Merge tag 'refs/tags/sync-piper' into sync-stage

conformance/conformance_test.cc

@@ -350,7 +350,17 @@ bool ConformanceTestSuite::CheckSetEmpty(
     StringAppendF(&output_, "\n");
 
     if (!write_to_file.empty()) {
-      std::ofstream os(write_to_file);
+      std::string full_filename;
+      const std::string* filename = &write_to_file;
+      if (!output_dir_.empty()) {
+        full_filename = output_dir_;
+        if (*output_dir_.rbegin() != '/') {
+          full_filename.push_back('/');
+        }
+        full_filename += write_to_file;
+        filename = &full_filename;
+      }
+      std::ofstream os(*filename);
       if (os) {
         for (std::set<string>::const_iterator iter = set_to_check.begin();
              iter != set_to_check.end(); ++iter) {
@@ -358,7 +368,7 @@ bool ConformanceTestSuite::CheckSetEmpty(
         }
       } else {
         StringAppendF(&output_, "Failed to open file: %s\n",
-                      write_to_file.c_str());
+                      filename->c_str());
       }
     }
 

conformance/conformance_test.h

@@ -174,6 +174,11 @@ class ConformanceTestSuite {
     failure_list_flag_name_ = failure_list_flag_name;
   }
 
+  // Sets the path of the output directory.
+  void SetOutputDir(const char* output_dir) {
+    output_dir_ = output_dir;
+  }
+
   // Run all the conformance tests against the given test runner.
   // Test output will be stored in "output".
   //
@@ -296,6 +301,7 @@ class ConformanceTestSuite {
   bool verbose_;
   bool enforce_recommended_;
   std::string output_;
+  std::string output_dir_;
   std::string failure_list_flag_name_;
   std::string failure_list_filename_;
 

conformance/conformance_test_runner.cc

@@ -141,6 +141,9 @@ void UsageError() {
           "                              strictly conforming to protobuf\n");
   fprintf(stderr,
           "                              spec.\n");
+  fprintf(stderr,
+          "  --output_dir                <dirname> Directory to write\n"
+          "                              output files.\n");
   exit(1);
 }
 
@@ -208,6 +211,9 @@ int ForkPipeRunner::Run(
         suite->SetVerbose(true);
       } else if (strcmp(argv[arg], "--enforce_recommended") == 0) {
         suite->SetEnforceRecommended(true);
+      } else if (strcmp(argv[arg], "--output_dir") == 0) {
+        if (++arg == argc) UsageError();
+        suite->SetOutputDir(argv[arg]);
       } else if (argv[arg][0] == '-') {
         bool recognized_flag = false;
         for (ConformanceTestSuite* suite : suites) {

conformance/failure_list_js.txt

@@ -0,0 +1,104 @@
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.INT64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.INT64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.INT64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataScalarBinary.FIXED64[2].ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataScalarBinary.INT64[2].ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataScalarBinary.SFIXED64[2].ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataScalarBinary.SINT64[2].ProtobufOutput
+Recommended.Proto2.ProtobufInput.ValidDataScalarBinary.UINT64[2].ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.INT64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.INT64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.INT64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.DefaultOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.PackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.UnpackedOutput.ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataScalarBinary.FIXED64[2].ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataScalarBinary.INT64[2].ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataScalarBinary.SFIXED64[2].ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataScalarBinary.SINT64[2].ProtobufOutput
+Recommended.Proto3.ProtobufInput.ValidDataScalarBinary.UINT64[2].ProtobufOutput
+Required.Proto2.ProtobufInput.RepeatedScalarSelectsLast.FIXED64.ProtobufOutput
+Required.Proto2.ProtobufInput.RepeatedScalarSelectsLast.UINT64.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.INT64.PackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataScalar.FIXED64[2].ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataScalar.INT64[2].ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataScalar.SFIXED64[2].ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataScalar.SINT64[2].ProtobufOutput
+Required.Proto2.ProtobufInput.ValidDataScalar.UINT64[2].ProtobufOutput
+Required.Proto3.ProtobufInput.RepeatedScalarSelectsLast.FIXED64.ProtobufOutput
+Required.Proto3.ProtobufInput.RepeatedScalarSelectsLast.UINT64.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.PackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.FIXED64.UnpackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.INT64.PackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.INT64.UnpackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.PackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.SFIXED64.UnpackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.SINT64.PackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.SINT64.UnpackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.UINT64.PackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataRepeated.UINT64.UnpackedInput.ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataScalar.FIXED64[2].ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataScalar.INT64[2].ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataScalar.SFIXED64[2].ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataScalar.SINT64[2].ProtobufOutput
+Required.Proto3.ProtobufInput.ValidDataScalar.UINT64[2].ProtobufOutput

java/core/src/main/java/com/google/protobuf/ArrayDecoders.java

@@ -45,14 +45,15 @@ import java.io.IOException;
  */
 @CheckReturnValue
 final class ArrayDecoders {
+
+  private ArrayDecoders() {
+  }
+
   /**
    * A helper used to return multiple values in a Java function. Java doesn't natively support
    * returning multiple values in a function. Creating a new Object to hold the return values will
    * be too expensive. Instead, we pass a Registers instance to functions that want to return
    * multiple values and let the function set the return value in this Registers instance instead.
-   *
-   * <p>TODO(xiaofeng): This could be merged into CodedInputStream or CodedInputStreamReader which
-   * is already being passed through all the parsing routines.
    */
   static final class Registers {
     public int int1;

java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java

@@ -692,7 +692,7 @@ public abstract class GeneratedMessageLite<
       // The wire format for MessageSet is:
       //   message MessageSet {
       //     repeated group Item = 1 {
-      //       required int32 typeId = 2;
+      //       required uint32 typeId = 2;
       //       required bytes message = 3;
       //     }
       //   }

java/core/src/main/java/com/google/protobuf/Internal.java

@@ -259,7 +259,9 @@ public final class Internal {
 
   /** Helper method for implementing {@link Message#equals(Object)} for bytes field. */
   public static boolean equals(List<byte[]> a, List<byte[]> b) {
-    if (a.size() != b.size()) return false;
+    if (a.size() != b.size()) {
+      return false;
+    }
     for (int i = 0; i < a.size(); ++i) {
       if (!Arrays.equals(a.get(i), b.get(i))) {
         return false;

java/core/src/main/java/com/google/protobuf/MessageReflection.java

@@ -882,7 +882,7 @@ class MessageReflection {
     // The wire format for MessageSet is:
     //   message MessageSet {
     //     repeated group Item = 1 {
-    //       required int32 typeId = 2;
+    //       required uint32 typeId = 2;
     //       required bytes message = 3;
     //     }
     //   }

java/core/src/main/java/com/google/protobuf/MessageSetSchema.java

@@ -300,7 +300,7 @@ final class MessageSetSchema<T> implements Schema<T> {
     // The wire format for MessageSet is:
     //   message MessageSet {
     //     repeated group Item = 1 {
-    //       required int32 typeId = 2;
+    //       required uint32 typeId = 2;
     //       required bytes message = 3;
     //     }
     //   }

java/core/src/main/java/com/google/protobuf/TextFormat.java

@@ -49,7 +49,7 @@ import java.util.regex.Pattern;
 
 /**
  * Provide text parsing and formatting support for proto2 instances. The implementation largely
- * follows google/protobuf/text_format.cc.
+ * follows text_format.cc.
  *
  * @author wenboz@google.com Wenbo Zhu
  * @author kenton@google.com Kenton Varda
@@ -2307,7 +2307,7 @@ public final class TextFormat {
    * Un-escape a byte sequence as escaped using {@link #escapeBytes(ByteString)}. Two-digit hex
    * escapes (starting with "\x") are also recognized.
    */
-  public static ByteString unescapeBytes(final CharSequence charString)
+  public static ByteString unescapeBytes(CharSequence charString)
       throws InvalidEscapeSequenceException {
     // First convert the Java character sequence to UTF-8 bytes.
     ByteString input = ByteString.copyFromUtf8(charString.toString());
@@ -2444,9 +2444,10 @@ public final class TextFormat {
                           + "' is not a valid code point value");
                 }
                 Character.UnicodeBlock unicodeBlock = Character.UnicodeBlock.of(codepoint);
-                if (unicodeBlock.equals(Character.UnicodeBlock.LOW_SURROGATES)
+                if (unicodeBlock != null
+                        && (unicodeBlock.equals(Character.UnicodeBlock.LOW_SURROGATES)
                     || unicodeBlock.equals(Character.UnicodeBlock.HIGH_SURROGATES)
-                    || unicodeBlock.equals(Character.UnicodeBlock.HIGH_PRIVATE_USE_SURROGATES)) {
+                    || unicodeBlock.equals(Character.UnicodeBlock.HIGH_PRIVATE_USE_SURROGATES))) {
                   throw new InvalidEscapeSequenceException(
                       "Invalid escape sequence: '\\U"
                           + input.substring(i, i + 8).toStringUtf8()

java/core/src/main/java/com/google/protobuf/TextFormatEscaper.java

@@ -30,7 +30,24 @@
 
 package com.google.protobuf;
 
-/** Provide text format escaping support for proto2 instances. */
+/**
+ * Provide text format escaping of proto instances. These ASCII characters are escaped:
+ *
+ * ASCII #7   (bell) --> \a
+ * ASCII #8   (backspace) --> \b
+ * ASCII #9   (horizontal tab) --> \t
+ * ASCII #10  (linefeed) --> \n
+ * ASCII #11  (vertical tab) --> \v
+ * ASCII #13  (carriage return) --> \r
+ * ASCII #12  (formfeed) --> \f
+ * ASCII #34  (apostrophe) --> \'
+ * ASCII #39  (straight double quote) --> \"
+ * ASCII #92  (backslash) --> \\
+ *
+ * Other printable ASCII characters between 32 and 127 inclusive are output as is, unescaped.
+ * Other ASCII characters less than 32 and all Unicode characters 128 or greater are
+ * first encoded as UTF-8, then each byte is escaped individually as a 3-digit octal escape.
+ */
 final class TextFormatEscaper {
   private TextFormatEscaper() {}
 
@@ -41,17 +58,13 @@ final class TextFormatEscaper {
   }
 
   /**
-   * Escapes bytes in the format used in protocol buffer text format, which is the same as the
-   * format used for C string literals. All bytes that are not printable 7-bit ASCII characters are
-   * escaped, as well as backslash, single-quote, and double-quote characters. Characters for which
-   * no defined short-hand escape sequence is defined will be escaped using 3-digit octal sequences.
+   * Backslash escapes bytes in the format used in protocol buffer text format.
    */
-  static String escapeBytes(final ByteSequence input) {
+  static String escapeBytes(ByteSequence input) {
     final StringBuilder builder = new StringBuilder(input.size());
     for (int i = 0; i < input.size(); i++) {
-      final byte b = input.byteAt(i);
+      byte b = input.byteAt(i);
       switch (b) {
-          // Java does not recognize \a or \v, apparently.
         case 0x07:
           builder.append("\\a");
           break;
@@ -100,10 +113,7 @@ final class TextFormatEscaper {
   }
 
   /**
-   * Escapes bytes in the format used in protocol buffer text format, which is the same as the
-   * format used for C string literals. All bytes that are not printable 7-bit ASCII characters are
-   * escaped, as well as backslash, single-quote, and double-quote characters. Characters for which
-   * no defined short-hand escape sequence is defined will be escaped using 3-digit octal sequences.
+   * Backslash escapes bytes in the format used in protocol buffer text format.
    */
   static String escapeBytes(final ByteString input) {
     return escapeBytes(
@@ -137,16 +147,14 @@ final class TextFormatEscaper {
   }
 
   /**
-   * Like {@link #escapeBytes(ByteString)}, but escapes a text string. Non-ASCII characters are
-   * first encoded as UTF-8, then each byte is escaped individually as a 3-digit octal escape. Yes,
-   * it's weird.
+   * Like {@link #escapeBytes(ByteString)}, but escapes a text string.
    */
-  static String escapeText(final String input) {
+  static String escapeText(String input) {
     return escapeBytes(ByteString.copyFromUtf8(input));
   }
 
