[coroutines] Fix checking for prvalue-ness of `await_suspend` return type

Summary:
@rsmith Does this correctly address the issues mentioned in https://reviews.llvm.org/D33625#inline-292971 ?



Reviewers: rsmith, EricWF

Reviewed By: EricWF

Subscribers: cfe-commits, rsmith

Differential Revision: https://reviews.llvm.org/D33636

llvm-svn: 304373

1 files changed, 5 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaCoroutine.cpp b/clang/lib/Sema/SemaCoroutine.cpp
index f5594bd64d9..8a548c0ab86 100644
--- a/clang/lib/Sema/SemaCoroutine.cpp
+++ b/clang/lib/Sema/SemaCoroutine.cpp
@@ -391,8 +391,11 @@ static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
     // [expr.await]p3 [...]
     //   - await-suspend is the expression e.await_suspend(h), which shall be
     //     a prvalue of type void or bool.
-    QualType RetType = AwaitSuspend->getType();
-    if (RetType != S.Context.BoolTy && RetType != S.Context.VoidTy) {
+    QualType RetType = AwaitSuspend->getCallReturnType(S.Context);
+    // non-class prvalues always have cv-unqualified types
+    QualType AdjRetType = RetType.getUnqualifiedType();
+    if (RetType->isReferenceType() ||
+        (AdjRetType != S.Context.BoolTy && AdjRetType != S.Context.VoidTy)) {
       S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
              diag::err_await_suspend_invalid_return_type)
           << RetType;