Remove std::move after co_return for local variables

Summary:
Compiler passes rvalue reference for named local variable to return_value:
https://reviews.llvm.org/D51741

Reviewed By: lewissbaker

Differential Revision: D16963353

fbshipit-source-id: 98d846153adb2235b61bb8fb54d10f032d4c0055

folly/experimental/coro/Collect-inl.h

@@ -170,7 +170,7 @@ auto collectAllRange(InputRange awaitables)
     values.push_back(std::move(result).value());
   }
 
-  co_return std::move(values);
+  co_return values;
 }
 
 template <
@@ -294,7 +294,7 @@ auto collectAllTryRange(InputRange awaitables)
     co_await detail::UnsafeResumeInlineSemiAwaitable{barrier.arriveAndWait()};
   }
 
-  co_return std::move(results);
+  co_return results;
 }
 
 template <
@@ -413,7 +413,7 @@ auto collectAllWindowed(InputRange awaitables, std::size_t maxConcurrency)
     results.emplace_back(std::move(tryResult).value());
   }
 
-  co_return std::move(results);
+  co_return results;
 }
 
 template <typename InputRange>
@@ -548,7 +548,7 @@ auto collectAllTryWindowed(InputRange awaitables, std::size_t maxConcurrency)
     std::rethrow_exception(std::move(workerCreationException));
   }
 
-  co_return std::move(results);
+  co_return results;
 }
 
 } // namespace coro

folly/experimental/coro/test/InlineTaskTest.cpp

@@ -183,10 +183,7 @@ TEST(InlineTask, TaskOfMoveOnlyType) {
 TEST(InlineTask, MoveOnlyTypeNRVO) {
   auto f = []() -> InlineTask<MoveOnlyType> {
     MoveOnlyType x{10};
-
-    // Shouldn't need std::move(x) here, according to
-    // N4760 15.8.3(3) Copy/move elision
-    co_return std::move(x);
+    co_return x;
   };
 
   auto x = folly::coro::blockingWait(f());