add stub set_pipeline methods

Author: dwrensha

capnp-rpc/src/local.rs

@@ -126,6 +126,10 @@ impl ResultsHook for Results {
         }
     }
 
+    fn set_pipeline(&mut self, pipeline: Box<dyn PipelineHook>) {
+        todo!()
+    }
+
     fn on_tail_call(&mut self) -> Promise<any_pointer::Pipeline, crate::Error> {
         todo!()
     }

capnp-rpc/src/rpc.rs

@@ -2295,6 +2295,10 @@ impl<VatId> ResultsHook for Results<VatId> {
         }
     }
 
+    fn set_pipeline(&mut self, pipeline: Box<dyn PipelineHook>) {
+        todo!()
+    }
+
     fn on_tail_call(&mut self) -> Promise<any_pointer::Pipeline, crate::Error> {
         todo!()
     }

capnp/src/capability.rs

@@ -223,7 +223,7 @@ pub struct Results<T> {
 
 impl<T> Results<T>
 where
-    T: Owned,
+    T: Owned + Pipelined,
 {
     pub fn new(hook: Box<dyn ResultsHook>) -> Self {
         Self {
@@ -240,9 +240,12 @@ where
         self.hook.get().unwrap().set_as(other)
     }
 
-    pub fn tail_call<SubParams>(self, tail_request: Request<SubParams, T>)
-                                -> Promise<(), Error>
-    {
+    pub fn set_pipeline(&mut self, pipeline: T::Pipeline) {
+        // How do we get a PipelineHook out of `pipeline`?
+        //self.hook.set_pipeline(pipeline)
+    }
+
+    pub fn tail_call<SubParams>(self, tail_request: Request<SubParams, T>) -> Promise<(), Error> {
         self.hook.tail_call(tail_request.hook)
     }
 }

capnp/src/private/capability.rs

@@ -95,9 +95,11 @@ pub trait ResultsHook {
     fn get(&mut self) -> crate::Result<any_pointer::Builder<'_>>;
     fn allow_cancellation(&self);
 
+    fn tail_call(self: Box<Self>, request: Box<dyn RequestHook>) -> Promise<(), crate::Error>;
+    fn set_pipeline(&mut self, pipeline: Box<dyn PipelineHook>);
+
     fn on_tail_call(&mut self) -> Promise<any_pointer::Pipeline, crate::Error>;
 
-    fn tail_call(self: Box<Self>, request: Box<dyn RequestHook>) -> Promise<(), crate::Error>;
     fn direct_tail_call(
         self: Box<Self>,
         request: Box<dyn RequestHook>,