Introduce IsHpbClassThatHasExtensions

EnableIfHpbClass was too restrictive in the past; it was
toggled only if <T> was extended. This has been rectified
to toggle if T extends T::Access, which reflects the
true intention.

PiperOrigin-RevId: 693368653

csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs

@@ -1,17 +0,0 @@
-#region Copyright notice and license
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-#endregion
-
-namespace Google.Protobuf.Reflection;
-
-internal sealed partial class FeatureSetDescriptor
-{
-    // Canonical serialized form of the edition defaults, generated by embed_edition_defaults.
-    private const string DefaultsBase64 =
-        "ChMYhAciACoMCAEQAhgCIAMoATACChMY5wciACoMCAIQARgBIAIoATABChMY6AciDAgBEAEYASACKAEwASoAIOYHKOgH";
-}

hpb/extension.h

@@ -143,7 +143,7 @@ class ExtensionRegistry {
 };
 
 template <typename T, typename Extendee, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 ABSL_MUST_USE_RESULT bool HasExtension(
     Ptr<T> message,
     const ::hpb::internal::ExtensionIdentifier<Extendee, Extension>& id) {
@@ -152,7 +152,7 @@ ABSL_MUST_USE_RESULT bool HasExtension(
 }
 
 template <typename T, typename Extendee, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 ABSL_MUST_USE_RESULT bool HasExtension(
     const T* message,
     const ::hpb::internal::ExtensionIdentifier<Extendee, Extension>& id) {
@@ -160,7 +160,7 @@ ABSL_MUST_USE_RESULT bool HasExtension(
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>,
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>,
           typename = hpb::internal::EnableIfMutableProto<T>>
 void ClearExtension(
     Ptr<T> message,
@@ -171,14 +171,14 @@ void ClearExtension(
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 void ClearExtension(
     T* message, const ::hpb::internal::ExtensionIdentifier<T, Extension>& id) {
   ClearExtension(Ptr(message), id);
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>,
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>,
           typename = hpb::internal::EnableIfMutableProto<T>>
 absl::Status SetExtension(
     Ptr<T> message,
@@ -192,7 +192,7 @@ absl::Status SetExtension(
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>,
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>,
           typename = hpb::internal::EnableIfMutableProto<T>>
 absl::Status SetExtension(
     Ptr<T> message,
@@ -206,7 +206,7 @@ absl::Status SetExtension(
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>,
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>,
           typename = hpb::internal::EnableIfMutableProto<T>>
 absl::Status SetExtension(
     Ptr<T> message,
@@ -223,7 +223,7 @@ absl::Status SetExtension(
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 absl::Status SetExtension(
     T* message, const ::hpb::internal::ExtensionIdentifier<T, Extension>& id,
     const Extension& value) {
@@ -231,7 +231,7 @@ absl::Status SetExtension(
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 absl::Status SetExtension(
     T* message, const ::hpb::internal::ExtensionIdentifier<T, Extension>& id,
     Extension&& value) {
@@ -239,7 +239,7 @@ absl::Status SetExtension(
 }
 
 template <typename T, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 absl::Status SetExtension(
     T* message, const ::hpb::internal::ExtensionIdentifier<T, Extension>& id,
     Ptr<Extension> value) {
@@ -247,7 +247,7 @@ absl::Status SetExtension(
 }
 
 template <typename T, typename Extendee, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 absl::StatusOr<Ptr<const Extension>> GetExtension(
     Ptr<T> message,
     const ::hpb::internal::ExtensionIdentifier<Extendee, Extension>& id) {
@@ -264,7 +264,7 @@ absl::StatusOr<Ptr<const Extension>> GetExtension(
 }
 
 template <typename T, typename Extendee, typename Extension,
-          typename = hpb::internal::EnableIfHpbClass<T>>
+          typename = hpb::internal::EnableIfHpbClassThatHasExtensions<T>>
 decltype(auto) GetExtension(
     const T* message,
     const hpb::internal::ExtensionIdentifier<Extendee, Extension>& id) {

hpb/internal/template_help.h

@@ -35,10 +35,29 @@ template <typename T, typename U = RemovePtrT<T>,
           typename = std::enable_if_t<!std::is_const_v<U>>>
 using PtrOrRaw = T;
 
+template <typename T, typename = void>
+inline constexpr bool IsHpbClass = false;
+
+template <typename T>
+inline constexpr bool
+    IsHpbClass<T, std::enable_if_t<std::is_base_of_v<typename T::Access, T>>> =
+        true;
+
+template <typename T>
+using EnableIfHpbClass = std::enable_if_t<IsHpbClass<T>>;
+
+template <typename T, typename = void>
+inline constexpr bool IsHpbClassThatHasExtensions = false;
+
+template <typename T>
+inline constexpr bool IsHpbClassThatHasExtensions<
+    T, std::enable_if_t<std::is_base_of_v<typename T::Access, T> &&
+                        std::is_base_of_v<typename T::ExtendableType, T>>> =
+    true;
+
 template <typename T>
-using EnableIfHpbClass = std::enable_if_t<
-    std::is_base_of<typename T::Access, T>::value &&
-    std::is_base_of<typename T::Access, typename T::ExtendableType>::value>;
+using EnableIfHpbClassThatHasExtensions =
+    std::enable_if_t<IsHpbClassThatHasExtensions<T>>;
 
 template <typename T>
 using EnableIfMutableProto = std::enable_if_t<!std::is_const<T>::value>;

hpb/internal/template_help_test.cc

@@ -0,0 +1,40 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2024 Google LLC.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#include "google/protobuf/hpb/internal/template_help.h"
+
+#include <gtest/gtest.h>
+#include "google/protobuf/compiler/hpb/tests/test_model.upb.proto.h"
+
+namespace hpb_unittest::protos {
+
+class NonHpbClass {};
+
+TEST(TemplateHelp, TestIsHpbClass) {
+  static_assert(hpb::internal::IsHpbClass<TestModel>,
+                "TestModel must be an hpb class");
+  static_assert(hpb::internal::IsHpbClass<ThemeExtension>,
+                "ThemeExtension must be an hpb class");
+  static_assert(!hpb::internal::IsHpbClass<NonHpbClass>,
+                "NonHpbClass must not be an hpb class");
+  static_assert(!hpb::internal::IsHpbClass<int>,
+                "primitives like int must not be an hpb class");
+}
+
+TEST(TemplateHelp, TestIsHpbExtendedClass) {
+  static_assert(
+      hpb::internal::IsHpbClassThatHasExtensions<TestModel>,
+      "TestModel must be an hpb extension class, for it has extensions");
+  static_assert(!hpb::internal::IsHpbClassThatHasExtensions<ThemeExtension>,
+                "ThemeExtension must not have extensions");
+  static_assert(!hpb::internal::IsHpbClassThatHasExtensions<NonHpbClass>,
+                "NonHpbClass must not be an hpb extension class");
+  static_assert(!hpb::internal::IsHpbClassThatHasExtensions<int>,
+                "primitives like int must not be an hpb extension class");
+}
+
+}  // namespace hpb_unittest::protos