r304373 - [coroutines] Fix checking for prvalue-ness of `await_suspend` return type

[Eric Fiselier via cfe-commits]

Author: ericwf
Date: Wed May 31 18:41:11 2017
New Revision: 304373

URL: http://llvm.org/viewvc/llvm-project?rev=304373&view=rev
Log:
[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

Modified:
    cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
    cfe/trunk/lib/Sema/SemaCoroutine.cpp
    cfe/trunk/test/SemaCXX/coroutines.cpp

Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=304373&r1=304372&r2=304373&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Wed May 31 18:41:11 2017
@@ -8979,10 +8979,10 @@ def err_coroutine_promise_new_requires_n
 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'"
 >;
 }
 

Modified: cfe/trunk/lib/Sema/SemaCoroutine.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaCoroutine.cpp?rev=304373&r1=304372&r2=304373&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaCoroutine.cpp (original)
+++ cfe/trunk/lib/Sema/SemaCoroutine.cpp Wed May 31 18:41:11 2017
@@ -391,8 +391,11 @@ static ReadySuspendResumeResult buildCoa
     // [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;

Modified: cfe/trunk/test/SemaCXX/coroutines.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/coroutines.cpp?rev=304373&r1=304372&r2=304373&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/coroutines.cpp (original)
+++ cfe/trunk/test/SemaCXX/coroutines.cpp Wed May 31 18:41:11 2017
@@ -840,12 +840,12 @@ coro<bad_promise_no_return_func> no_retu
 
 struct bad_await_suspend_return {
   bool await_ready();
-  // expected-error at +1 {{the return type of 'await_suspend' is required to be 'void' or 'bool' (have 'char')}}
+  // expected-error at +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 at +1 {{the return type of 'await_ready' is required to be contextually convertible to 'bool'}}
+  // expected-note at +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 at +2 {{return type of 'await_suspend' is required to be 'void' or 'bool' (have 'bool &')}}
+  // expected-error at +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
+  }
 }