Index: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8720,10 +8720,6 @@
   "|a copy assignment operator|a move assignment operator|the 'main' function"
   "|a constexpr function|a function with a deduced return type"
   "|a varargs function}0">;
-def ext_coroutine_without_co_await_co_yield : ExtWarn<
-  "'co_return' used in a function "
-  "that uses neither 'co_await' nor 'co_yield'">,
-  InGroup<DiagGroup<"coreturn-without-coawait">>;
 def err_implied_std_coroutine_traits_not_found : Error<
   "you need to include <experimental/coroutine> before defining a coroutine">;
 def err_malformed_std_coroutine_traits : Error<
Index: cfe/trunk/lib/Sema/SemaCoroutine.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaCoroutine.cpp
+++ cfe/trunk/lib/Sema/SemaCoroutine.cpp
@@ -578,17 +578,6 @@
             isa<CoyieldExpr>(First) ? 1 : 2);
   }
 
-  bool AnyCoawaits = false;
-  bool AnyCoyields = false;
-  for (auto *CoroutineStmt : Fn->CoroutineStmts) {
-    AnyCoawaits |= isa<CoawaitExpr>(CoroutineStmt);
-    AnyCoyields |= isa<CoyieldExpr>(CoroutineStmt);
-  }
-
-  if (!AnyCoawaits && !AnyCoyields)
-    Diag(Fn->CoroutineStmts.front()->getLocStart(),
-         diag::ext_coroutine_without_co_await_co_yield);
-
   SourceLocation Loc = FD->getLocation();
 
   // Form a declaration statement for the promise declaration, so that AST
Index: cfe/trunk/test/SemaCXX/coroutines.cpp
===================================================================
--- cfe/trunk/test/SemaCXX/coroutines.cpp
+++ cfe/trunk/test/SemaCXX/coroutines.cpp
@@ -154,12 +154,11 @@
 }
 
 void only_coreturn(void_tag) {
-  co_return; // expected-warning {{'co_return' used in a function that uses neither 'co_await' nor 'co_yield'}}
+  co_return; // OK
 }
 
 void mixed_coreturn(void_tag, bool b) {
   if (b)
-    // expected-warning@+1 {{'co_return' used in a function that uses neither}}
     co_return; // expected-note {{use of 'co_return'}}
   else
     return; // expected-error {{not allowed in coroutine}}