Upgrade input parameters in UnknownFieldSet from `const std::string&` to

`absl::string_view` to prepare the code for dropping `const std::string&` from
the interface.

PiperOrigin-RevId: 651894646

src/google/protobuf/unknown_field_set.cc

@@ -14,6 +14,7 @@
 #include "absl/log/absl_check.h"
 #include "absl/strings/cord.h"
 #include "absl/strings/internal/resize_uninitialized.h"
+#include "absl/strings/string_view.h"
 #include "google/protobuf/extension_set.h"
 #include "google/protobuf/generated_message_tctable_decl.h"
 #include "google/protobuf/generated_message_tctable_impl.h"
@@ -280,7 +281,7 @@ void UnknownField::DeepCopy(const UnknownField& other) {
 uint8_t* UnknownField::InternalSerializeLengthDelimitedNoTag(
     uint8_t* target, io::EpsCopyOutputStream* stream) const {
   ABSL_DCHECK_EQ(TYPE_LENGTH_DELIMITED, type());
-  const std::string& data = *data_.length_delimited_.string_value;
+  const absl::string_view data = *data_.length_delimited_.string_value;
   target = io::CodedOutputStream::WriteVarint32ToArray(data.size(), target);
   target = stream->WriteRaw(data.data(), data.size(), target);
   return target;

src/google/protobuf/unknown_field_set.h

@@ -22,6 +22,7 @@
 
 #include "google/protobuf/stubs/common.h"
 #include "absl/log/absl_check.h"
+#include "absl/strings/string_view.h"
 #include "google/protobuf/io/coded_stream.h"
 #include "google/protobuf/io/zero_copy_stream_impl_lite.h"
 #include "google/protobuf/message_lite.h"
@@ -119,7 +120,7 @@ class PROTOBUF_EXPORT UnknownFieldSet {
   void AddVarint(int number, uint64_t value);
   void AddFixed32(int number, uint32_t value);
   void AddFixed64(int number, uint64_t value);
-  void AddLengthDelimited(int number, const std::string& value);
+  void AddLengthDelimited(int number, absl::string_view value);
   std::string* AddLengthDelimited(int number);
   UnknownFieldSet* AddGroup(int number);
 
@@ -142,7 +143,7 @@ class PROTOBUF_EXPORT UnknownFieldSet {
   bool ParseFromCodedStream(io::CodedInputStream* input);
   bool ParseFromZeroCopyStream(io::ZeroCopyInputStream* input);
   bool ParseFromArray(const void* data, int size);
-  inline bool ParseFromString(const std::string& data) {
+  inline bool ParseFromString(const absl::string_view data) {
     return ParseFromArray(data.data(), static_cast<int>(data.size()));
   }
 
@@ -238,7 +239,7 @@ class PROTOBUF_EXPORT UnknownField {
   inline void set_varint(uint64_t value);
   inline void set_fixed32(uint32_t value);
   inline void set_fixed64(uint64_t value);
-  inline void set_length_delimited(const std::string& value);
+  inline void set_length_delimited(absl::string_view value);
   inline std::string* mutable_length_delimited();
   inline UnknownFieldSet* mutable_group();
 
@@ -304,8 +305,8 @@ inline UnknownField* UnknownFieldSet::mutable_field(int index) {
 }
 
 inline void UnknownFieldSet::AddLengthDelimited(int number,
-                                                const std::string& value) {
-  AddLengthDelimited(number)->assign(value);
+                                                const absl::string_view value) {
+  AddLengthDelimited(number)->assign(value.data(), value.size());
 }
 
 
@@ -349,9 +350,9 @@ inline void UnknownField::set_fixed64(uint64_t value) {
   assert(type() == TYPE_FIXED64);
   data_.fixed64_ = value;
 }
-inline void UnknownField::set_length_delimited(const std::string& value) {
+inline void UnknownField::set_length_delimited(const absl::string_view value) {
   assert(type() == TYPE_LENGTH_DELIMITED);
-  data_.length_delimited_.string_value->assign(value);
+  data_.length_delimited_.string_value->assign(value.data(), value.size());
 }
 inline std::string* UnknownField::mutable_length_delimited() {
   assert(type() == TYPE_LENGTH_DELIMITED);