   /** Escape double quotes and backslashes in a String for unicode output of a message. */
-  static String escapeDoubleQuotesAndBackslashes(final String input) {
+  static String escapeDoubleQuotesAndBackslashes(String input) {
     return input.replace("\\", "\\\\").replace("\"", "\\\"");
   }
 }

java/core/src/main/java/com/google/protobuf/Utf8.java

@@ -64,9 +64,9 @@ import java.nio.ByteBuffer;
  * <em>Well Formed UTF-8 Byte Sequences</em>.
  *
  * <p>This class supports decoding of partial byte sequences, so that the bytes in a complete UTF-8
- * byte sequences can be stored in multiple segments. Methods typically return {@link #MALFORMED} if
- * the partial byte sequence is definitely not well-formed, {@link #COMPLETE} if it is well-formed
- * in the absence of additional input, or if the byte sequence apparently terminated in the middle
+ * byte sequence can be stored in multiple segments. Methods typically return {@link #MALFORMED} if
+ * the partial byte sequence is definitely not well-formed; {@link #COMPLETE} if it is well-formed
+ * in the absence of additional input; or, if the byte sequence apparently terminated in the middle
  * of a character, an opaque integer "state" value containing enough information to decode the
  * character when passed to a subsequent invocation of a partial decoding method.
  *

java/core/src/test/java/com/google/protobuf/TextFormatTest.java

@@ -170,6 +170,13 @@ public class TextFormatTest {
     assertThat(javaText).isEqualTo(ALL_FIELDS_SET_TEXT);
   }
 
+  @Test
+  // https://github.com/protocolbuffers/protobuf/issues/9447
+  public void testCharacterNotInUnicodeBlock() throws TextFormat.InvalidEscapeSequenceException {
+    ByteString actual = TextFormat.unescapeBytes("\\U000358da");
+    assertThat(actual.size()).isEqualTo(4);
+  }
+
   /** Print TestAllTypes as Builder and compare with golden file. */
   @Test
   public void testPrintMessageBuilder() throws Exception {

java/kotlin/src/main/kotlin/com/google/protobuf/Anies.kt

@@ -0,0 +1,45 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf.kotlin
+
+import com.google.protobuf.Any as ProtoAny
+import com.google.protobuf.Message
+
+/** Returns `true` if this [com.google.protobuf.Any] contains a message of type `T`. */
+inline fun <reified T : Message> ProtoAny.isA(): Boolean = this.`is`(T::class.java)
+
+/**
+ * Returns the message of type `T` encoded in this [com.google.protobuf.Any].
+ *
+ * @throws InvalidProtocolBufferException if this [com.google.protobuf.Any] does not contain a `T`
+ * message.
+ */
+inline fun <reified T : Message> ProtoAny.unpack(): T = unpack(T::class.java)

java/kotlin/src/test/kotlin/com/google/protobuf/AniesTest.kt

@@ -0,0 +1,70 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf.kotlin
+
+import com.google.common.truth.Truth.assertThat
+import com.google.protobuf.Any as ProtoAny
+import com.google.protobuf.InvalidProtocolBufferException
+import protobuf_unittest.UnittestProto.BoolMessage
+import protobuf_unittest.UnittestProto.Int32Message
+import protobuf_unittest.int32Message
+import kotlin.test.assertFailsWith
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+/** Tests for extension methods on [ProtoAny]. */
+@RunWith(JUnit4::class)
+class AniesTest {
+  companion object {
+    val anAny = ProtoAny.pack(int32Message { data = 5 })
+  }
+
+  @Test
+  fun isA_Positive() {
+    assertThat(anAny.isA<Int32Message>()).isTrue()
+  }
+
+  @Test
+  fun isA_Negative() {
+    assertThat(anAny.isA<BoolMessage>()).isFalse()
+  }
+
+  @Test
+  fun unpackValid() {
+    assertThat(anAny.unpack<Int32Message>().data).isEqualTo(5)
+  }
+
+  @Test
+  fun unpackInvalid() {
+    assertFailsWith<InvalidProtocolBufferException> { anAny.unpack<BoolMessage>() }
+  }
+}

python/google/protobuf/internal/descriptor_pool_test.py

@@ -541,7 +541,13 @@ class DescriptorPoolTestBase(object):
       pool._AddExtensionDescriptor(
           file_descriptor.extensions_by_name['optional_int32_extension'])
       pool.Add(unittest_fd)
-      pool.Add(conflict_fd)
+      with warnings.catch_warnings(record=True) as w:
+        warnings.simplefilter('always')
+        pool.Add(conflict_fd)
+        self.assertTrue(len(w))
+        self.assertIs(w[0].category, RuntimeWarning)
+        self.assertIn('Conflict register for file "other_file": ',
+                      str(w[0].message))
       pool.FindFileByName(unittest_fd.name)
       with self.assertRaises(TypeError):
         pool.FindFileByName(conflict_fd.name)

python/google/protobuf/json_format.py

@@ -95,7 +95,8 @@ def MessageToJson(
     sort_keys=False,
     use_integers_for_enums=False,
     descriptor_pool=None,
-    float_precision=None):
+    float_precision=None,
+    ensure_ascii=True):
   """Converts protobuf message to JSON format.
 
   Args:
@@ -114,6 +115,8 @@ def MessageToJson(
     descriptor_pool: A Descriptor Pool for resolving types. If None use the
         default.
     float_precision: If set, use this to specify float field valid digits.
+    ensure_ascii: If True, strings with non-ASCII characters are escaped.
+        If False, Unicode strings are returned unchanged.
 
   Returns:
     A string containing the JSON formatted protocol buffer message.
@@ -124,7 +127,7 @@ def MessageToJson(
       use_integers_for_enums,
       descriptor_pool,
       float_precision=float_precision)
-  return printer.ToJsonString(message, indent, sort_keys)
+  return printer.ToJsonString(message, indent, sort_keys, ensure_ascii)
 
 
 def MessageToDict(
@@ -190,9 +193,10 @@ class _Printer(object):
     else:
       self.float_format = None
 
-  def ToJsonString(self, message, indent, sort_keys):
+  def ToJsonString(self, message, indent, sort_keys, ensure_ascii):
     js = self._MessageToJsonObject(message)
-    return json.dumps(js, indent=indent, sort_keys=sort_keys)
+    return json.dumps(
+        js, indent=indent, sort_keys=sort_keys, ensure_ascii=ensure_ascii)
 
   def _MessageToJsonObject(self, message):
     """Converts message to an object according to Proto3 JSON Specification."""

python/google/protobuf/pyext/message.cc

@@ -1002,7 +1002,7 @@ int DeleteRepeatedField(
     }
   }
 
-  Arena* arena = Arena::InternalHelper<Message>::GetArenaForAllocation(message);
+  Arena* arena = Arena::InternalGetArenaForAllocation(message);
   GOOGLE_DCHECK_EQ(arena, nullptr)
       << "python protobuf is expected to be allocated from heap";
   // Remove items, starting from the end.

python/google/protobuf/pyext/unknown_fields.cc

@@ -138,8 +138,9 @@ static void Dealloc(PyObject* pself) {
     reinterpret_cast<CMessage*>(self->parent)->unknown_field_set = nullptr;
   }
   Py_CLEAR(self->parent);
+  auto* py_type = Py_TYPE(pself);
   self->~PyUnknownFields();
-  Py_TYPE(pself)->tp_free(pself);
+  py_type->tp_free(pself);
 }
 
 static PySequenceMethods SqMethods = {

src/google/protobuf/any.cc

@@ -49,10 +49,8 @@ bool AnyMetadata::PackFrom(Arena* arena, const Message& message) {
 bool AnyMetadata::PackFrom(Arena* arena, const Message& message,
                            StringPiece type_url_prefix) {
   type_url_->Set(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyString(),
       GetTypeUrl(message.GetDescriptor()->full_name(), type_url_prefix), arena);
-  return message.SerializeToString(
-      value_->Mutable(ArenaStringPtr::EmptyDefault{}, arena));
+  return message.SerializeToString(value_->Mutable(arena));
 }
 
 bool AnyMetadata::UnpackTo(Message* message) const {

src/google/protobuf/any.pb.cc

@@ -119,18 +119,18 @@ Any::Any(const Any& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   type_url_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    type_url_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_type_url().empty()) {
-    type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_type_url(), 
+    type_url_.Set(from._internal_type_url(), 
       GetArenaForAllocation());
   }
   value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_value().empty()) {
-    value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_value(), 
+    value_.Set(from._internal_value(), 
       GetArenaForAllocation());
   }
   // @@protoc_insertion_point(copy_constructor:google.protobuf.Any)
@@ -139,11 +139,11 @@ Any::Any(const Any& from)
 inline void Any::SharedCtor() {
 type_url_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  type_url_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 }
 
@@ -158,8 +158,8 @@ Any::~Any() {
 
 inline void Any::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  type_url_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  type_url_.Destroy();
+  value_.Destroy();
 }
 
 void Any::SetCachedSize(int size) const {
@@ -325,12 +325,10 @@ void Any::InternalSwap(Any* other) {
   auto* rhs_arena = other->GetArenaForAllocation();
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &type_url_, lhs_arena,
       &other->type_url_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &value_, lhs_arena,
       &other->value_, rhs_arena
   );

src/google/protobuf/any.pb.h

@@ -275,7 +275,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Any::set_type_url(ArgT0&& arg0, ArgT... args) {
  
- type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ type_url_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Any.type_url)
 }
 inline std::string* Any::mutable_type_url() {
@@ -288,15 +288,15 @@ inline const std::string& Any::_internal_type_url() const {
 }
 inline void Any::_internal_set_type_url(const std::string& value) {
   
-  type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  type_url_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Any::_internal_mutable_type_url() {
   
-  return type_url_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return type_url_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Any::release_type_url() {
   // @@protoc_insertion_point(field_release:google.protobuf.Any.type_url)
-  return type_url_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return type_url_.Release();
 }
 inline void Any::set_allocated_type_url(std::string* type_url) {
   if (type_url != nullptr) {
@@ -304,11 +304,10 @@ inline void Any::set_allocated_type_url(std::string* type_url) {
   } else {
     
   }
-  type_url_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), type_url,
-      GetArenaForAllocation());
+  type_url_.SetAllocated(type_url, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (type_url_.IsDefault()) {
-    type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    type_url_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Any.type_url)
@@ -326,7 +325,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Any::set_value(ArgT0&& arg0, ArgT... args) {
  
- value_.SetBytes(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ value_.SetBytes(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Any.value)
 }
 inline std::string* Any::mutable_value() {
@@ -339,15 +338,15 @@ inline const std::string& Any::_internal_value() const {
 }
 inline void Any::_internal_set_value(const std::string& value) {
   
-  value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  value_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Any::_internal_mutable_value() {
   
-  return value_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return value_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Any::release_value() {
   // @@protoc_insertion_point(field_release:google.protobuf.Any.value)
-  return value_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return value_.Release();
 }
 inline void Any::set_allocated_value(std::string* value) {
   if (value != nullptr) {
@@ -355,11 +354,10 @@ inline void Any::set_allocated_value(std::string* value) {
   } else {
     
   }
-  value_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), value,
-      GetArenaForAllocation());
+  value_.SetAllocated(value, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (value_.IsDefault()) {
-    value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    value_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Any.value)

src/google/protobuf/any_lite.cc

@@ -55,10 +55,8 @@ const char kTypeGoogleProdComPrefix[] = "type.googleprod.com/";
 bool AnyMetadata::InternalPackFrom(Arena* arena, const MessageLite& message,
                                    StringPiece type_url_prefix,
                                    StringPiece type_name) {
-  type_url_->Set(&::google::protobuf::internal::GetEmptyString(),
-                 GetTypeUrl(type_name, type_url_prefix), arena);
-  return message.SerializeToString(
-      value_->Mutable(ArenaStringPtr::EmptyDefault{}, arena));
+  type_url_->Set(GetTypeUrl(type_name, type_url_prefix), arena);
+  return message.SerializeToString(value_->Mutable(arena));
 }
 
 bool AnyMetadata::InternalUnpackTo(StringPiece type_name,

src/google/protobuf/api.pb.cc

@@ -204,18 +204,18 @@ Api::Api(const Api& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   version_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    version_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    version_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_version().empty()) {
-    version_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_version(), 
+    version_.Set(from._internal_version(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_source_context()) {
@@ -230,11 +230,11 @@ Api::Api(const Api& from)
 inline void Api::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 version_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  version_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  version_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&source_context_) - reinterpret_cast<char*>(this)),
@@ -253,8 +253,8 @@ Api::~Api() {
 
 inline void Api::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  version_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  version_.Destroy();
   if (this != internal_default_instance()) delete source_context_;
 }
 
