Future<T>::then Future<T>::then() -> Future<T>::thenValue or thenTry.

Summary:
Part of the larger project to modify Future<T>::then to be r-value qualified and use Future<T>::thenTry or Future<T>::thenValue.

The goal is to disambiguate folly::Future and to improve type and lifetime safety of Future and its methods.

Codemod:
  future<T>.then(callable with operator()(not-a-try)) to future<T>.thenValue(callable with operator()(not-a-try)).
  future<T>.then(callable with operator()()) to future<T>.thenValue(callable with operator()(auto&&)).
  future<T>.then(callable with operator()(auto)) to future<T>.thenValue(callable with operator()(auto)).
  future<T>.then(callable with operator()(folly::Try<T>)) to future<T>.thenTry(callable)

Reviewed By: Orvid

Differential Revision: D9819433

fbshipit-source-id: f8a718f697edc4a175864cf741d18b0ab3e9ce83

Author: LeeHowes

rsocket/RSocket.cpp

@@ -56,7 +56,7 @@ folly::Future<std::unique_ptr<RSocketClient>> RSocket::createConnectedClient(
       };
 
   return connectionFactory->connect(protocolVersion, ResumeStatus::NEW_SESSION)
-      .then(
+      .thenValue(
           [createRSC = std::move(createRSC)](
               ConnectionFactory::ConnectedDuplexConnection connection) mutable {
             // fromConnection method must be called from the transport eventBase
@@ -96,8 +96,10 @@ folly::Future<std::unique_ptr<RSocketClient>> RSocket::createResumedClient(
       std::move(coldResumeHandler),
       stateMachineEvb);
 
-  return c->resume().then([client = std::unique_ptr<RSocketClient>(
-                               c)]() mutable { return std::move(client); });
+  return c->resume().thenValue(
+      [client = std::unique_ptr<RSocketClient>(c)](auto&&) mutable {
+        return std::move(client);
+      });
 }
 
 std::unique_ptr<RSocketClient> RSocket::createClientFromConnection(