Support non-copyable types in folly::coro::timed_wait

Summary: If timed_wait is called with an awaitable that has a non-copyable return value then we must std::move the result.

Reviewed By: iahs

Differential Revision: D25222893

fbshipit-source-id: bd3c0ca19d182a464ad4b430f1792dcfff54ffdf

folly/experimental/coro/TimedWait.h

@@ -65,9 +65,7 @@ timed_wait(Awaitable awaitable, Duration duration) {
   if (!result.hasValue() && !result.hasException()) {
     co_return folly::none;
   }
-  // clang-format off
-  co_return *result;
-  // clang-format on
+  co_return std::move(*result);
 }
 
 } // namespace coro

folly/experimental/coro/test/CoroTest.cpp

@@ -354,6 +354,19 @@ TEST_F(CoroTest, TimedWaitKeepAlive) {
   EXPECT_LE(duration, std::chrono::seconds{30});
 }
 
+TEST_F(CoroTest, TimedWaitNonCopyable) {
+  auto task = []() -> coro::Task<std::unique_ptr<int>> {
+    co_return std::make_unique<int>(42);
+  }();
+  EXPECT_EQ(
+      42,
+      **coro::blockingWait(
+          [&]() -> coro::Task<folly::Optional<std::unique_ptr<int>>> {
+            co_return co_await coro::timed_wait(
+                std::move(task), std::chrono::seconds{60});
+          }()));
+}
+
 template <int value>
 struct AwaitableInt {
   bool await_ready() const { return true; }