@@ -574,12 +574,10 @@ void Api::InternalSwap(Api* other) {
   options_.InternalSwap(&other->options_);
   mixins_.InternalSwap(&other->mixins_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &version_, lhs_arena,
       &other->version_, rhs_arena
   );
@@ -619,26 +617,26 @@ Method::Method(const Method& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   request_type_url_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    request_type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    request_type_url_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_request_type_url().empty()) {
-    request_type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_request_type_url(), 
+    request_type_url_.Set(from._internal_request_type_url(), 
       GetArenaForAllocation());
   }
   response_type_url_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    response_type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    response_type_url_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_response_type_url().empty()) {
-    response_type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_response_type_url(), 
+    response_type_url_.Set(from._internal_response_type_url(), 
       GetArenaForAllocation());
   }
   ::memcpy(&request_streaming_, &from.request_streaming_,
@@ -650,15 +648,15 @@ Method::Method(const Method& from)
 inline void Method::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 request_type_url_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  request_type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  request_type_url_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 response_type_url_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  response_type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  response_type_url_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&request_streaming_) - reinterpret_cast<char*>(this)),
@@ -677,9 +675,9 @@ Method::~Method() {
 
 inline void Method::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  request_type_url_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  response_type_url_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  request_type_url_.Destroy();
+  response_type_url_.Destroy();
 }
 
 void Method::SetCachedSize(int size) const {
@@ -984,17 +982,14 @@ void Method::InternalSwap(Method* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   options_.InternalSwap(&other->options_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &request_type_url_, lhs_arena,
       &other->request_type_url_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &response_type_url_, lhs_arena,
       &other->response_type_url_, rhs_arena
   );
@@ -1029,18 +1024,18 @@ Mixin::Mixin(const Mixin& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   root_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    root_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    root_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_root().empty()) {
-    root_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_root(), 
+    root_.Set(from._internal_root(), 
       GetArenaForAllocation());
   }
   // @@protoc_insertion_point(copy_constructor:google.protobuf.Mixin)
@@ -1049,11 +1044,11 @@ Mixin::Mixin(const Mixin& from)
 inline void Mixin::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 root_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  root_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  root_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 }
 
@@ -1068,8 +1063,8 @@ Mixin::~Mixin() {
 
 inline void Mixin::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  root_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  root_.Destroy();
 }
 
 void Mixin::SetCachedSize(int size) const {
@@ -1240,12 +1235,10 @@ void Mixin::InternalSwap(Mixin* other) {
   auto* rhs_arena = other->GetArenaForAllocation();
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &root_, lhs_arena,
       &other->root_, rhs_arena
   );

src/google/protobuf/api.pb.h

@@ -739,7 +739,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Api::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Api.name)
 }
 inline std::string* Api::mutable_name() {
@@ -752,15 +752,15 @@ inline const std::string& Api::_internal_name() const {
 }
 inline void Api::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Api::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Api::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Api.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void Api::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -768,11 +768,10 @@ inline void Api::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Api.name)
@@ -867,7 +866,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Api::set_version(ArgT0&& arg0, ArgT... args) {
  
- version_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ version_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Api.version)
 }
 inline std::string* Api::mutable_version() {
@@ -880,15 +879,15 @@ inline const std::string& Api::_internal_version() const {
 }
 inline void Api::_internal_set_version(const std::string& value) {
   
-  version_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  version_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Api::_internal_mutable_version() {
   
-  return version_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return version_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Api::release_version() {
   // @@protoc_insertion_point(field_release:google.protobuf.Api.version)
-  return version_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return version_.Release();
 }
 inline void Api::set_allocated_version(std::string* version) {
   if (version != nullptr) {
@@ -896,11 +895,10 @@ inline void Api::set_allocated_version(std::string* version) {
   } else {
     
   }
-  version_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), version,
-      GetArenaForAllocation());
+  version_.SetAllocated(version, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (version_.IsDefault()) {
-    version_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    version_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Api.version)
@@ -977,8 +975,7 @@ inline void Api::set_allocated_source_context(::PROTOBUF_NAMESPACE_ID::SourceCon
   }
   if (source_context) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-        ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<
-            ::PROTOBUF_NAMESPACE_ID::MessageLite>::GetOwningArena(
+        ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(
                 reinterpret_cast<::PROTOBUF_NAMESPACE_ID::MessageLite*>(source_context));
     if (message_arena != submessage_arena) {
       source_context = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(
@@ -1068,7 +1065,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Method::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Method.name)
 }
 inline std::string* Method::mutable_name() {
@@ -1081,15 +1078,15 @@ inline const std::string& Method::_internal_name() const {
 }
 inline void Method::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Method::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Method::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Method.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void Method::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -1097,11 +1094,10 @@ inline void Method::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Method.name)
@@ -1119,7 +1115,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Method::set_request_type_url(ArgT0&& arg0, ArgT... args) {
  
- request_type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ request_type_url_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Method.request_type_url)
 }
 inline std::string* Method::mutable_request_type_url() {
@@ -1132,15 +1128,15 @@ inline const std::string& Method::_internal_request_type_url() const {
 }
 inline void Method::_internal_set_request_type_url(const std::string& value) {
   
-  request_type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  request_type_url_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Method::_internal_mutable_request_type_url() {
   
-  return request_type_url_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return request_type_url_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Method::release_request_type_url() {
   // @@protoc_insertion_point(field_release:google.protobuf.Method.request_type_url)
-  return request_type_url_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return request_type_url_.Release();
 }
 inline void Method::set_allocated_request_type_url(std::string* request_type_url) {
   if (request_type_url != nullptr) {
@@ -1148,11 +1144,10 @@ inline void Method::set_allocated_request_type_url(std::string* request_type_url
   } else {
     
   }
-  request_type_url_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), request_type_url,
-      GetArenaForAllocation());
+  request_type_url_.SetAllocated(request_type_url, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (request_type_url_.IsDefault()) {
-    request_type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    request_type_url_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Method.request_type_url)
@@ -1190,7 +1185,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Method::set_response_type_url(ArgT0&& arg0, ArgT... args) {
  
- response_type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ response_type_url_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Method.response_type_url)
 }
 inline std::string* Method::mutable_response_type_url() {
@@ -1203,15 +1198,15 @@ inline const std::string& Method::_internal_response_type_url() const {
 }
 inline void Method::_internal_set_response_type_url(const std::string& value) {
   
-  response_type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  response_type_url_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Method::_internal_mutable_response_type_url() {
   
-  return response_type_url_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return response_type_url_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Method::release_response_type_url() {
   // @@protoc_insertion_point(field_release:google.protobuf.Method.response_type_url)
-  return response_type_url_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return response_type_url_.Release();
 }
 inline void Method::set_allocated_response_type_url(std::string* response_type_url) {
   if (response_type_url != nullptr) {
@@ -1219,11 +1214,10 @@ inline void Method::set_allocated_response_type_url(std::string* response_type_u
   } else {
     
   }
-  response_type_url_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), response_type_url,
-      GetArenaForAllocation());
+  response_type_url_.SetAllocated(response_type_url, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (response_type_url_.IsDefault()) {
-    response_type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    response_type_url_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Method.response_type_url)
@@ -1322,7 +1316,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Mixin::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Mixin.name)
 }
 inline std::string* Mixin::mutable_name() {
@@ -1335,15 +1329,15 @@ inline const std::string& Mixin::_internal_name() const {
 }
 inline void Mixin::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Mixin::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Mixin::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Mixin.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void Mixin::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -1351,11 +1345,10 @@ inline void Mixin::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Mixin.name)
@@ -1373,7 +1366,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Mixin::set_root(ArgT0&& arg0, ArgT... args) {
  
- root_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ root_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Mixin.root)
 }
 inline std::string* Mixin::mutable_root() {
@@ -1386,15 +1379,15 @@ inline const std::string& Mixin::_internal_root() const {
 }
 inline void Mixin::_internal_set_root(const std::string& value) {
   
-  root_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  root_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Mixin::_internal_mutable_root() {
   
-  return root_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return root_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Mixin::release_root() {
   // @@protoc_insertion_point(field_release:google.protobuf.Mixin.root)
-  return root_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return root_.Release();
 }
 inline void Mixin::set_allocated_root(std::string* root) {
   if (root != nullptr) {
@@ -1402,11 +1395,10 @@ inline void Mixin::set_allocated_root(std::string* root) {
   } else {
     
   }
-  root_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), root,
-      GetArenaForAllocation());
+  root_.SetAllocated(root, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (root_.IsDefault()) {
-    root_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    root_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Mixin.root)

src/google/protobuf/arena.h

@@ -410,27 +410,10 @@ class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
 
   template <typename T>
   class InternalHelper {
-   public:
+   private:
     // Provides access to protected GetOwningArena to generated messages.
     static Arena* GetOwningArena(const T* p) { return p->GetOwningArena(); }
 
-    // Provides access to protected GetArenaForAllocation to generated messages.
-    static Arena* GetArenaForAllocation(const T* p) {
-      return GetArenaForAllocationInternal(
-          p, std::is_convertible<T*, MessageLite*>());
-    }
-
-    // Creates message-owned arena.
-    static Arena* CreateMessageOwnedArena() {
-      return new Arena(internal::MessageOwned{});
-    }
-
-    // Checks whether the given arena is message-owned.
-    static bool IsMessageOwnedArena(Arena* arena) {
-      return arena->IsMessageOwned();
-    }
-
-   private:
     static Arena* GetArenaForAllocationInternal(
         const T* p, std::true_type /*is_derived_from<MessageLite>*/) {
       return p->GetArenaForAllocation();
@@ -513,6 +496,29 @@ class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
     friend class TestUtil::ReflectionTester;
   };
 
+  // Provides access to protected GetOwningArena to generated messages.  For
+  // internal use only.
+  template <typename T>
+  static Arena* InternalGetOwningArena(const T* p) {
+    return InternalHelper<T>::GetOwningArena(p);
+  }
+
+  // Provides access to protected GetArenaForAllocation to generated messages.
+  // For internal use only.
+  template <typename T>
+  static Arena* InternalGetArenaForAllocation(const T* p) {
+    return InternalHelper<T>::GetArenaForAllocationInternal(
+        p, std::is_convertible<T*, MessageLite*>());
+  }
+
+  // Creates message-owned arena.  For internal use only.
+  static Arena* InternalCreateMessageOwnedArena() {
+    return new Arena(internal::MessageOwned{});
+  }
+
+  // Checks whether this arena is message-owned.  For internal use only.
+  bool InternalIsMessageOwnedArena() { return IsMessageOwned(); }
+
   // Helper typetraits that indicates support for arenas in a type T at compile
   // time. This is public only to allow construction of higher-level templated
   // utilities.

src/google/protobuf/arena_unittest.cc

@@ -547,13 +547,11 @@ TEST(ArenaTest, UnsafeArenaSwap) {
 TEST(ArenaTest, GetOwningArena) {
   Arena arena;
   auto* m1 = Arena::CreateMessage<TestAllTypes>(&arena);
-  EXPECT_EQ(Arena::InternalHelper<TestAllTypes>::GetOwningArena(m1), &arena);
-  EXPECT_EQ(
-      &arena,
-      Arena::InternalHelper<RepeatedPtrField<ForeignMessage>>::GetOwningArena(
-          m1->mutable_repeated_foreign_message()));
-  EXPECT_EQ(&arena, Arena::InternalHelper<RepeatedField<int>>::GetOwningArena(
-                        m1->mutable_repeated_int32()));
+  EXPECT_EQ(Arena::InternalGetOwningArena(m1), &arena);
+  EXPECT_EQ(&arena, Arena::InternalGetOwningArena(
+                        m1->mutable_repeated_foreign_message()));
+  EXPECT_EQ(&arena,
+            Arena::InternalGetOwningArena(m1->mutable_repeated_int32()));
 }
 
 TEST(ArenaTest, SwapBetweenArenasUsingReflection) {

src/google/protobuf/arenastring.cc

@@ -112,13 +112,7 @@ std::string* ArenaStringPtr::SetAndReturnNewString() {
   return new_string;
 }
 
