[orchestra] fix: require the initialization with F: FnOnce to be Send

node/orchestra/examples/solo.rs

@@ -46,24 +46,29 @@ impl<Context> Fortified {
 	}
 }
 
-fn main() {
-	use futures::{executor, pin_mut};
+async fn setup() {
+	let builder = Solo::builder();
+
+	let builder = builder.goblin_tower(Fortified::default());
+
+	let builder = builder.spawner(DummySpawner);
+	let (orchestra, _handle): (Solo<_>, _) = builder.build().unwrap();
 
-	executor::block_on(async move {
-		let (orchestra, _handle): (Solo<_>, _) = Solo::builder()
-			.goblin_tower(Fortified::default())
-			.spawner(DummySpawner)
-			.build()
-			.unwrap();
+	let orchestra_fut = orchestra
+		.running_subsystems
+		.into_future()
+		.timeout(std::time::Duration::from_millis(300))
+		.fuse();
 
-		let orchestra_fut = orchestra
-			.running_subsystems
-			.into_future()
-			.timeout(std::time::Duration::from_millis(300))
-			.fuse();
+	futures::pin_mut!(orchestra_fut);
 
-		pin_mut!(orchestra_fut);
+	orchestra_fut.await;
+}
+
+fn assert_t_impl_trait_send<T: Send>(_: &T) {}
 
-		orchestra_fut.await
-	});
+fn main() {
+	let x = setup();
+	assert_t_impl_trait_send(&x);
+	futures::executor::block_on(x);
 }

node/orchestra/proc-macro/src/impl_builder.rs

@@ -172,7 +172,7 @@ pub(crate) fn impl_builder(info: &OrchestraInfo) -> proc_macro2::TokenStream {
 					pub fn #field_name_with<'a, F>(self, subsystem_init_fn: F ) ->
 						#builder <InitStateSpawner, #( #post_setter_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 					where
-						F: 'static + FnOnce(#handle) ->
+						F: 'static + Send + FnOnce(#handle) ->
 							::std::result::Result<#field_type, #error_ty>,
 					{
 						let boxed_func = Init::<#field_type>::Fn(
@@ -206,7 +206,7 @@ pub(crate) fn impl_builder(info: &OrchestraInfo) -> proc_macro2::TokenStream {
 						-> #builder <InitStateSpawner, #( #post_replace_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 					where
 						#field_type: 'static,
-						F: 'static + FnOnce(#field_type) -> NEW,
+						F: 'static + Send + FnOnce(#field_type) -> NEW,
 						NEW: #support_crate ::Subsystem<#subsystem_ctx_name< #subsystem_consumes >, #error_ty>,
 					{
 						let replacement: Init<NEW> = match self.#field_name {
@@ -333,7 +333,7 @@ pub(crate) fn impl_builder(info: &OrchestraInfo) -> proc_macro2::TokenStream {
 
 	let mut ts = quote! {
 		/// Convenience alias.
-		type SubsystemInitFn<T> = Box<dyn FnOnce(#handle) -> ::std::result::Result<T, #error_ty> >;
+		type SubsystemInitFn<T> = Box<dyn FnOnce(#handle) -> ::std::result::Result<T, #error_ty> + Send + 'static>;
 
 		/// Type for the initialized field of the orchestra builder
 		pub enum Init<T> {