std::time::Duration;
+use tokio::time::sleep;
+
+pub struct GenericService<T: Send>
+where
+    T: Debug + 'static + Sync,
+{
+    state: ServiceStateHandle<Self>,
+    _phantom: std::marker::PhantomData<T>,
+}
+
+#[derive(Clone, Debug)]
+pub struct GenericServiceMessage(String);
+
+impl RelayMessage for GenericServiceMessage {}
+
+impl<T: Send> ServiceData for GenericService<T>
+where
+    T: Debug + 'static + Sync,
+{
+    const SERVICE_ID: ServiceId = "FooService";
+    type Settings = ();
+    type State = NoState<Self::Settings>;
+    type StateOperator = NoOperator<Self::State>;
+    type Message = GenericServiceMessage;
+}
+
+#[async_trait]
+impl<T: Send> ServiceCore for GenericService<T>
+where
+    T: Debug + 'static + Sync,
+{
+    fn init(state: ServiceStateHandle<Self>) -> Result<Self, overwatch_rs::DynError> {
+        Ok(Self {
+            state,
+            _phantom: std::marker::PhantomData,
+        })
+    }
+
+    async fn run(mut self) -> Result<(), overwatch_rs::DynError> {
+        use tokio::io::{self, AsyncWriteExt};
+
+        let Self {
+            state: ServiceStateHandle {
+                mut inbound_relay, ..
+            },
+            ..
+        } = self;
+
+        let generic = async move {
+            let mut stdout = io::stdout();
+            while let Some(message) = inbound_relay.recv().await {
+                match message.0.as_ref() {
+                    "stop" => {
+                        stdout
+                            .write_all(b"genericing service stopping\n")
+                            .await
+                            .expect("stop Output wrote");
+                        break;
+                    }
+                    m => {
+                        stdout
+                            .write_all(format!("{m}\n").as_bytes())
+                            .await
+                            .expect("Message output wrote");
+                    }
+                }
+            }
+        };
+
+        let idle = async move {
+            let mut stdout = io::stdout();
+            loop {
+                stdout
+                    .write_all(b"Waiting for generic process to finish...\n")
+                    .await
+                    .expect("Message output wrote");
+                sleep(Duration::from_millis(50)).await;
+            }
+        };
+
+        select(Box::pin(generic), Box::pin(idle)).await;
+        Ok(())
+    }
+}
+
+#[derive(Services)]
+struct TestApp<T: Send>
+where
+    T: Debug + 'static + Sync,
+{
+    generic_service: ServiceHandle<GenericService<T>>,
+}
+
+#[test]
+fn derive_generic_service() {
+    let settings: TestAppServiceSettings<String> = TestAppServiceSettings {
+        generic_service: (),
+    };
+    let overwatch = OverwatchRunner::<TestApp<String>>::run(settings, None).unwrap();
+    let handle = overwatch.handle().clone();
+    let generic_service_relay = handle.relay::<GenericService<String>>();
+
+    overwatch.spawn(async move {
+        let generic_service_relay = generic_service_relay
+            .connect()
+            .await
+            .expect("A connection to the generic service is established");
+
+        for _ in 0..3 {
+            generic_service_relay
+                .send(GenericServiceMessage("Hey oh let's go!".to_string()))
+                .await
+                .expect("Message is sent");
+        }
+        sleep(Duration::from_millis(50)).await;
+        generic_service_relay
+            .send(GenericServiceMessage("stop".to_string()))
+            .await
+            .expect("stop message to be sent");
+    });
+
+    overwatch.spawn(async move {
+        sleep(Duration::from_secs(1)).await;
+        handle.shutdown().await;
+    });
+    overwatch.wait_finished();
+}