Workaround for opt-gcc compiler bug

Summary: This diff appears to work around a compiler bug in gcc10 with coroutines. GCC is not keeping alive a temporary passed to a coroutine function.

Reviewed By: nmagerko

Differential Revision: D29847926

fbshipit-source-id: 69e0fc4cece8f5d0e26647581800ad81b1e44c74

folly/experimental/channels/Transform-inl.h

@@ -357,11 +357,12 @@ class ResumableTransformProcessor : public TransformProcessorBase<
     auto initializeResult =
         co_await folly::coro::co_awaitTry(initializeTransform_());
     if (initializeResult.hasException()) {
-      co_await processReceiverCancelled(
+      auto closeResult =
           initializeResult.template hasException<OnClosedException>()
           ? CloseResult()
-              : CloseResult(std::move(initializeResult.exception())),
-          true /* noRetriesAllowed */);
+          : CloseResult(std::move(initializeResult.exception()));
+      co_await processReceiverCancelled(
+          std::move(closeResult), true /* noRetriesAllowed */);
       co_return;
     }
     auto [initialValues, inputReceiver] = std::move(initializeResult.value());