-void ArenaStringPtr::DestroyNoArenaSlowPath() {
-  GOOGLE_DCHECK(tagged_ptr_.IsAllocated());
-  delete UnsafeMutablePointer();
-}
-
-void ArenaStringPtr::Set(const std::string*, ConstStringParam value,
-                         ::google::protobuf::Arena* arena) {
+void ArenaStringPtr::Set(ConstStringParam value, Arena* arena) {
   if (IsDefault()) {
     // If we're not on an arena, skip straight to a true string to avoid
     // possible copy cost later.
@@ -128,8 +122,8 @@ void ArenaStringPtr::Set(const std::string*, ConstStringParam value,
     UnsafeMutablePointer()->assign(value.data(), value.length());
   }
 }
-void ArenaStringPtr::Set(const std::string*, std::string&& value,
-                         ::google::protobuf::Arena* arena) {
+
+void ArenaStringPtr::Set(std::string&& value, Arena* arena) {
   if (IsDefault()) {
     NewString(arena, std::move(value));
   } else if (IsFixedSizeArena()) {
@@ -142,47 +136,26 @@ void ArenaStringPtr::Set(const std::string*, std::string&& value,
   }
 }
 
-void ArenaStringPtr::Set(EmptyDefault, ConstStringParam value,
-                         ::google::protobuf::Arena* arena) {
-  Set(&GetEmptyStringAlreadyInited(), value, arena);
-}
-
-void ArenaStringPtr::Set(EmptyDefault, std::string&& value,
-                         ::google::protobuf::Arena* arena) {
-  Set(&GetEmptyStringAlreadyInited(), std::move(value), arena);
-}
-
-void ArenaStringPtr::Set(NonEmptyDefault, ConstStringParam value,
-                         ::google::protobuf::Arena* arena) {
-  Set(nullptr, value, arena);
-}
-
-void ArenaStringPtr::Set(NonEmptyDefault, std::string&& value,
-                         ::google::protobuf::Arena* arena) {
-  Set(nullptr, std::move(value), arena);
-}
-
-std::string* ArenaStringPtr::Mutable(EmptyDefault, ::google::protobuf::Arena* arena) {
-  if (!IsFixedSizeArena() && !IsDefault()) {
-    return UnsafeMutablePointer();
+std::string* ArenaStringPtr::Mutable(Arena* arena) {
+  if (tagged_ptr_.IsMutable()) {
+    return tagged_ptr_.Get();
   } else {
     return MutableSlow(arena);
   }
 }
 
 std::string* ArenaStringPtr::Mutable(const LazyString& default_value,
-                                     ::google::protobuf::Arena* arena) {
-  if (!IsFixedSizeArena() && !IsDefault()) {
-    return UnsafeMutablePointer();
+                                     Arena* arena) {
+  if (tagged_ptr_.IsMutable()) {
+    return tagged_ptr_.Get();
   } else {
     return MutableSlow(arena, default_value);
   }
 }
 
-std::string* ArenaStringPtr::MutableNoCopy(const std::string*,
-                                           ::google::protobuf::Arena* arena) {
-  if (!IsFixedSizeArena() && !IsDefault()) {
-    return UnsafeMutablePointer();
+std::string* ArenaStringPtr::MutableNoCopy(Arena* arena) {
+  if (tagged_ptr_.IsMutable()) {
+    return tagged_ptr_.Get();
   } else {
     GOOGLE_DCHECK(IsDefault());
     // Allocate empty. The contents are not relevant.
@@ -197,45 +170,24 @@ std::string* ArenaStringPtr::MutableSlow(::google::protobuf::Arena* arena,
   return NewString(arena, lazy_default.get()...);
 }
 
-std::string* ArenaStringPtr::Release(const std::string* default_value,
-                                     ::google::protobuf::Arena* arena) {
-  if (IsDefault()) {
-    return nullptr;
-  } else {
-    return ReleaseNonDefault(default_value, arena);
-  }
-}
+std::string* ArenaStringPtr::Release() {
+  if (IsDefault()) return nullptr;
 
-std::string* ArenaStringPtr::ReleaseNonDefault(const std::string* default_value,
-                                               ::google::protobuf::Arena* arena) {
-  GOOGLE_DCHECK(!IsDefault());
-
-  if (!IsFixedSizeArena()) {
-    std::string* released;
-    if (arena != nullptr) {
-      released = new std::string;
-      released->swap(*UnsafeMutablePointer());
-    } else {
-      released = UnsafeMutablePointer();
-    }
-    tagged_ptr_.SetDefault(default_value);
-    return released;
-  } else /* IsFixedSizeArena() */ {
-    GOOGLE_DCHECK(arena != nullptr);
-    std::string* released = new std::string(Get());
-    tagged_ptr_.SetDefault(default_value);
-    return released;
+  std::string* released = tagged_ptr_.Get();
+  if (!tagged_ptr_.IsAllocated()) {
+    released = tagged_ptr_.IsMutable() ? new std::string(std::move(*released))
+                                       : new std::string(*released);
   }
+  InitDefault();
+  return released;
 }
 
-void ArenaStringPtr::SetAllocated(const std::string* default_value,
-                                  std::string* value, ::google::protobuf::Arena* arena) {
+void ArenaStringPtr::SetAllocated(std::string* value, Arena* arena) {
   // Release what we have first.
-  if (arena == nullptr && !IsDefault()) {
-    delete UnsafeMutablePointer();
-  }
+  Destroy();
+
   if (value == nullptr) {
-    tagged_ptr_.SetDefault(default_value);
+    InitDefault();
   } else {
 #ifndef NDEBUG
     // On debug builds, copy the string so the address differs.  delete will
@@ -249,23 +201,12 @@ void ArenaStringPtr::SetAllocated(const std::string* default_value,
   }
 }
 
-void ArenaStringPtr::Destroy(const std::string*, ::google::protobuf::Arena* arena) {
-  if (arena == nullptr) {
-    GOOGLE_DCHECK(!IsFixedSizeArena());
-    if (!IsDefault()) {
-      delete UnsafeMutablePointer();
-    }
+void ArenaStringPtr::Destroy() {
+  if (tagged_ptr_.IsAllocated()) {
+    delete tagged_ptr_.Get();
   }
 }
 
-void ArenaStringPtr::Destroy(EmptyDefault, ::google::protobuf::Arena* arena) {
-  Destroy(&GetEmptyStringAlreadyInited(), arena);
-}
-
-void ArenaStringPtr::Destroy(NonEmptyDefault, ::google::protobuf::Arena* arena) {
-  Destroy(nullptr, arena);
-}
-
 void ArenaStringPtr::ClearToEmpty() {
   if (IsDefault()) {
     // Already set to default -- do nothing.

src/google/protobuf/arenastring.h

@@ -187,7 +187,7 @@ class TaggedPtr {
   }
 
   inline T* TagAs(Type type, T* p) {
-    GOOGLE_DCHECK(type == kDefault || p != nullptr);
+    GOOGLE_DCHECK(p != nullptr);
     assert_aligned(p);
     ptr_ = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(p) | type);
     return p;
@@ -232,84 +232,84 @@ struct PROTOBUF_EXPORT ArenaStringPtr {
   struct EmptyDefault {};
   struct NonEmptyDefault {};
 
-  void Set(const std::string* default_value, ConstStringParam value,
-           ::google::protobuf::Arena* arena);
-  void Set(const std::string* default_value, std::string&& value,
-           ::google::protobuf::Arena* arena);
-  void Set(EmptyDefault, ConstStringParam value, ::google::protobuf::Arena* arena);
-  void Set(EmptyDefault, std::string&& value, ::google::protobuf::Arena* arena);
-  void Set(NonEmptyDefault, ConstStringParam value, ::google::protobuf::Arena* arena);
-  void Set(NonEmptyDefault, std::string&& value, ::google::protobuf::Arena* arena);
-  template <typename FirstParam>
-  void Set(FirstParam p1, const char* str, ::google::protobuf::Arena* arena) {
-    Set(p1, ConstStringParam(str), arena);
-  }
-  template <typename FirstParam>
-  void Set(FirstParam p1, const char* str, size_t size,
-           ::google::protobuf::Arena* arena) {
-    ConstStringParam sp{str, size};  // for string_view and `const string &`
-    Set(p1, sp, arena);
-  }
-  template <typename FirstParam, typename RefWrappedType>
-  void Set(FirstParam p1,
-           std::reference_wrapper<RefWrappedType> const_string_ref,
+  // Called from generated code / reflection runtime only. Resets value to point
+  // to a default string pointer, with the semantics that this ArenaStringPtr
+  // does not own the pointed-to memory. Disregards initial value of ptr_ (so
+  // this is the *ONLY* safe method to call after construction or when
+  // reinitializing after becoming the active field in a oneof union).
+  inline void InitDefault();
+
+  // Similar to `InitDefault` except that it allows the default value to be
+  // initialized to an externally owned string. This method is called from
+  // parsing code. `str` must not be null and outlive this instance.
+  inline void InitExternal(const std::string* str);
+
+  // Called from generated code / reflection runtime only. Resets the value of
+  // this instances to the heap allocated value in `str`. `str` must not be
+  // null. Invokes `arena->Own(str)` to transfer ownership into the arena if
+  // `arena` is not null, else, `str` will be owned by ArenaStringPtr. This
+  // function should only be used to initialize a ArenaStringPtr or on an
+  // instance known to not carry any heap allocated value.
+  inline void InitAllocated(std::string* str, Arena* arena);
+
+  void Set(ConstStringParam value, Arena* arena);
+  void Set(std::string&& value, Arena* arena);
+  void Set(const char* s, Arena* arena);
+  void Set(const char* s, size_t n, Arena* arena);
+
+  void SetBytes(ConstStringParam value, Arena* arena);
+  void SetBytes(std::string&& value, Arena* arena);
+  void SetBytes(const char* s, Arena* arena);
+  void SetBytes(const void* p, size_t n, Arena* arena);
+
+  template <typename RefWrappedType>
+  void Set(std::reference_wrapper<RefWrappedType> const_string_ref,
            ::google::protobuf::Arena* arena) {
-    Set(p1, const_string_ref.get(), arena);
+    Set(const_string_ref.get(), arena);
   }
 
-  template <typename FirstParam, typename SecondParam>
-  void SetBytes(FirstParam p1, SecondParam&& p2, ::google::protobuf::Arena* arena) {
-    Set(p1, static_cast<SecondParam&&>(p2), arena);
-  }
-  template <typename FirstParam>
-  void SetBytes(FirstParam p1, const void* str, size_t size,
-                ::google::protobuf::Arena* arena) {
-    // must work whether ConstStringParam is string_view or `const string &`
-    ConstStringParam sp{static_cast<const char*>(str), size};
-    Set(p1, sp, arena);
-  }
+  // Returns a mutable std::string reference.
+  // The version accepting a `LazyString` value is used in the generated code to
+  // initialize mutable copies for fields with a non-empty default where the
+  // default value is lazily initialized.
+  std::string* Mutable(Arena* arena);
+  std::string* Mutable(const LazyString& default_value, Arena* arena);
+
+  // Gets a mutable pointer with unspecified contents.
+  // This function is identical to Mutable(), except it is optimized for the
+  // case where the caller is not interested in the current contents. For
+  // example, if the current field is not mutable, it will re-initialize the
+  // value with an empty string rather than a (non-empty) default value.
+  // Likewise, if the current value is a fixed size arena string with contents,
+  // it will be initialized into an empty mutable arena string.
+  std::string* MutableNoCopy(Arena* arena);
 
   // Basic accessors.
   PROTOBUF_NDEBUG_INLINE const std::string& Get() const {
     // Unconditionally mask away the tag.
     return *tagged_ptr_.Get();
   }
-  PROTOBUF_NDEBUG_INLINE const std::string* GetPointer() const {
-    // Unconditionally mask away the tag.
+
+  // Returns a pointer to the stored contents for this instance.
+  // This method is for internal debugging and tracking purposes only.
+  PROTOBUF_NDEBUG_INLINE const std::string* UnsafeGetPointer() const
+      PROTOBUF_RETURNS_NONNULL {
     return tagged_ptr_.Get();
   }
 
-  // For fields with an empty default value.
-  std::string* Mutable(EmptyDefault, ::google::protobuf::Arena* arena);
-  // For fields with a non-empty default value.
-  std::string* Mutable(const LazyString& default_value, ::google::protobuf::Arena* arena);
-
   // Release returns a std::string* instance that is heap-allocated and is not
   // Own()'d by any arena. If the field is not set, this returns nullptr. The
-  // caller retains ownership. Clears this field back to nullptr state. Used to
-  // implement release_<field>() methods on generated classes.
-  PROTOBUF_NODISCARD std::string* Release(const std::string* default_value,
-                                          ::google::protobuf::Arena* arena);
-  PROTOBUF_NODISCARD std::string* ReleaseNonDefault(
-      const std::string* default_value, ::google::protobuf::Arena* arena);
+  // caller retains ownership. Clears this field back to the default state.
+  // Used to implement release_<field>() methods on generated classes.
+  PROTOBUF_NODISCARD std::string* Release();
 
