Index: lib/Sema/SemaCoroutine.cpp
===================================================================
--- lib/Sema/SemaCoroutine.cpp
+++ lib/Sema/SemaCoroutine.cpp
@@ -437,6 +437,7 @@
   if (VD->isInvalidDecl())
     return nullptr;
   ActOnUninitializedDecl(VD);
+  FD->addDecl(VD);
   assert(!VD->isInvalidDecl());
   return VD;
 }
Index: test/SemaCXX/coreturn.cpp
===================================================================
--- test/SemaCXX/coreturn.cpp
+++ test/SemaCXX/coreturn.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin9 %s -std=c++14 -fcoroutines-ts -fsyntax-only -Wignored-qualifiers -Wno-error=return-type -verify -fblocks -Wno-unreachable-code -Wno-unused-value
+// RUN: %clang_cc1 -triple x86_64-apple-darwin9 %s -std=c++14 -fcoroutines-ts -fsyntax-only -Wignored-qualifiers -Wno-error=return-type -verify -fblocks -Wall -Wextra -Wno-error=unreachable-code
 #include "Inputs/std-coroutine.h"
 
 using std::experimental::suspend_always;
Index: test/SemaCXX/coroutine-uninitialized-warning-crash.cpp
===================================================================
--- /dev/null
+++ test/SemaCXX/coroutine-uninitialized-warning-crash.cpp
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin9 %s -std=c++14 -fcoroutines-ts -fsyntax-only -Wall -Wextra -Wuninitialized  -fblocks
+#include "Inputs/std-coroutine.h"
+
+using namespace std::experimental;
+
+
+struct A {
+  bool await_ready() { return true; }
+  int await_resume() { return 42; }
+  template <typename F>
+  void await_suspend(F) {}
+};
+
+
+struct coro_t {
+  struct promise_type {
+    coro_t get_return_object() { return {}; }
+    suspend_never initial_suspend() { return {}; }
+    suspend_never final_suspend() { return {}; }
+    A yield_value(int) { return {}; }
+    void return_void() {}
+    static void unhandled_exception() {}
+  };
+};
+
+coro_t f(int n) {
+  if (n == 0)
+    co_return;
+  co_yield 42;
+  int x = co_await A{};
+}
+
+template <class Await>
+coro_t g(int n) {
+  if (n == 0)
+    co_return;
+  co_yield 42;
+  int x = co_await Await{};
+}
+
+int main() {
+  f(0);
+  g<A>(0);
+}