From 60c7e905cc289504828ea3f50062481c55345080 Mon Sep 17 00:00:00 2001
From: "John F. Carr" <jfc@mit.edu>
Date: Fri, 8 Dec 2023 14:15:42 -0500
Subject: [PATCH] Do not process template arguments when checking for recursive
 hyperobjects

---
 clang/lib/Sema/SemaType.cpp | 31 ++-----------------------------
 clang/test/Cilk/223.cpp     | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 29 deletions(-)
 create mode 100644 clang/test/Cilk/223.cpp

diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index e85b0711de68..0cff893f0c0d 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -1294,35 +1294,6 @@ static std::optional<unsigned> ContainsHyperobject(QualType Outer) {
     break;
   case Type::Record: {
     const RecordDecl *Decl = cast<RecordType>(T)->getDecl();
-    // TODO: There must be a better way to do this.
-    // A hyperobject might sneak in without being explicitly
-    // declared in the template.
-    if (auto Spec = dyn_cast<ClassTemplateSpecializationDecl>(Decl)) {
-      if (ClassTemplateDecl *Inner = Spec->getSpecializedTemplate())
-        if (auto O = DeclContainsHyperobject(Inner->getTemplatedDecl()))
-          return O;
-      const TemplateArgumentList &Args = Spec->getTemplateArgs();
-      for (unsigned I = 0; I < Args.size(); ++I) {
-        const TemplateArgument &Arg = Args.get(I);
-        switch (Arg.getKind()) {
-        case TemplateArgument::Declaration:
-          if (auto O = ContainsHyperobject(Arg.getAsDecl()->getType()))
-            return O;
-          break;
-        case TemplateArgument::Type:
-          if (auto O = ContainsHyperobject(Arg.getAsType()))
-            return O;
-          break;
-        case TemplateArgument::Integral:
-        case TemplateArgument::NullPtr:
-        case TemplateArgument::Null:
-          break;
-        default:
-          return diag::confusing_hyperobject;
-        }
-      }
-      return std::optional<unsigned>();
-    }
     if (const RecordDecl *Def = Decl->getDefinition())
       return DeclContainsHyperobject(Def);
     return diag::confusing_hyperobject;
@@ -1362,6 +1333,8 @@ static std::optional<unsigned> ContainsHyperobject(QualType Outer) {
 }
 
 static std::optional<unsigned> DeclContainsHyperobject(const RecordDecl *Decl) {
+  if (Decl->isInvalidDecl())
+    return std::optional<unsigned>();
   for (const FieldDecl *FD : Decl->fields())
     if (std::optional<unsigned> O = ContainsHyperobject(FD->getType()))
       return O;
diff --git a/clang/test/Cilk/223.cpp b/clang/test/Cilk/223.cpp
new file mode 100644
index 000000000000..7e7805c801f8
--- /dev/null
+++ b/clang/test/Cilk/223.cpp
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 %s -x c++ -O1 -fopencilk -verify -fsyntax-only
+template <class T>
+class A { };
+
+class B {
+  A<B> a;
+};
+
+void identity(void* view) {}
+void reduce(void* l, void* r) {}
+
+B _Hyperobject(identity, reduce) b;
+
+template <class T>
+class C { T _Hyperobject *field; };
+// expected-error@-1{{incomplete type 'D' may not be a hyperobject}}
+
+class D { // expected-note{{}}}
+  C<D> a; // expected-note{{}}}
+};
+
+D _Hyperobject(identity, reduce) d;