   // Takes a std::string that is heap-allocated, and takes ownership. The
   // std::string's destructor is registered with the arena. Used to implement
   // set_allocated_<field> in generated classes.
-  void SetAllocated(const std::string* default_value, std::string* value,
-                    ::google::protobuf::Arena* arena);
-
-  // Swaps internal pointers. Arena-safety semantics: this is guarded by the
-  // logic in Swap()/UnsafeArenaSwap() at the message level, so this method is
-  // 'unsafe' if called directly.
-  inline PROTOBUF_NDEBUG_INLINE static void InternalSwap(
-      const std::string* default_value, ArenaStringPtr* rhs, Arena* rhs_arena,
-      ArenaStringPtr* lhs, Arena* lhs_arena);
+  void SetAllocated(std::string* value, Arena* arena);
 
   // Frees storage (if not on an arena).
-  void Destroy(const std::string* default_value, ::google::protobuf::Arena* arena);
-  void Destroy(EmptyDefault, ::google::protobuf::Arena* arena);
-  void Destroy(NonEmptyDefault, ::google::protobuf::Arena* arena);
+  void Destroy();
 
   // Clears content, but keeps allocated std::string, to avoid the overhead of
   // heap operations. After this returns, the content (as seen by the user) will
@@ -326,37 +326,109 @@ struct PROTOBUF_EXPORT ArenaStringPtr {
   // (as seen by the user) will always be equal to |default_value|.
   void ClearToDefault(const LazyString& default_value, ::google::protobuf::Arena* arena);
 
-  // Called from generated code / reflection runtime only. Resets value to point
-  // to a default string pointer, with the semantics that this ArenaStringPtr
-  // does not own the pointed-to memory. Disregards initial value of ptr_ (so
-  // this is the *ONLY* safe method to call after construction or when
-  // reinitializing after becoming the active field in a oneof union).
-  // This function allows an explicit default value other than the default
-  // global empty string. This is used in unit tests and by fields with
-  // explicit non-empty default string values using null defaults.
-  inline void InitDefault();
-  inline void InitDefault(const std::string* str);
+  // Swaps internal pointers. Arena-safety semantics: this is guarded by the
+  // logic in Swap()/UnsafeArenaSwap() at the message level, so this method is
+  // 'unsafe' if called directly.
+  inline PROTOBUF_NDEBUG_INLINE static void InternalSwap(ArenaStringPtr* rhs,
+                                                         Arena* rhs_arena,
+                                                         ArenaStringPtr* lhs,
+                                                         Arena* lhs_arena);
+
+  // --------------------------------------------------------
+  // Below functions will be removed in subsequent code change
+  // --------------------------------------------------------
+#ifdef DEPRECATED_METHODS_TO_BE_DELETED
+  PROTOBUF_NDEBUG_INLINE const std::string* GetPointer() const {
+    return UnsafeGetPointer();
+  }
 
-  // Called from generated code / reflection runtime only. Resets the value of
-  // this instances to the heap allocated value in `str`. `str` must not be
-  // null. Invokes `arena->Own(str)` to transfer ownership into the arena if
-  // `arena` is not null, else, `str` will be owned by ArenaStringPtr. This
-  // function should only be used to initialize a ArenaStringPtr or on an
-  // instance known to not carry any heap allocated value.
-  inline void InitAllocated(std::string* str, Arena* arena);
+  template <typename DefaultArg>
+  void Set(DefaultArg, ConstStringParam value, Arena* arena) {
+    return Set(value, arena);
+  }
+  template <typename DefaultArg>
+  void Set(DefaultArg, std::string&& value, Arena* arena) {
+    return Set(std::move(value), arena);
+  }
+  template <typename DefaultArg>
+  void Set(DefaultArg, const char* s, Arena* arena) {
+    return Set(ConstStringParam{s}, arena);
+  }
+  template <typename DefaultArg>
+  void Set(DefaultArg, const char* s, size_t n, Arena* arena) {
+    return Set(ConstStringParam{s, n}, arena);
+  }
 
-  // Returns a mutable pointer, but doesn't initialize the string to the
-  // default value.
-  std::string* MutableNoArenaNoDefault(const std::string* default_value);
+  void SetBytes(EmptyDefault, ConstStringParam value, Arena* arena) {
+    return Set(value, arena);
+  }
+  void SetBytes(NonEmptyDefault, ConstStringParam value, Arena* arena) {
+    return Set(value, arena);
+  }
+  void SetBytes(const std::string*, ConstStringParam value, Arena* arena) {
+    return Set(value, arena);
+  }
+  void SetBytes(EmptyDefault, std::string&& value, Arena* arena) {
+    return Set(std::move(value), arena);
+  }
+  void SetBytes(NonEmptyDefault, std::string&& value, Arena* arena) {
+    return Set(std::move(value), arena);
+  }
+  void SetBytes(const std::string*, std::string&& value, Arena* arena) {
+    return Set(std::move(value), arena);
+  }
+  void SetBytes(EmptyDefault, const char* s, Arena* arena) {
+    return Set(s, arena);
+  }
+  void SetBytes(NonEmptyDefault, const char* s, Arena* arena) {
+    return Set(s, arena);
+  }
+  void SetBytes(const std::string*, const char* s, Arena* arena) {
+    return Set(s, arena);
+  }
+  void SetBytes(EmptyDefault, const void* p, size_t n, Arena* arena) {
+    return SetBytes(p, n, arena);
+  }
+  void SetBytes(NonEmptyDefault, const void* p, size_t n, Arena* arena) {
+    return SetBytes(p, n, arena);
+  }
+  void SetBytes(const std::string*, const void* p, size_t n, Arena* arena) {
+    return SetBytes(p, n, arena);
+  }
+
+  std::string* Mutable(EmptyDefault, Arena* arena) { return Mutable(arena); }
+  std::string* MutableNoArenaNoDefault(const std::string*) {
+    return Mutable(nullptr);
+  }
+  std::string* MutableNoCopy(const std::string*, ::google::protobuf::Arena* arena) {
+    return MutableNoCopy(arena);
+  }
+
+  PROTOBUF_NODISCARD std::string* Release(const std::string*, Arena* arena) {
+    return Release();
+  }
+  PROTOBUF_NODISCARD std::string* ReleaseNonDefault(const std::string*,
+                                                    Arena* arena) {
+    return Release();
+  }
 
-  // Get a mutable pointer with unspecified contents.
-  // Similar to `MutableNoArenaNoDefault`, but also handles the arena case.
-  // If the value was donated, the contents are discarded.
-  std::string* MutableNoCopy(const std::string* default_value,
-                             ::google::protobuf::Arena* arena);
+  void SetAllocated(const std::string*, std::string* value, Arena* arena) {
+    SetAllocated(value, arena);
+  }
 
-  // Destroy the string. Assumes `arena == nullptr`.
-  void DestroyNoArena(const std::string* default_value);
+  void Destroy(const std::string*, ::google::protobuf::Arena* arena) { Destroy(); }
+  void Destroy(EmptyDefault, ::google::protobuf::Arena* arena) { Destroy(); }
+  void Destroy(NonEmptyDefault, ::google::protobuf::Arena* arena) { Destroy(); }
+  void DestroyNoArena(const std::string*) { Destroy(); }
+
+  inline PROTOBUF_NDEBUG_INLINE static void InternalSwap(const std::string*,
+                                                         ArenaStringPtr* rhs,
+                                                         Arena* rhs_arena,
+                                                         ArenaStringPtr* lhs,
+                                                         Arena* lhs_arena) {
+    InternalSwap(rhs, rhs_arena, lhs, lhs_arena);
+  }
+#endif  // DEPRECATED_METHODS_TO_BE_DELETED
 
   // Internal setter used only at parse time to directly set a donated string
   // value.
@@ -407,9 +479,6 @@ struct PROTOBUF_EXPORT ArenaStringPtr {
   // Sets value to a newly allocated string and returns it
   std::string* SetAndReturnNewString();
 
-  // Destroys the non-default string value out-of-line
-  void DestroyNoArenaSlowPath();
-
   friend class EpsCopyInputStream;
 };
 
@@ -417,7 +486,7 @@ inline void ArenaStringPtr::InitDefault() {
   tagged_ptr_ = TaggedPtr<std::string>(&fixed_address_empty_string);
 }
 
-inline void ArenaStringPtr::InitDefault(const std::string* str) {
+inline void ArenaStringPtr::InitExternal(const std::string* str) {
   tagged_ptr_.SetDefault(str);
 }
 
@@ -430,9 +499,32 @@ inline void ArenaStringPtr::InitAllocated(std::string* str, Arena* arena) {
   }
 }
 
+inline void ArenaStringPtr::Set(const char* s, Arena* arena) {
+  Set(ConstStringParam{s}, arena);
+}
+
+inline void ArenaStringPtr::Set(const char* s, size_t n, Arena* arena) {
+  Set(ConstStringParam{s, n}, arena);
+}
+
+inline void ArenaStringPtr::SetBytes(ConstStringParam value, Arena* arena) {
+  Set(value, arena);
+}
+
+inline void ArenaStringPtr::SetBytes(std::string&& value, Arena* arena) {
+  Set(std::move(value), arena);
+}
+
+inline void ArenaStringPtr::SetBytes(const char* s, Arena* arena) {
+  Set(s, arena);
+}
+
+inline void ArenaStringPtr::SetBytes(const void* p, size_t n, Arena* arena) {
+  Set(ConstStringParam{static_cast<const char*>(p), n}, arena);
+}
+
 // Make sure rhs_arena allocated rhs, and lhs_arena allocated lhs.
 inline PROTOBUF_NDEBUG_INLINE void ArenaStringPtr::InternalSwap(  //
-    const std::string*,                                           //
     ArenaStringPtr* rhs, Arena* rhs_arena,                        //
     ArenaStringPtr* lhs, Arena* lhs_arena) {
   // Silence unused variable warnings in release buildls.
@@ -466,28 +558,6 @@ inline void ArenaStringPtr::ClearNonDefaultToEmpty() {
   tagged_ptr_.Get()->clear();
 }
 
-inline std::string* ArenaStringPtr::MutableNoArenaNoDefault(
-    const std::string* /* default_value */) {
-  // VERY IMPORTANT for performance and code size: this will reduce to a member
-  // variable load, a pointer check (against |default_value|, in practice a
-  // static global) and a branch to the slowpath (which calls operator new and
-  // the ctor). DO NOT add any tagged-pointer operations here.
-  GOOGLE_DCHECK(!tagged_ptr_.IsArena());
-  if (IsDefault()) {
-    return SetAndReturnNewString();
-  } else {
-    return UnsafeMutablePointer();
-  }
-}
-
-inline void ArenaStringPtr::DestroyNoArena(
-    const std::string* /* default_value */) {
-  GOOGLE_DCHECK(!tagged_ptr_.IsArena());
-  if (!IsDefault()) {
-    DestroyNoArenaSlowPath();
-  }
-}
-
 inline std::string* ArenaStringPtr::UnsafeMutablePointer() {
   GOOGLE_DCHECK(tagged_ptr_.IsMutable());
   GOOGLE_DCHECK(tagged_ptr_.Get() != nullptr);

src/google/protobuf/arenastring_unittest.cc

@@ -34,6 +34,7 @@
 #include <cstdlib>
 #include <memory>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include <google/protobuf/stubs/logging.h>
@@ -72,37 +73,36 @@ INSTANTIATE_TEST_SUITE_P(ArenaString, SingleArena, testing::Bool());
 TEST_P(SingleArena, GetSet) {
   auto arena = GetArena();
   ArenaStringPtr field;
-  field.InitDefault(empty_default);
+  field.InitDefault();
   EXPECT_EQ("", field.Get());
-  field.Set(empty_default, "Test short", arena.get());
+  field.Set("Test short", arena.get());
   EXPECT_EQ("Test short", field.Get());
-  field.Set(empty_default, "Test long long long long value", arena.get());
+  field.Set("Test long long long long value", arena.get());
   EXPECT_EQ("Test long long long long value", field.Get());
-  field.Set(empty_default, "", arena.get());
-  field.Destroy(empty_default, arena.get());
+  field.Set("", arena.get());
+  field.Destroy();
 }
 
