Tweaks.

c++/src/capnp/dynamic.h

@@ -534,6 +534,8 @@ public:
   void setResults(DynamicStruct::Reader value);
   void adoptResults(Orphan<DynamicStruct>&& value);
   Orphanage getResultsOrphanage(uint firstSegmentWordSize = 0);
+  template <typename SubParams>
+  kj::Promise<void> tailCall(Request<SubParams, DynamicStruct>&& tailRequest);
   void allowAsyncCancellation();
   bool isCanceled();
 
@@ -1527,6 +1529,11 @@ inline Orphanage CallContext<DynamicStruct, DynamicStruct>::getResultsOrphanage(
     uint firstSegmentWordSize) {
   return Orphanage::getForMessageContaining(hook->getResults(firstSegmentWordSize));
 }
+template <typename SubParams>
+inline kj::Promise<void> CallContext<DynamicStruct, DynamicStruct>::tailCall(
+    Request<SubParams, DynamicStruct>&& tailRequest) {
+  return hook->tailCall(kj::mv(tailRequest.hook));
+}
 inline void CallContext<DynamicStruct, DynamicStruct>::allowAsyncCancellation() {
   hook->allowAsyncCancellation();
 }

c++/src/capnp/rpc-test.c++

@@ -100,7 +100,7 @@ public:
         return message->message.getRoot<ObjectPointer>();
       }
       void send() override {
-        //kj::String msg = kj::str(connection.name, ": ", message->message.getRoot<rpc::Message>());
+        kj::String msg = kj::str(connection.name, ": ", message->message.getRoot<rpc::Message>());
         //KJ_DBG(msg);
 
         KJ_IF_MAYBE(p, connection.partner) {

c++/src/capnp/rpc-twoparty-test.c++

@@ -45,6 +45,10 @@ public:
         return Capability::Client(newBrokenCap("No TestExtends implemented."));
       case test::TestSturdyRefObjectId::Tag::TEST_PIPELINE:
         return kj::heap<TestPipelineImpl>(callCount);
+      case test::TestSturdyRefObjectId::Tag::TEST_TAIL_CALLEE:
+        return kj::heap<TestTailCalleeImpl>(callCount);
+      case test::TestSturdyRefObjectId::Tag::TEST_TAIL_CALLER:
+        return kj::heap<TestTailCallerImpl>(callCount);
     }
     KJ_UNREACHABLE;
   }

c++/src/capnp/rpc.c++

@@ -2465,7 +2465,7 @@ private:
           break;
 
         default:
-          KJ_FAIL_REQUIRE("Unknown return type (not answer, exception, or canceled).") { return; }
+          KJ_FAIL_REQUIRE("Unknown 'Return' type.") { return; }
       }
 
       if (question->selfRef == nullptr) {