From: Eric Fiselier <eric@efcs.ca>
Date: Wed, 31 May 2017 23:41:11 +0000 (+0000)
Subject: [coroutines] Fix checking for prvalue-ness of `await_suspend` return type
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1cf6697b4406b7febeb4f9fdaa49ff494923505b;p=clang

[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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@304373 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 629e8b837f..4de4f47b8a 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8979,10 +8979,10 @@ def err_coroutine_promise_new_requires_nothrow : Error<
 def note_coroutine_promise_call_implicitly_required : Note<
   "call to %0 implicitly required by coroutine function here">;
 def err_await_suspend_invalid_return_type : Error<
-  "the return type of 'await_suspend' is required to be 'void' or 'bool' (have %0)"
+  "return type of 'await_suspend' is required to be 'void' or 'bool' (have %0)"
 >;
 def note_await_ready_no_bool_conversion : Note<
-  "the return type of 'await_ready' is required to be contextually convertible to 'bool'"
+  "return type of 'await_ready' is required to be contextually convertible to 'bool'"
 >;
 }
 
diff --git a/lib/Sema/SemaCoroutine.cpp b/lib/Sema/SemaCoroutine.cpp
index f5594bd64d..8a548c0ab8 100644
--- a/lib/Sema/SemaCoroutine.cpp
+++ b/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;
diff --git a/test/SemaCXX/coroutines.cpp b/test/SemaCXX/coroutines.cpp
index 47ad86e5b0..a867cf68a6 100644
--- a/test/SemaCXX/coroutines.cpp
+++ b/test/SemaCXX/coroutines.cpp
@@ -840,12 +840,12 @@ coro<bad_promise_no_return_func> no_return_value_or_return_void() {
 
 struct bad_await_suspend_return {
   bool await_ready();
-  // expected-error@+1 {{the return type of 'await_suspend' is required to be 'void' or 'bool' (have 'char')}}
+  // expected-error@+1 {{return type of 'await_suspend' is required to be 'void' or 'bool' (have 'char')}}
   char await_suspend(std::experimental::coroutine_handle<>);
   void await_resume();
 };
 struct bad_await_ready_return {
-  // expected-note@+1 {{the return type of 'await_ready' is required to be contextually convertible to 'bool'}}
+  // expected-note@+1 {{return type of 'await_ready' is required to be contextually convertible to 'bool'}}
   void await_ready();
   bool await_suspend(std::experimental::coroutine_handle<>);
   void await_resume();
@@ -858,6 +858,14 @@ struct await_ready_explicit_bool {
   void await_suspend(std::experimental::coroutine_handle<>);
   void await_resume();
 };
+template <class SuspendTy>
+struct await_suspend_type_test {
+  bool await_ready();
+  // expected-error@+2 {{return type of 'await_suspend' is required to be 'void' or 'bool' (have 'bool &')}}
+  // expected-error@+1 {{return type of 'await_suspend' is required to be 'void' or 'bool' (have 'bool &&')}}
+  SuspendTy await_suspend(std::experimental::coroutine_handle<>);
+  void await_resume();
+};
 void test_bad_suspend() {
   {
     // FIXME: The actual error emitted here is terrible, and no number of notes can save it.
@@ -873,4 +881,14 @@ void test_bad_suspend() {
     await_ready_explicit_bool c;
     co_await c; // OK
   }
+  {
+    await_suspend_type_test<bool &&> a;
+    await_suspend_type_test<bool &> b;
+    await_suspend_type_test<const void> c;
+    await_suspend_type_test<const volatile bool> d;
+    co_await a; // expected-note {{call to 'await_suspend' implicitly required by coroutine function here}}
+    co_await b; // expected-note {{call to 'await_suspend' implicitly required by coroutine function here}}
+    co_await c; // OK
+    co_await d; // OK
+  }
 }