 TEST_P(SingleArena, MutableAccessor) {
   auto arena = GetArena();
   ArenaStringPtr field;
-  const std::string* empty_default = &internal::GetEmptyString();
-  field.InitDefault(empty_default);
+  field.InitDefault();
 
-  std::string* mut = field.Mutable(EmptyDefault{}, arena.get());
-  EXPECT_EQ(mut, field.Mutable(EmptyDefault{}, arena.get()));
+  std::string* mut = field.Mutable(arena.get());
+  EXPECT_EQ(mut, field.Mutable(arena.get()));
   EXPECT_EQ(mut, &field.Get());
   EXPECT_NE(empty_default, mut);
   EXPECT_EQ("", *mut);
   *mut = "Test long long long long value";  // ensure string allocates storage
   EXPECT_EQ("Test long long long long value", field.Get());
-  field.Destroy(empty_default, arena.get());
+  field.Destroy();
 }
 
 TEST_P(SingleArena, NullDefault) {
   auto arena = GetArena();
 
   ArenaStringPtr field;
-  field.InitDefault(nullptr);
+  field.InitDefault();
   std::string* mut = field.Mutable(nonempty_default, arena.get());
   EXPECT_EQ(mut, field.Mutable(nonempty_default, arena.get()));
   EXPECT_EQ(mut, &field.Get());
@@ -110,7 +110,7 @@ TEST_P(SingleArena, NullDefault) {
   EXPECT_EQ("default", *mut);
   *mut = "Test long long long long value";  // ensure string allocates storage
   EXPECT_EQ("Test long long long long value", field.Get());
-  field.Destroy(nullptr, arena.get());
+  field.Destroy();
 }
 
 class DualArena : public testing::TestWithParam<std::tuple<bool, bool>> {
@@ -131,23 +131,22 @@ INSTANTIATE_TEST_SUITE_P(ArenaString, DualArena,
 TEST_P(DualArena, Swap) {
   auto lhs_arena = GetLhsArena();
   ArenaStringPtr lhs;
-  lhs.InitDefault(empty_default);
+  lhs.InitDefault();
   ArenaStringPtr rhs;
-  rhs.InitDefault(empty_default);
+  rhs.InitDefault();
 
   {
     auto rhs_arena = GetRhsArena();
-    lhs.Set(empty_default, "lhs value that has some heft", lhs_arena.get());
-    rhs.Set(empty_default, "rhs value that has some heft", rhs_arena.get());
-    ArenaStringPtr::InternalSwap(empty_default,          //
-                                 &lhs, lhs_arena.get(),  //
+    lhs.Set("lhs value that has some heft", lhs_arena.get());
+    rhs.Set("rhs value that has some heft", rhs_arena.get());
+    ArenaStringPtr::InternalSwap(&lhs, lhs_arena.get(),  //
                                  &rhs, rhs_arena.get());
     EXPECT_EQ("rhs value that has some heft", lhs.Get());
     EXPECT_EQ("lhs value that has some heft", rhs.Get());
-    lhs.Destroy(empty_default, rhs_arena.get());
+    lhs.Destroy();
   }
   EXPECT_EQ("lhs value that has some heft", rhs.Get());
-  rhs.Destroy(empty_default, lhs_arena.get());
+  rhs.Destroy();
 }
 
 

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

@@ -91,7 +91,7 @@ void EnumFieldGenerator::GenerateInlineAccessorDefinitions(
   Formatter format(printer, variables_);
   format(
       "inline $type$ $classname$::_internal_$name$() const {\n"
-      "  return static_cast< $type$ >($name$_);\n"
+      "  return static_cast< $type$ >($field$);\n"
       "}\n"
       "inline $type$ $classname$::$name$() const {\n"
       "$annotate_get$"
@@ -104,7 +104,7 @@ void EnumFieldGenerator::GenerateInlineAccessorDefinitions(
   }
   format(
       "  $set_hasbit$\n"
-      "  $name$_ = value;\n"
+      "  $field$ = value;\n"
       "}\n"
       "inline void $classname$::set_$name$($type$ value) {\n"
       "  _internal_set_$name$(value);\n"
@@ -115,7 +115,7 @@ void EnumFieldGenerator::GenerateInlineAccessorDefinitions(
 
 void EnumFieldGenerator::GenerateClearingCode(io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_ = $default$;\n");
+  format("$field$ = $default$;\n");
 }
 
 void EnumFieldGenerator::GenerateMergingCode(io::Printer* printer) const {
@@ -125,7 +125,7 @@ void EnumFieldGenerator::GenerateMergingCode(io::Printer* printer) const {
 
 void EnumFieldGenerator::GenerateSwappingCode(io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("swap($name$_, other->$name$_);\n");
+  format("swap($field$, other->$field$);\n");
 }
 
 void EnumFieldGenerator::GenerateConstructorCode(io::Printer* printer) const {
@@ -177,7 +177,7 @@ void EnumOneofFieldGenerator::GenerateInlineAccessorDefinitions(
   format(
       "inline $type$ $classname$::_internal_$name$() const {\n"
       "  if (_internal_has_$name$()) {\n"
-      "    return static_cast< $type$ >($field_member$);\n"
+      "    return static_cast< $type$ >($field$);\n"
       "  }\n"
       "  return static_cast< $type$ >($default$);\n"
       "}\n"
@@ -195,7 +195,7 @@ void EnumOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "    clear_$oneof_name$();\n"
       "    set_has_$name$();\n"
       "  }\n"
-      "  $field_member$ = value;\n"
+      "  $field$ = value;\n"
       "}\n"
       "inline void $classname$::set_$name$($type$ value) {\n"
       "  _internal_set_$name$(value);\n"
@@ -206,7 +206,7 @@ void EnumOneofFieldGenerator::GenerateInlineAccessorDefinitions(
 
 void EnumOneofFieldGenerator::GenerateClearingCode(io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$field_member$ = $default$;\n");
+  format("$field$ = $default$;\n");
 }
 
 void EnumOneofFieldGenerator::GenerateSwappingCode(io::Printer* printer) const {
@@ -264,7 +264,7 @@ void RepeatedEnumFieldGenerator::GenerateInlineAccessorDefinitions(
   Formatter format(printer, variables_);
   format(
       "inline $type$ $classname$::_internal_$name$(int index) const {\n"
-      "  return static_cast< $type$ >($name$_.Get(index));\n"
+      "  return static_cast< $type$ >($field$.Get(index));\n"
       "}\n"
       "inline $type$ $classname$::$name$(int index) const {\n"
       "$annotate_get$"
@@ -276,7 +276,7 @@ void RepeatedEnumFieldGenerator::GenerateInlineAccessorDefinitions(
     format("  assert($type$_IsValid(value));\n");
   }
   format(
-      "  $name$_.Set(index, value);\n"
+      "  $field$.Set(index, value);\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set:$full_name$)\n"
       "}\n"
@@ -285,7 +285,7 @@ void RepeatedEnumFieldGenerator::GenerateInlineAccessorDefinitions(
     format("  assert($type$_IsValid(value));\n");
   }
   format(
-      "  $name$_.Add(value);\n"
+      "  $field$.Add(value);\n"
       "}\n"
       "inline void $classname$::add_$name$($type$ value) {\n"
       "  _internal_add_$name$(value);\n"
@@ -296,11 +296,11 @@ void RepeatedEnumFieldGenerator::GenerateInlineAccessorDefinitions(
       "$classname$::$name$() const {\n"
       "$annotate_list$"
       "  // @@protoc_insertion_point(field_list:$full_name$)\n"
-      "  return $name$_;\n"
+      "  return $field$;\n"
       "}\n"
       "inline ::$proto_ns$::RepeatedField<int>*\n"
       "$classname$::_internal_mutable_$name$() {\n"
-      "  return &$name$_;\n"
+      "  return &$field$;\n"
       "}\n"
       "inline ::$proto_ns$::RepeatedField<int>*\n"
       "$classname$::mutable_$name$() {\n"
@@ -313,19 +313,19 @@ void RepeatedEnumFieldGenerator::GenerateInlineAccessorDefinitions(
 void RepeatedEnumFieldGenerator::GenerateClearingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.Clear();\n");
+  format("$field$.Clear();\n");
 }
 
 void RepeatedEnumFieldGenerator::GenerateMergingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.MergeFrom(from.$name$_);\n");
+  format("$field$.MergeFrom(from.$field$);\n");
 }
 
 void RepeatedEnumFieldGenerator::GenerateSwappingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.InternalSwap(&other->$name$_);\n");
+  format("$field$.InternalSwap(&other->$field$);\n");
 }
 
 void RepeatedEnumFieldGenerator::GenerateConstructorCode(
@@ -344,7 +344,7 @@ void RepeatedEnumFieldGenerator::GenerateSerializeWithCachedSizesToArray(
         "_$name$_cached_byte_size_.load(std::memory_order_relaxed);\n"
         "  if (byte_size > 0) {\n"
         "    target = stream->WriteEnumPacked(\n"
-        "        $number$, $name$_, byte_size, target);\n"
+        "        $number$, $field$, byte_size, target);\n"
         "  }\n"
         "}\n");
   } else {
@@ -375,7 +375,8 @@ void RepeatedEnumFieldGenerator::GenerateByteSize(io::Printer* printer) const {
     format(
         "if (data_size > 0) {\n"
         "  total_size += $tag_size$ +\n"
-        "    ::_pbi::WireFormatLite::Int32Size(static_cast<$int32$>(data_size));\n"
+        "    "
+        "::_pbi::WireFormatLite::Int32Size(static_cast<$int32$>(data_size));\n"
         "}\n"
         "int cached_size = ::_pbi::ToCachedSize(data_size);\n"
         "_$name$_cached_byte_size_.store(cached_size,\n"

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

@@ -81,7 +81,7 @@ std::string GenerateTemplateForOneofString(const FieldDescriptor* descriptor,
   std::string field_name = google::protobuf::compiler::cpp::FieldName(descriptor);
   std::string field_pointer =
       descriptor->options().ctype() == google::protobuf::FieldOptions::STRING
-          ? "$0.GetPointer()"
+          ? "$0.UnsafeGetPointer()"
           : "$0";
 
   if (descriptor->default_value_string().empty()) {
@@ -114,7 +114,7 @@ std::string GenerateTemplateForSingleString(const FieldDescriptor* descriptor,
 
   if (descriptor->options().ctype() == google::protobuf::FieldOptions::STRING) {
     return strings::Substitute(
-        "$0.IsDefault() ? &$1.get() : $0.GetPointer()", field_member,
+        "$0.IsDefault() ? &$1.get() : $0.UnsafeGetPointer()", field_member,
         MakeDefaultName(descriptor));
   }
 
@@ -241,7 +241,12 @@ void SetCommonFieldVariables(const FieldDescriptor* descriptor,
   (*variables)["number"] = StrCat(descriptor->number());
   (*variables)["classname"] = ClassName(FieldScope(descriptor), false);
   (*variables)["declared_type"] = DeclaredTypeMethodName(descriptor->type());
+  // TODO(b/218325252): convert all usages of "field_member" to "field" and
+  // remove this. The former may unnecessarily cause line breaks in protoc code.
+  // Note that the length of variables has no effect on the generated code. It
+  // only affects the readability of code template in protoc.
   (*variables)["field_member"] = FieldMemberName(descriptor);
+  (*variables)["field"] = FieldMemberName(descriptor);
 
   (*variables)["tag_size"] = StrCat(
       WireFormat::TagSize(descriptor->number(), descriptor->type()));

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

@@ -82,6 +82,12 @@ bool CppGenerator::Generate(const FileDescriptor* file,
   // FOO_EXPORT is a macro which should expand to __declspec(dllexport) or
   // __declspec(dllimport) depending on what is being compiled.
   //
+  // If the proto_h option is passed to the compiler, we will generate all
+  // classes and enums so that they can be forward-declared from files that
+  // need them from imports.
+  //
+  // If the lite option is passed to the compiler, we will generate the
+  // current files and all transitive dependencies using the LITE runtime.
   Options file_options;
 
   file_options.opensource_runtime = opensource_runtime_;
@@ -111,6 +117,8 @@ bool CppGenerator::Generate(const FileDescriptor* file,
         file_options.num_cc_files =
             strto32(options[i].second.c_str(), nullptr, 10);
       }
+    } else if (options[i].first == "proto_h") {
+      file_options.proto_h = true;
     } else if (options[i].first == "annotate_accessor") {
       file_options.annotate_accessor = true;
     } else if (options[i].first == "inject_field_listener_events") {

