Prepare for `google::protobuf::MapKey` to no longer own string keys

PiperOrigin-RevId: 675601391

python/google/protobuf/pyext/map_container.cc

@@ -96,7 +96,8 @@ static bool PyStringToSTL(PyObject* py_string, std::string* stl_string) {
   }
 }
 
-static bool PythonToMapKey(MapContainer* self, PyObject* obj, MapKey* key) {
+static bool PythonToMapKey(MapContainer* self, PyObject* obj, MapKey* key,
+                           std::string* key_string) {
   const FieldDescriptor* field_descriptor =
       self->parent_field_descriptor->message_type()->map_key();
   switch (field_descriptor->cpp_type()) {
@@ -126,11 +127,10 @@ static bool PythonToMapKey(MapContainer* self, PyObject* obj, MapKey* key) {
       break;
     }
     case FieldDescriptor::CPPTYPE_STRING: {
-      std::string str;
-      if (!PyStringToSTL(CheckString(obj, field_descriptor), &str)) {
+      if (!PyStringToSTL(CheckString(obj, field_descriptor), key_string)) {
         return false;
       }
-      key->SetStringValue(str);
+      key->SetStringValue(*key_string);
       break;
     }
     default:
@@ -334,9 +334,10 @@ PyObject* MapReflectionFriend::Contains(PyObject* _self, PyObject* key) {
 
   const Message* message = self->parent->message;
   const Reflection* reflection = message->GetReflection();
+  std::string map_key_string;
   MapKey map_key;
 
-  if (!PythonToMapKey(self, key, &map_key)) {
+  if (!PythonToMapKey(self, key, &map_key, &map_key_string)) {
     return nullptr;
   }
 
@@ -379,10 +380,11 @@ PyObject* MapReflectionFriend::ScalarMapGetItem(PyObject* _self,
 
   Message* message = self->GetMutableMessage();
   const Reflection* reflection = message->GetReflection();
+  std::string map_key_string;
   MapKey map_key;
   MapValueRef value;
 
-  if (!PythonToMapKey(self, key, &map_key)) {
+  if (!PythonToMapKey(self, key, &map_key, &map_key_string)) {
     return nullptr;
   }
 
@@ -400,10 +402,11 @@ int MapReflectionFriend::ScalarMapSetItem(PyObject* _self, PyObject* key,
 
   Message* message = self->GetMutableMessage();
   const Reflection* reflection = message->GetReflection();
+  std::string map_key_string;
   MapKey map_key;
   MapValueRef value;
 
-  if (!PythonToMapKey(self, key, &map_key)) {
+  if (!PythonToMapKey(self, key, &map_key, &map_key_string)) {
     return -1;
   }
 
@@ -593,12 +596,13 @@ int MapReflectionFriend::MessageMapSetItem(PyObject* _self, PyObject* key,
   MessageMapContainer* self = GetMessageMap(_self);
   Message* message = self->GetMutableMessage();
   const Reflection* reflection = message->GetReflection();
+  std::string map_key_string;
   MapKey map_key;
   MapValueRef value;
 
   self->version++;
 
-  if (!PythonToMapKey(self, key, &map_key)) {
+  if (!PythonToMapKey(self, key, &map_key, &map_key_string)) {
     return -1;
   }
 
@@ -635,10 +639,11 @@ PyObject* MapReflectionFriend::MessageMapGetItem(PyObject* _self,
 
   Message* message = self->GetMutableMessage();
   const Reflection* reflection = message->GetReflection();
+  std::string map_key_string;
   MapKey map_key;
   MapValueRef value;
 
-  if (!PythonToMapKey(self, key, &map_key)) {
+  if (!PythonToMapKey(self, key, &map_key, &map_key_string)) {
     return nullptr;
   }
 

src/google/protobuf/map_field.cc

@@ -338,10 +338,12 @@ void MapFieldBase::SyncMapWithRepeatedFieldNoLock() {
 
   for (const Message& elem : rep) {
     // MapKey type will be set later.
+    Reflection::ScratchSpace map_key_scratch_space;
     MapKey map_key;
     switch (key_des->cpp_type()) {
       case FieldDescriptor::CPPTYPE_STRING:
-        map_key.SetStringValue(reflection->GetString(elem, key_des));
+        map_key.SetStringValue(
+            reflection->GetStringView(elem, key_des, map_key_scratch_space));
         break;
       case FieldDescriptor::CPPTYPE_INT64:
         map_key.SetInt64Value(reflection->GetInt64(elem, key_des));

src/google/protobuf/map_field.h

@@ -112,9 +112,9 @@ class PROTOBUF_EXPORT MapKey {
     SetType(FieldDescriptor::CPPTYPE_BOOL);
     val_.bool_value = value;
   }
-  void SetStringValue(std::string val) {
+  void SetStringValue(absl::string_view val) {
     SetType(FieldDescriptor::CPPTYPE_STRING);
-    *val_.string_value.get_mutable() = std::move(val);
+    val_.string_value.get_mutable()->assign(val.data(), val.size());
   }
 
   int64_t GetInt64Value() const {

src/google/protobuf/reflection_tester.cc

@@ -7,6 +7,7 @@
 #include "google/protobuf/reflection_tester.h"
 
 #include <array>
+#include <string>
 
 #include <gtest/gtest.h>
 #include "absl/container/flat_hash_map.h"
@@ -402,6 +403,7 @@ void MapReflectionTester::SetMapFieldsViaMapReflection(Message* message) {
   MapValueConstRef map_val_const;
 
   // Add first element.
+  std::string map_key_string;
   MapKey map_key;
   map_key.SetInt32Value(0);
   EXPECT_FALSE(reflection->LookupMapValue(*message, F("map_int32_int32"),
@@ -476,7 +478,8 @@ void MapReflectionTester::SetMapFieldsViaMapReflection(Message* message) {
                                                  map_key, &map_val));
   map_val.SetBoolValue(false);
 
-  map_key.SetStringValue(long_string());
+  map_key_string = long_string();
+  map_key.SetStringValue(map_key_string);
   EXPECT_FALSE(reflection->LookupMapValue(*message, F("map_string_string"),
                                           map_key, &map_val_const));
   EXPECT_TRUE(reflection->InsertOrLookupMapValue(
@@ -576,7 +579,8 @@ void MapReflectionTester::SetMapFieldsViaMapReflection(Message* message) {
                                      &map_val);
   map_val.SetBoolValue(true);
 
-  map_key.SetStringValue(long_string_2());
+  map_key_string = long_string_2();
+  map_key.SetStringValue(map_key_string);
   reflection->InsertOrLookupMapValue(message, F("map_string_string"), map_key,
                                      &map_val);
   map_val.SetStringValue(long_string_2());
@@ -659,6 +663,7 @@ void MapReflectionTester::ModifyMapFieldsViaReflection(Message* message) {
   Message* sub_foreign_message;
 
   // Modify the second element
+  std::string map_key_string;
   MapKey map_key;
   map_key.SetInt32Value(1);
   EXPECT_FALSE(reflection->InsertOrLookupMapValue(message, F("map_int32_int32"),
@@ -725,7 +730,8 @@ void MapReflectionTester::ModifyMapFieldsViaReflection(Message* message) {
                                      &map_val);
   map_val.SetBoolValue(false);
 
-  map_key.SetStringValue(long_string_2());
+  map_key_string = long_string_2();
+  map_key.SetStringValue(map_key_string);
   reflection->InsertOrLookupMapValue(message, F("map_string_string"), map_key,
                                      &map_val);
   map_val.SetStringValue("2");