Switch C++ extension identifier to constexpr.

Add static_assert test for ExtensionNumber API.

PiperOrigin-RevId: 654129635

hpb/hpb.h

@@ -204,13 +204,12 @@ class ExtensionIdentifier : public ExtensionMiniTableProvider {
   using Extendee = ExtendeeType;
 
   constexpr explicit ExtensionIdentifier(
-      const upb_MiniTableExtension* mini_table_ext)
+      uint32_t number, const upb_MiniTableExtension* mini_table_ext)
-      : ExtensionMiniTableProvider(mini_table_ext) {}
+      : ExtensionMiniTableProvider(mini_table_ext), number_(number) {}
 
  private:
-  constexpr uint32_t number() const {
+  uint32_t number_;
-    return upb_MiniTableExtension_Number(mini_table_ext());
+  constexpr uint32_t number() const { return number_; }
-  }
   friend class PrivateAccess;
 };
 

hpb_generator/gen_extensions.cc

@@ -7,9 +7,14 @@
 
 #include "google/protobuf/compiler/hpb/gen_extensions.h"
 
+#include <cassert>
+#include <string>
+#include <vector>
+
 #include "absl/strings/str_cat.h"
-#include "google/protobuf/compiler/hpb/gen_utils.h"
 #include "google/protobuf/compiler/hpb/names.h"
+#include "google/protobuf/compiler/hpb/output.h"
+#include "google/protobuf/descriptor.h"
 
 namespace google::protobuf::hpb_generator {
 
@@ -38,55 +43,28 @@ void WriteExtensionIdentifierHeader(const protobuf::FieldDescriptor* ext,
   if (ext->extension_scope()) {
     output(
         R"cc(
-          static const ::protos::internal::ExtensionIdentifier<$0, $1> $2;
+          static constexpr ::protos::internal::ExtensionIdentifier<$0, $3> $2{
-        )cc",
+              $4, &$1};
-        ContainingTypeName(ext), CppTypeParameterName(ext), ext->name());
-  } else {
-    output(
-        R"cc(
-          extern const ::protos::internal::ExtensionIdentifier<$0, $1> $2;
-        )cc",
-        ContainingTypeName(ext), CppTypeParameterName(ext), ext->name());
-  }
-}
-
-void WriteExtensionIdentifiersHeader(
-    const std::vector<const protobuf::FieldDescriptor*>& extensions,
-    Output& output) {
-  for (const auto* ext : extensions) {
-    if (!ext->extension_scope()) {
-      WriteExtensionIdentifierHeader(ext, output);
-    }
-  }
-}
-
-void WriteExtensionIdentifier(const protobuf::FieldDescriptor* ext,
-                              Output& output) {
-  std::string mini_table_name =
-      absl::StrCat(ExtensionIdentifierBase(ext), "_", ext->name(), "_ext");
-  if (ext->extension_scope()) {
-    output(
-        R"cc(
-          const ::protos::internal::ExtensionIdentifier<$0, $3> $4::$2(&$1);
         )cc",
         ContainingTypeName(ext), mini_table_name, ext->name(),
-        CppTypeParameterName(ext), ClassName(ext->extension_scope()));
+        CppTypeParameterName(ext), ext->number());
   } else {
     output(
         R"cc(
-          const ::protos::internal::ExtensionIdentifier<$0, $3> $2(&$1);
+          inline constexpr ::protos::internal::ExtensionIdentifier<$0, $3> $2{
+              $4, &$1};
         )cc",
         ContainingTypeName(ext), mini_table_name, ext->name(),
-        CppTypeParameterName(ext));
+        CppTypeParameterName(ext), ext->number());
   }
 }
 
-void WriteExtensionIdentifiers(
+void WriteExtensionIdentifiersHeader(
     const std::vector<const protobuf::FieldDescriptor*>& extensions,
     Output& output) {
   for (const auto* ext : extensions) {
     if (!ext->extension_scope()) {
-      WriteExtensionIdentifier(ext, output);
+      WriteExtensionIdentifierHeader(ext, output);
     }
   }
 }

hpb_generator/gen_extensions.h

@@ -8,8 +8,8 @@
 #ifndef PROTOBUF_COMPILER_HBP_GEN_EXTENSIONS_H_
 #define PROTOBUF_COMPILER_HBP_GEN_EXTENSIONS_H_
 
-#include "google/protobuf/descriptor.h"
 #include "google/protobuf/compiler/hpb/output.h"
+#include "google/protobuf/descriptor.h"
 