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

@@ -1240,12 +1240,13 @@ void MessageGenerator::GenerateFieldAccessorDefinitions(io::Printer* printer) {
       } else {
         format(
             "inline int $classname$::_internal_$name$_size() const {\n"
-            "  return $name$_$1$.size();\n"
+            "  return $1$$2$.size();\n"
             "}\n"
             "inline int $classname$::$name$_size() const {\n"
             "$annotate_size$"
             "  return _internal_$name$_size();\n"
             "}\n",
+            FieldMemberName(field),
             IsImplicitWeakField(field, options_, scc_analyzer_) &&
                     field->message_type()
                 ? ".weak"
@@ -1391,8 +1392,7 @@ void MessageGenerator::GenerateClassDefinition(io::Printer* printer) {
   if (EnableMessageOwnedArena(descriptor_, options_)) {
     format(
         "inline $classname$() : $classname$("
-        "::$proto_ns$::Arena::InternalHelper<$classname$>::\n"
-        "    CreateMessageOwnedArena(), true) {}\n");
+        "::$proto_ns$::Arena::InternalCreateMessageOwnedArena(), true) {}\n");
   } else {
     format("inline $classname$() : $classname$(nullptr) {}\n");
   }

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

@@ -182,14 +182,13 @@ void MessageFieldGenerator::GenerateInlineAccessorDefinitions(
       // If we're not on an arena, free whatever we were holding before.
       // (If we are on arena, we can just forget the earlier pointer.)
       "  if (GetArenaForAllocation() == nullptr) {\n"
-      "    delete reinterpret_cast<::$proto_ns$::MessageLite*>($name$_);\n"
+      "    delete reinterpret_cast<::$proto_ns$::MessageLite*>($field$);\n"
       "  }\n");
   if (implicit_weak_field_) {
     format(
-        "  $name$_ = "
-        "reinterpret_cast<::$proto_ns$::MessageLite*>($name$);\n");
+        "  $field$ = reinterpret_cast<::$proto_ns$::MessageLite*>($name$);\n");
   } else {
-    format("  $name$_ = $name$;\n");
+    format("  $field$ = $name$;\n");
   }
   format(
       "  if ($name$) {\n"
@@ -207,7 +206,7 @@ void MessageFieldGenerator::GenerateInlineAccessorDefinitions(
       "$annotate_release$"
       "  $clear_hasbit$\n"
       "  $type$* temp = $casted_member$;\n"
-      "  $name$_ = nullptr;\n"
+      "  $field$ = nullptr;\n"
       "#ifdef PROTOBUF_FORCE_COPY_IN_RELEASE\n"
       "  auto* old =  reinterpret_cast<::$proto_ns$::MessageLite*>(temp);\n"
       "  temp = ::$proto_ns$::internal::DuplicateIfNonNull(temp);\n"
@@ -225,7 +224,7 @@ void MessageFieldGenerator::GenerateInlineAccessorDefinitions(
       "$type_reference_function$"
       "  $clear_hasbit$\n"
       "  $type$* temp = $casted_member$;\n"
-      "  $name$_ = nullptr;\n"
+      "  $field$ = nullptr;\n"
       "  return temp;\n"
       "}\n");
 
@@ -233,12 +232,12 @@ void MessageFieldGenerator::GenerateInlineAccessorDefinitions(
       "inline $type$* $classname$::_internal_mutable_$name$() {\n"
       "$type_reference_function$"
       "  $set_hasbit$\n"
-      "  if ($name$_ == nullptr) {\n"
+      "  if ($field$ == nullptr) {\n"
       "    auto* p = CreateMaybeMessage<$type$>(GetArenaForAllocation());\n");
   if (implicit_weak_field_) {
-    format("    $name$_ = reinterpret_cast<::$proto_ns$::MessageLite*>(p);\n");
+    format("    $field$ = reinterpret_cast<::$proto_ns$::MessageLite*>(p);\n");
   } else {
-    format("    $name$_ = p;\n");
+    format("    $field$ = p;\n");
   }
   format(
       "  }\n"
@@ -259,9 +258,9 @@ void MessageFieldGenerator::GenerateInlineAccessorDefinitions(
   format("  if (message_arena == nullptr) {\n");
   if (IsCrossFileMessage(descriptor_)) {
     format(
-        "    delete reinterpret_cast< ::$proto_ns$::MessageLite*>($name$_);\n");
+        "    delete reinterpret_cast< ::$proto_ns$::MessageLite*>($field$);\n");
   } else {
-    format("    delete $name$_;\n");
+    format("    delete $field$;\n");
   }
   format(
       "  }\n"
@@ -271,14 +270,13 @@ void MessageFieldGenerator::GenerateInlineAccessorDefinitions(
     // isn't defined in this file.
     format(
         "    ::$proto_ns$::Arena* submessage_arena =\n"
-        "        ::$proto_ns$::Arena::InternalHelper<\n"
-        "            ::$proto_ns$::MessageLite>::GetOwningArena(\n"
+        "        ::$proto_ns$::Arena::InternalGetOwningArena(\n"
         "                reinterpret_cast<::$proto_ns$::MessageLite*>("
         "$name$));\n");
   } else {
     format(
         "    ::$proto_ns$::Arena* submessage_arena =\n"
-        "        ::$proto_ns$::Arena::InternalHelper<$type$>::GetOwningArena("
+        "        ::$proto_ns$::Arena::InternalGetOwningArena("
         "$name$);\n");
   }
   format(
@@ -291,9 +289,9 @@ void MessageFieldGenerator::GenerateInlineAccessorDefinitions(
       "    $clear_hasbit$\n"
       "  }\n");
   if (implicit_weak_field_) {
-    format("  $name$_ = reinterpret_cast<MessageLite*>($name$);\n");
+    format("  $field$ = reinterpret_cast<MessageLite*>($name$);\n");
   } else {
-    format("  $name$_ = $name$;\n");
+    format("  $field$ = $name$;\n");
   }
   format(
       "$annotate_set$"
@@ -328,8 +326,8 @@ void MessageFieldGenerator::GenerateInternalAccessorDefinitions(
     format(
         "const ::$proto_ns$::MessageLite& $classname$::_Internal::$name$(\n"
         "    const $classname$* msg) {\n"
-        "  if (msg->$field_member$ != nullptr) {\n"
-        "    return *msg->$field_member$;\n"
+        "  if (msg->$field$ != nullptr) {\n"
+        "    return *msg->$field$;\n"
         "  } else {\n"
         "    return *$type_default_instance_ptr$;\n"
         "  }\n"
@@ -341,7 +339,7 @@ void MessageFieldGenerator::GenerateInternalAccessorDefinitions(
       format("  msg->$set_hasbit$\n");
     }
     if (descriptor_->real_containing_oneof() == nullptr) {
-      format("  if (msg->$field_member$ == nullptr) {\n");
+      format("  if (msg->$field$ == nullptr) {\n");
     } else {
       format(
           "  if (!msg->_internal_has_$name$()) {\n"
@@ -349,10 +347,10 @@ void MessageFieldGenerator::GenerateInternalAccessorDefinitions(
           "    msg->set_has_$name$();\n");
     }
     format(
-        "    msg->$field_member$ = $type_default_instance_ptr$->New(\n"
+        "    msg->$field$ = $type_default_instance_ptr$->New(\n"
         "        msg->GetArenaForAllocation());\n"
         "  }\n"
-        "  return msg->$field_member$;\n"
+        "  return msg->$field$;\n"
         "}\n");
   } else {
     // This inline accessor directly returns member field and is used in
@@ -361,7 +359,7 @@ void MessageFieldGenerator::GenerateInternalAccessorDefinitions(
     format(
         "const $type$&\n"
         "$classname$::_Internal::$name$(const $classname$* msg) {\n"
-        "  return *msg->$field_member$;\n"
+        "  return *msg->$field$;\n"
         "}\n");
   }
 }
@@ -374,12 +372,12 @@ void MessageFieldGenerator::GenerateClearingCode(io::Printer* printer) const {
     // If we don't have has-bits, message presence is indicated only by ptr !=
     // nullptr. Thus on clear, we need to delete the object.
     format(
-        "if (GetArenaForAllocation() == nullptr && $name$_ != nullptr) {\n"
-        "  delete $name$_;\n"
+        "if (GetArenaForAllocation() == nullptr && $field$ != nullptr) {\n"
+        "  delete $field$;\n"
         "}\n"
-        "$name$_ = nullptr;\n");
+        "$field$ = nullptr;\n");
   } else {
-    format("if ($name$_ != nullptr) $name$_->Clear();\n");
+    format("if ($field$ != nullptr) $field$->Clear();\n");
   }
 }
 
@@ -392,14 +390,14 @@ void MessageFieldGenerator::GenerateMessageClearingCode(
     // If we don't have has-bits, message presence is indicated only by ptr !=
     // nullptr. Thus on clear, we need to delete the object.
     format(
-        "if (GetArenaForAllocation() == nullptr && $name$_ != nullptr) {\n"
-        "  delete $name$_;\n"
+        "if (GetArenaForAllocation() == nullptr && $field$ != nullptr) {\n"
+        "  delete $field$;\n"
         "}\n"
-        "$name$_ = nullptr;\n");
+        "$field$ = nullptr;\n");
   } else {
     format(
-        "$DCHK$($name$_ != nullptr);\n"
-        "$name$_->Clear();\n");
+        "$DCHK$($field$ != nullptr);\n"
+        "$field$->Clear();\n");
   }
 }
 
@@ -422,7 +420,7 @@ void MessageFieldGenerator::GenerateSwappingCode(io::Printer* printer) const {
   GOOGLE_CHECK(!IsFieldStripped(descriptor_, options_));
 
   Formatter format(printer, variables_);
-  format("swap($name$_, other->$name$_);\n");
+  format("swap($field$, other->$field$);\n");
 }
 
 void MessageFieldGenerator::GenerateDestructorCode(io::Printer* printer) const {
@@ -487,7 +485,7 @@ void MessageFieldGenerator::GenerateByteSize(io::Printer* printer) const {
   format(
       "total_size += $tag_size$ +\n"
       "  ::$proto_ns$::internal::WireFormatLite::$declared_type$Size(\n"
-      "    *$field_member$);\n");
+      "    *$field$);\n");
 }
 
 void MessageFieldGenerator::GenerateIsInitialized(io::Printer* printer) const {
@@ -498,7 +496,7 @@ void MessageFieldGenerator::GenerateIsInitialized(io::Printer* printer) const {
   Formatter format(printer, variables_);
   format(
       "if (_internal_has_$name$()) {\n"
-      "  if (!$name$_->IsInitialized()) return false;\n"
+      "  if (!$field$->IsInitialized()) return false;\n"
       "}\n");
 }
 
