Improve handling of unsupported view types

clang/lib/Sema/SemaInit.cpp

@@ -4996,9 +4996,14 @@ static void TryReferenceInitializationCore(Sema &S,
   // OpenCilk: If the right hand side is a hyperobject, see if the
   // left hand side wants the hyperobject or a view.
   if (T2->isHyperobjectType() && !T1->isHyperobjectType()) {
-    Sequence.AddViewLookup(T1);
-    T2 = T2.stripHyperobject();
-    cv2T2 = cv2T2.stripHyperobject();
+    // If the view of T2 is a reference type (already diagnosed)
+    // then CompareReferenceRelationship will assert fail.
+    QualType View2 = T2.stripHyperobject();
+    if (!View2->isReferenceType()) {
+      Sequence.AddViewLookup(T1);
+      T2 = View2;
+      cv2T2 = cv2T2.stripHyperobject();
+    }
   }
 
   // Compute some basic properties of the types and the initializer.

clang/lib/Sema/SemaType.cpp

@@ -1324,13 +1324,6 @@ static std::optional<unsigned> ContainsHyperobject(QualType Outer) {
   case Type::Decltype:
     Inner = cast<DecltypeType>(T)->getUnderlyingType();
     break;
-  case Type::Elaborated:
-    Inner = cast<ElaboratedType>(T)->desugar();
-    break;
-  case Type::Adjusted:
-  case Type::Decayed:
-    Inner = cast<AdjustedType>(T)->desugar();
-    break;
   case Type::Auto:
   case Type::DeducedTemplateSpecialization:
     Inner = cast<DeducedType>(T)->desugar();
@@ -1340,6 +1333,11 @@ static std::optional<unsigned> ContainsHyperobject(QualType Outer) {
   case Type::DependentTemplateSpecialization:
   case Type::PackExpansion:
   case Type::UnaryTransform:
+  case Type::LValueReference:
+  case Type::RValueReference:
+  case Type::BlockPointer:
+  case Type::FunctionProto:
+  case Type::FunctionNoProto:
     return diag::confusing_hyperobject;
   case Type::Builtin:
   case Type::TemplateTypeParm:
@@ -2495,6 +2493,9 @@ QualType Sema::BuildHyperobjectType(QualType Element, Expr *Identity,
       Diag(Loc, *Code) << Element;
   }
 
+  if (!Element->isObjectType())
+    Diag(Loc, diag::confusing_hyperobject) << Element;
+
   if (Element.isConstQualified() || Element.isVolatileQualified()) {
     Diag(Loc, diag::qualified_hyperobject) << Element;
     // Volatile reducers generate confusing diagnostics when used.

clang/test/Cilk/hyper-errors.cpp

@@ -27,6 +27,22 @@ int _Hyperobject(0) j; // expected-error{{hyperobject must have 0 or 2 callbacks
 int _Hyperobject(0,0,0,0) k; // expected-error{{hyperobject must have 0 or 2 callbacks}}
 int _Hyperobject(0, 1) x; // expected-error{{incompatible integer to pointer conversion passing 'int' to parameter of type 'void (*)(void *, void *)'}}
 
+template<typename View> struct T {
+  View _Hyperobject field;
+  // expected-error@-1{{qualified type 'const int' may not be a hyperobject}}
+  // expected-error@-2{{type 'int _Hyperobject', which contains a hyperobject, may not be a hyperobject}}
+  // expected-error@-3{{type 'int &' may not be a hyperobject}}
+  // expected-error@-4{{type 'int &' may not be a hyperobject}}
+  View &get_view() { return field; }
+  // expected-error@-1{{non-const lvalue reference to type 'int' cannot bind to a value of unrelated type 'int &_Hyperobject'}}
+  // The text of the preceding error message is unimportant.
+  // The compiler used to crash in this situation.
+  View &&get_view_xvalue() { return (View &&)field; }
+  const View &get_view_const() const { return field; }
+  T();
+  ~T();
+};
+
 void function() {
   int _Hyperobject(typo1, reduce) var1 = 0;
   // expected-error@-1{{use of undeclared identifier 'typo1'}}
@@ -35,4 +51,16 @@ void function() {
   // expected-error@-2{{use of undeclared identifier 'typo3'}}
   int _Hyperobject(0, typo4) var3 = 0;
   // expected-error@-1{{use of undeclared identifier 'typo4'}}
+  T<const int> var4;
+  // expected-note@-1{{requested here}}
+  T<int _Hyperobject> var5;
+  // expected-note@-1{{requested here}}
+  T<int> var6;
+  T<int &> var7;
+  // expected-note@-1{{requested here}}
+  int &ref1 = var6.get_view();
+  const int &ref2 = var6.get_view_const();
+  int &&ref3 = var6.get_view_xvalue();
+  var7.get_view();
+  // expected-note@-1{{requested here}}
 }