Successfully build some tests with GCC

Summary: Patch code to address build failures discovered with GCC.

Reviewed By: ericniebler

Differential Revision: D26682213

fbshipit-source-id: a45751e00ddbce01623e266bf3d6c9a72df40d26

folly/experimental/coro/Collect-inl.h

@@ -238,14 +238,14 @@ auto makeUnorderedAsyncGeneratorFromAwaitableRangeImpl(
       scopeParam.add(
           [](auto semiAwaitableParam,
              auto& cancelSourceParam,
-             auto& pipe) -> Task<void> {
+             auto& p) -> Task<void> {
             auto result = co_await co_withCancellation(
                 cancelSourceParam.getToken(),
                 co_awaitTry(std::move(semiAwaitableParam)));
             if (!result.hasValue() && !IsTry::value) {
               cancelSourceParam.requestCancellation();
             }
-            pipe.write(std::move(result));
+            p.write(std::move(result));
           }(static_cast<decltype(semiAwaitable)&&>(semiAwaitable),
             cancelSource,
             pipe)

folly/experimental/coro/CurrentExecutor.h

@@ -70,6 +70,7 @@ class co_reschedule_on_current_executor_ {
     folly::Executor::KeepAlive<> executor_;
   };
 
+ public:
   class StackAwareAwaiter : public AwaiterBase {
    public:
     using AwaiterBase::AwaiterBase;

folly/experimental/coro/ViaIfAsync.h

@@ -298,8 +298,8 @@ class ViaIfAsyncAwaiter {
   // case.
 
   template <typename Promise>
-  auto await_suspend(coroutine_handle<Promise> continuation) noexcept(
-      noexcept(awaiter_.await_suspend(std::declval<WrapperHandle>())))
+  auto await_suspend(coroutine_handle<Promise> continuation) noexcept(noexcept(
+      std::declval<Awaiter&>().await_suspend(std::declval<WrapperHandle>())))
       -> await_suspend_result_t {
     viaCoroutine_.setContinuation(continuation);
 

folly/experimental/coro/test/CoroTest.cpp

@@ -33,6 +33,7 @@
 #include <folly/fibers/Semaphore.h>
 #include <folly/futures/Future.h>
 #include <folly/io/async/ScopedEventBaseThread.h>
+#include <folly/lang/Assume.h>
 #include <folly/portability/GTest.h>
 
 #if FOLLY_HAS_COROUTINES
@@ -362,9 +363,7 @@ template <int value>
 struct AwaitableInt {
   bool await_ready() const { return true; }
 
-  bool await_suspend(coro::coroutine_handle<>) {
-    LOG(FATAL) << "Should never be called.";
-  }
+  bool await_suspend(coro::coroutine_handle<>) { assume_unreachable(); }
 
   int await_resume() { return value; }
 };
@@ -556,7 +555,7 @@ TEST_F(CoroTest, CancelOutstandingSemaphoreWait) {
             // whcih should reqeust cancellation of sem.co_wait().
             co_yield folly::coro::co_error(ExpectedError{});
           }());
-    } catch (ExpectedError) {
+    } catch (const ExpectedError&) {
     }
   }());
 }