 namespace google::protobuf::hpb_generator {
 
@@ -20,12 +20,6 @@ void WriteExtensionIdentifiersHeader(
     Output& output);
 void WriteExtensionIdentifierHeader(const protobuf::FieldDescriptor* ext,
                                     Output& output);
-void WriteExtensionIdentifiers(
-    const std::vector<const protobuf::FieldDescriptor*>& extensions,
-    Output& output);
-void WriteExtensionIdentifier(const protobuf::FieldDescriptor* ext,
-                              Output& output);
-
 }  // namespace protobuf
 }  // namespace google::hpb_generator
 

hpb_generator/gen_messages.cc

@@ -15,15 +15,14 @@
 #include "absl/strings/ascii.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
-#include "google/protobuf/descriptor.h"
 #include "google/protobuf/compiler/hpb/gen_accessors.h"
 #include "google/protobuf/compiler/hpb/gen_enums.h"
 #include "google/protobuf/compiler/hpb/gen_extensions.h"
 #include "google/protobuf/compiler/hpb/gen_utils.h"
 #include "google/protobuf/compiler/hpb/names.h"
 #include "google/protobuf/compiler/hpb/output.h"
+#include "google/protobuf/descriptor.h"
 #include "upb_generator/common.h"
-#include "upb_generator/file_layout.h"
 
 namespace google::protobuf::hpb_generator {
 
@@ -48,10 +47,6 @@ void WriteInternalForwardDeclarationsInHeader(
     const protobuf::Descriptor* message, Output& output);
 void WriteDefaultInstanceHeader(const protobuf::Descriptor* message,
                                 Output& output);
-void WriteExtensionIdentifiersImplementation(
-    const protobuf::Descriptor* message,
-    const std::vector<const protobuf::FieldDescriptor*>& file_exts,
-    Output& output);
 void WriteUsingEnumsInHeader(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::EnumDescriptor*>& file_enums,
@@ -457,8 +452,6 @@ void WriteMessageImplementation(
           }
         )cc",
         ClassName(descriptor));
-
-    WriteExtensionIdentifiersImplementation(descriptor, file_exts, output);
   }
 }
 
@@ -486,18 +479,6 @@ void WriteExtensionIdentifiersInClassHeader(
   }
 }
 
-void WriteExtensionIdentifiersImplementation(
-    const protobuf::Descriptor* message,
-    const std::vector<const protobuf::FieldDescriptor*>& file_exts,
-    Output& output) {
-  for (auto* ext : file_exts) {
-    if (ext->extension_scope() &&
-        ext->extension_scope()->full_name() == message->full_name()) {
-      WriteExtensionIdentifier(ext, output);
-    }
-  }
-}
-
 void WriteUsingEnumsInHeader(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::EnumDescriptor*>& file_enums,

hpb_generator/protoc-gen-upb-protos.cc

@@ -13,14 +13,14 @@
 
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/compiler/code_generator.h"
-#include "google/protobuf/compiler/plugin.h"
-#include "google/protobuf/descriptor.h"
 #include "google/protobuf/compiler/hpb/gen_enums.h"
 #include "google/protobuf/compiler/hpb/gen_extensions.h"
 #include "google/protobuf/compiler/hpb/gen_messages.h"
 #include "google/protobuf/compiler/hpb/gen_utils.h"
 #include "google/protobuf/compiler/hpb/names.h"
 #include "google/protobuf/compiler/hpb/output.h"
+#include "google/protobuf/compiler/plugin.h"
+#include "google/protobuf/descriptor.h"
 
 namespace google::protobuf::hpb_generator {
 namespace {
@@ -211,7 +211,6 @@ void WriteSource(const protobuf::FileDescriptor* file, Output& output,
   WriteMessageImplementations(file, output);
   const std::vector<const protobuf::FieldDescriptor*> this_file_exts =
       SortedExtensions(file);
-  WriteExtensionIdentifiers(this_file_exts, output);
   WriteEndNamespace(file, output);
 
   output("#include \"upb/port/undef.inc\"\n\n");

hpb_generator/tests/test_generated.cc

@@ -1242,6 +1242,8 @@ TEST(CppGeneratedCode, FieldNumberConstants) {
 }
 
 TEST(CppGeneratedCode, ExtensionFieldNumberConstant) {
+  static_assert(::protos::ExtensionNumber(ThemeExtension::theme_extension) ==
+                12003);
   EXPECT_EQ(12003, ::protos::ExtensionNumber(ThemeExtension::theme_extension));
 }