In edition 2024, Enum_Name(value) functions return absl::string_view by default.

Added enum feature `enum_name_uses_string_view` to turn back to the old behavior returning `const std::string&`.

PiperOrigin-RevId: 655637240

Author: protobuf-github-bot

editions/generated_files_test.cc

@@ -146,7 +146,11 @@ TEST(Generated, EditionDefaults2023InternalFeatures) {
                 utf8_validation: VERIFY
                 message_encoding: LENGTH_PREFIXED
                 json_format: ALLOW
-                [pb.cpp] { legacy_closed_enum: false string_type: STRING }
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  string_type: STRING
+                  enum_name_uses_string_view: false
+                }
               )pb"));
 }
 

src/google/protobuf/compiler/cpp/enum.cc

@@ -24,6 +24,7 @@
 #include "absl/container/btree_set.h"
 #include "absl/container/flat_hash_map.h"
 #include "absl/strings/str_cat.h"
+#include "google/protobuf/compiler/cpp/generator.h"
 #include "google/protobuf/compiler/cpp/helpers.h"
 #include "google/protobuf/compiler/cpp/names.h"
 #include "google/protobuf/descriptor.h"
@@ -49,6 +50,11 @@ absl::flat_hash_map<absl::string_view, std::string> EnumVars(
        enum_->containing_type() == nullptr ? "" : absl::StrCat(classname, "_")},
       {"kMin", absl::StrCat(min->number())},
       {"kMax", absl::StrCat(max->number())},
+      {"return_type", CppGenerator::GetResolvedSourceFeatures(*enum_)
+                              .GetExtension(::pb::cpp)
+                              .enum_name_uses_string_view()
+                          ? "::absl::string_view"
+                          : "const std::string&"},
   };
 }
 
@@ -182,7 +188,7 @@ void EnumGenerator::GenerateDefinition(io::Printer* p) {
     )cc");
   } else {
     p->Emit(R"cc(
-      const std::string& $Msg_Enum$_Name($Msg_Enum$ value);
+      $return_type$ $Msg_Enum$_Name($Msg_Enum$ value);
     )cc");
   }
 
@@ -204,7 +210,7 @@ void EnumGenerator::GenerateDefinition(io::Printer* p) {
   if (should_cache_ || !has_reflection_) {
     p->Emit({{"static_assert", write_assert}}, R"cc(
       template <typename T>
-      const std::string& $Msg_Enum$_Name(T value) {
+      $return_type$ $Msg_Enum$_Name(T value) {
         $static_assert$;
         return $Msg_Enum$_Name(static_cast<$Msg_Enum$>(value));
       }
@@ -216,7 +222,7 @@ void EnumGenerator::GenerateDefinition(io::Printer* p) {
       // pointers, so if the enum values are sparse, it's not worth it.
       p->Emit(R"cc(
         template <>
-        inline const std::string& $Msg_Enum$_Name($Msg_Enum$ value) {
+        inline $return_type$ $Msg_Enum$_Name($Msg_Enum$ value) {
           return ::$proto_ns$::internal::NameOfDenseEnum<$Msg_Enum$_descriptor,
                                                          $kMin$, $kMax$>(
               static_cast<int>(value));
@@ -226,7 +232,7 @@ void EnumGenerator::GenerateDefinition(io::Printer* p) {
   } else {
     p->Emit({{"static_assert", write_assert}}, R"cc(
       template <typename T>
-      const std::string& $Msg_Enum$_Name(T value) {
+      $return_type$ $Msg_Enum$_Name(T value) {
         $static_assert$;
         return ::$proto_ns$::internal::NameOfEnum($Msg_Enum$_descriptor(), value);
       }
@@ -322,7 +328,7 @@ void EnumGenerator::GenerateSymbolImports(io::Printer* p) const {
 
   p->Emit(R"cc(
     template <typename T>
-    static inline const std::string& $Enum$_Name(T value) {
+    static inline $return_type$ $Enum$_Name(T value) {
       return $Msg_Enum$_Name(value);
     }
     static inline bool $Enum$_Parse(absl::string_view name, $Enum_$* value) {
@@ -514,7 +520,7 @@ void EnumGenerator::GenerateMethods(int idx, io::Printer* p) {
               $entries_by_number$,
           };
 
-          const std::string& $Msg_Enum$_Name($Msg_Enum$ value) {
+          $return_type$ $Msg_Enum$_Name($Msg_Enum$ value) {
             static const bool kDummy =
                 ::$proto_ns$::internal::InitializeEnumStrings(
                     $Msg_Enum$_entries, $Msg_Enum$_entries_by_number,

src/google/protobuf/cpp_edition_defaults.h

@@ -5,7 +5,7 @@
 // the C++ runtime.  This is used for feature resolution under Editions.
 // NOLINTBEGIN
 // clang-format off
-#define PROTOBUF_INTERNAL_CPP_EDITION_DEFAULTS "\n\035\030\204\007\"\003\302>\000*\023\010\001\020\002\030\002 \003(\0010\002\302>\004\010\001\020\003\n\035\030\347\007\"\003\302>\000*\023\010\002\020\001\030\001 \002(\0010\001\302>\004\010\000\020\003\n\035\030\350\007\"\023\010\001\020\001\030\001 \002(\0010\001\302>\004\010\000\020\003*\003\302>\000\n\035\030\351\007\"\023\010\001\020\001\030\001 \002(\0010\001\302>\004\010\000\020\001*\003\302>\000 \346\007(\351\007"
+#define PROTOBUF_INTERNAL_CPP_EDITION_DEFAULTS "\n\037\030\204\007\"\003\302>\000*\025\010\001\020\002\030\002 \003(\0010\002\302>\006\010\001\020\003\030\000\n\037\030\347\007\"\003\302>\000*\025\010\002\020\001\030\001 \002(\0010\001\302>\006\010\000\020\003\030\000\n\037\030\350\007\"\023\010\001\020\001\030\001 \002(\0010\001\302>\004\010\000\020\003*\005\302>\002\030\000\n\037\030\351\007\"\025\010\001\020\001\030\001 \002(\0010\001\302>\006\010\000\020\001\030\001*\003\302>\000 \346\007(\351\007"
 // clang-format on
 // NOLINTEND