@@ -532,15 +530,13 @@ void MessageOneofFieldGenerator::GenerateNonInlineAccessorDefinitions(
     // isn't defined in this file.
     format(
         "    ::$proto_ns$::Arena* submessage_arena =\n"
-        "        ::$proto_ns$::Arena::InternalHelper<\n"
-        "            ::$proto_ns$::MessageLite>::GetOwningArena(\n"
+        "        ::$proto_ns$::Arena::InternalGetOwningArena(\n"
         "                reinterpret_cast<::$proto_ns$::MessageLite*>("
         "$name$));\n");
   } else {
     format(
         "    ::$proto_ns$::Arena* submessage_arena =\n"
-        "      ::$proto_ns$::Arena::InternalHelper<"
-        "$type$>::GetOwningArena($name$);\n");
+        "      ::$proto_ns$::Arena::InternalGetOwningArena($name$);\n");
   }
   format(
       "    if (message_arena != submessage_arena) {\n"
@@ -548,7 +544,7 @@ void MessageOneofFieldGenerator::GenerateNonInlineAccessorDefinitions(
       "          message_arena, $name$, submessage_arena);\n"
       "    }\n"
       "    set_has_$name$();\n"
-      "    $field_member$ = $name$;\n"
+      "    $field$ = $name$;\n"
       "  }\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set_allocated:$full_name$)\n"
@@ -569,7 +565,7 @@ void MessageOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "    if (GetArenaForAllocation() != nullptr) {\n"
       "      temp = ::$proto_ns$::internal::DuplicateIfNonNull(temp);\n"
       "    }\n"
-      "    $field_member$ = nullptr;\n"
+      "    $field$ = nullptr;\n"
       "    return temp;\n"
       "  } else {\n"
       "    return nullptr;\n"
@@ -596,7 +592,7 @@ void MessageOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "  if (_internal_has_$name$()) {\n"
       "    clear_has_$oneof_name$();\n"
       "    $type$* temp = $casted_member$;\n"
-      "    $field_member$ = nullptr;\n"
+      "    $field$ = nullptr;\n"
       "    return temp;\n"
       "  } else {\n"
       "    return nullptr;\n"
@@ -612,10 +608,10 @@ void MessageOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "    set_has_$name$();\n");
   if (implicit_weak_field_) {
     format(
-        "    $field_member$ = "
+        "    $field$ = "
         "reinterpret_cast<::$proto_ns$::MessageLite*>($name$);\n");
   } else {
-    format("    $field_member$ = $name$;\n");
+    format("    $field$ = $name$;\n");
   }
   format(
       "  }\n"
@@ -630,12 +626,12 @@ void MessageOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "    set_has_$name$();\n");
   if (implicit_weak_field_) {
     format(
-        "    $field_member$ = "
+        "    $field$ = "
         "reinterpret_cast<::$proto_ns$::MessageLite*>(CreateMaybeMessage< "
         "$type$ >(GetArenaForAllocation()));\n");
   } else {
     format(
-        "    $field_member$ = CreateMaybeMessage< $type$ "
+        "    $field$ = CreateMaybeMessage< $type$ "
         ">(GetArenaForAllocation());\n");
   }
   format(
@@ -657,7 +653,7 @@ void MessageOneofFieldGenerator::GenerateClearingCode(
   Formatter format(printer, variables_);
   format(
       "if (GetArenaForAllocation() == nullptr) {\n"
-      "  delete $field_member$;\n"
+      "  delete $field$;\n"
       "}\n");
 }
 
@@ -690,7 +686,7 @@ void MessageOneofFieldGenerator::GenerateIsInitialized(
   Formatter format(printer, variables_);
   format(
       "if (_internal_has_$name$()) {\n"
-      "  if (!$field_member$->IsInitialized()) return false;\n"
+      "  if (!$field$->IsInitialized()) return false;\n"
       "}\n");
 }
 
@@ -769,21 +765,21 @@ void RepeatedMessageFieldGenerator::GenerateInlineAccessorDefinitions(
       // TODO(dlj): move insertion points
       "  // @@protoc_insertion_point(field_mutable:$full_name$)\n"
       "$type_reference_function$"
-      "  return $name$_$weak$.Mutable(index);\n"
+      "  return $field$$weak$.Mutable(index);\n"
       "}\n"
       "inline ::$proto_ns$::RepeatedPtrField< $type$ >*\n"
       "$classname$::mutable_$name$() {\n"
       "$annotate_mutable_list$"
       "  // @@protoc_insertion_point(field_mutable_list:$full_name$)\n"
       "$type_reference_function$"
-      "  return &$name$_$weak$;\n"
+      "  return &$field$$weak$;\n"
       "}\n");
 
   if (options_.safe_boundary_check) {
     format(
         "inline const $type$& $classname$::_internal_$name$(int index) const "
         "{\n"
-        "  return $name$_$weak$.InternalCheckedGet(index,\n"
+        "  return $field$$weak$.InternalCheckedGet(index,\n"
         "      reinterpret_cast<const $type$&>($type_default_instance$));\n"
         "}\n");
   } else {
@@ -791,7 +787,7 @@ void RepeatedMessageFieldGenerator::GenerateInlineAccessorDefinitions(
         "inline const $type$& $classname$::_internal_$name$(int index) const "
         "{\n"
         "$type_reference_function$"
-        "  return $name$_$weak$.Get(index);\n"
+        "  return $field$$weak$.Get(index);\n"
         "}\n");
   }
 
@@ -802,7 +798,7 @@ void RepeatedMessageFieldGenerator::GenerateInlineAccessorDefinitions(
       "  return _internal_$name$(index);\n"
       "}\n"
       "inline $type$* $classname$::_internal_add_$name$() {\n"
-      "  return $name$_$weak$.Add();\n"
+      "  return $field$$weak$.Add();\n"
       "}\n"
       "inline $type$* $classname$::add_$name$() {\n"
       "  $type$* _add = _internal_add_$name$();\n"
@@ -817,7 +813,7 @@ void RepeatedMessageFieldGenerator::GenerateInlineAccessorDefinitions(
       "$annotate_list$"
       "  // @@protoc_insertion_point(field_list:$full_name$)\n"
       "$type_reference_function$"
-      "  return $name$_$weak$;\n"
+      "  return $field$$weak$;\n"
       "}\n");
 }
 
@@ -826,7 +822,7 @@ void RepeatedMessageFieldGenerator::GenerateClearingCode(
   GOOGLE_CHECK(!IsFieldStripped(descriptor_, options_));
 
   Formatter format(printer, variables_);
-  format("$name$_.Clear();\n");
+  format("$field$.Clear();\n");
 }
 
 void RepeatedMessageFieldGenerator::GenerateMergingCode(
@@ -834,7 +830,7 @@ void RepeatedMessageFieldGenerator::GenerateMergingCode(
   GOOGLE_CHECK(!IsFieldStripped(descriptor_, options_));
 
   Formatter format(printer, variables_);
-  format("$name$_.MergeFrom(from.$name$_);\n");
+  format("$field$.MergeFrom(from.$field$);\n");
 }
 
 void RepeatedMessageFieldGenerator::GenerateSwappingCode(
@@ -842,7 +838,7 @@ void RepeatedMessageFieldGenerator::GenerateSwappingCode(
   GOOGLE_CHECK(!IsFieldStripped(descriptor_, options_));
 
   Formatter format(printer, variables_);
-  format("$name$_.InternalSwap(&other->$name$_);\n");
+  format("$field$.InternalSwap(&other->$field$);\n");
 }
 
 void RepeatedMessageFieldGenerator::GenerateConstructorCode(
@@ -857,8 +853,8 @@ void RepeatedMessageFieldGenerator::GenerateSerializeWithCachedSizesToArray(
   Formatter format(printer, variables_);
   if (implicit_weak_field_) {
     format(
-        "for (auto it = this->$name$_.pointer_begin(),\n"
-        "          end = this->$name$_.pointer_end(); it < end; ++it) {\n");
+        "for (auto it = this->$field$.pointer_begin(),\n"
+        "          end = this->$field$.pointer_end(); it < end; ++it) {\n");
     if (descriptor_->type() == FieldDescriptor::TYPE_MESSAGE) {
       format(
           "  target = ::$proto_ns$::internal::WireFormatLite::\n"
@@ -902,7 +898,7 @@ void RepeatedMessageFieldGenerator::GenerateByteSize(
   Formatter format(printer, variables_);
   format(
       "total_size += $tag_size$UL * this->_internal_$name$_size();\n"
-      "for (const auto& msg : this->$name$_) {\n"
+      "for (const auto& msg : this->$field$) {\n"
       "  total_size +=\n"
       "    ::$proto_ns$::internal::WireFormatLite::$declared_type$Size(msg);\n"
       "}\n");
@@ -917,11 +913,11 @@ void RepeatedMessageFieldGenerator::GenerateIsInitialized(
   Formatter format(printer, variables_);
   if (implicit_weak_field_) {
     format(
-        "if (!::$proto_ns$::internal::AllAreInitializedWeak($name$_.weak))\n"
+        "if (!::$proto_ns$::internal::AllAreInitializedWeak($field$.weak))\n"
         "  return false;\n");
   } else {
     format(
-        "if (!::$proto_ns$::internal::AllAreInitialized($name$_))\n"
+        "if (!::$proto_ns$::internal::AllAreInitialized($field$))\n"
         "  return false;\n");
   }
 }

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

@@ -88,8 +88,7 @@ bool IsFieldEligibleForFastParsing(
     return false;
   }
   switch (field->type()) {
-    // Strings, enums, and groups are not handled on the fast path.
-    case FieldDescriptor::TYPE_STRING:
+    // Groups are not handled on the fast path.
     case FieldDescriptor::TYPE_GROUP:
       return false;
 
@@ -105,6 +104,7 @@ bool IsFieldEligibleForFastParsing(
       break;
 
       // Some bytes fields can be handled on fast path.
+    case FieldDescriptor::TYPE_STRING:
     case FieldDescriptor::TYPE_BYTES:
       if (field->options().ctype() != FieldOptions::STRING ||
           !field->default_value_string().empty() ||
@@ -233,15 +233,15 @@ std::vector<const FieldDescriptor*> FilterMiniParsedFields(
         }
         break;
 
-        // TODO(b/209516305): add TYPE_STRING once field names are available.
-      case FieldDescriptor::TYPE_BYTES:
-        if (IsStringInlined(field, options)) {
-          // TODO(b/198211897): support InilnedStringField.
-          handled = false;
-        } else {
-          handled = true;
-        }
-        break;
+        case FieldDescriptor::TYPE_BYTES:
+        case FieldDescriptor::TYPE_STRING:
+          if (IsStringInlined(field, options)) {
+            // TODO(b/198211897): support InilnedStringField.
+            handled = false;
+          } else {
+            handled = true;
+          }
+          break;
 
       case FieldDescriptor::TYPE_MESSAGE:
         // TODO(b/210762816): support remaining field types.
@@ -773,9 +773,9 @@ void ParseFunctionGenerator::GenerateFastFieldEntries(Formatter& format) {
     } else {
       format(
           "{$1$,\n"
-          " {$2$, $3$, $4$, PROTOBUF_FIELD_OFFSET($classname$, $5$_)}},\n",
+          " {$2$, $3$, $4$, PROTOBUF_FIELD_OFFSET($classname$, $5$)}},\n",
           info.func_name, info.coded_tag, info.hasbit_idx, info.aux_idx,
-          FieldName(info.field));
+          FieldMemberName(info.field));
     }
   }
 }
@@ -999,7 +999,7 @@ void ParseFunctionGenerator::GenerateArenaString(Formatter& format,
                 "::" + MakeDefaultName(field) + ".get()";
   format(
       "if (arena != nullptr) {\n"
-      "  ptr = ctx->ReadArenaString(ptr, &$msg$$name$_, arena");
+      "  ptr = ctx->ReadArenaString(ptr, &$msg$$field$, arena");
   if (IsStringInlined(field, options_)) {
     GOOGLE_DCHECK(!inlined_string_indices_.empty());
     int inlined_string_index = inlined_string_indices_[field->index()];
@@ -1018,10 +1018,9 @@ void ParseFunctionGenerator::GenerateArenaString(Formatter& format,
       ");\n"
       "} else {\n"
       "  ptr = ::_pbi::InlineGreedyStringParser("
-      "$msg$$name$_.MutableNoArenaNoDefault(&$1$), ptr, ctx);\n"
+      "$msg$$field$.MutableNoCopy(nullptr), ptr, ctx);\n"
       "}\n"
-      "const std::string* str = &$msg$$name$_.Get(); (void)str;\n",
-      default_string);
+      "const std::string* str = &$msg$$field$.Get(); (void)str;\n");
 }
 
 void ParseFunctionGenerator::GenerateStrings(Formatter& format,
@@ -1130,13 +1129,13 @@ void ParseFunctionGenerator::GenerateLengthDelim(Formatter& format,
             format(
                 "auto object = "
                 "::$proto_ns$::internal::InitEnumParseWrapper<"
-                "$unknown_fields_type$>(&$msg$$name$_, $1$_IsValid, "
+                "$unknown_fields_type$>(&$msg$$field$, $1$_IsValid, "
                 "$2$, &$msg$_internal_metadata_);\n"
                 "ptr = ctx->ParseMessage(&object, ptr);\n",
                 QualifiedClassName(val->enum_type(), options_),
                 field->number());
           } else {
-            format("ptr = ctx->ParseMessage(&$msg$$name$_, ptr);\n");
+            format("ptr = ctx->ParseMessage(&$msg$$field$, ptr);\n");
           }
         } else if (IsLazy(field, options_, scc_analyzer_)) {
           bool eager_verify =
@@ -1153,19 +1152,19 @@ void ParseFunctionGenerator::GenerateLengthDelim(Formatter& format,
             format(
                 "if (!$msg$_internal_has_$name$()) {\n"
                 "  $msg$clear_$1$();\n"
-                "  $msg$$1$_.$name$_ = ::$proto_ns$::Arena::CreateMessage<\n"
+                "  $msg$$field$ = ::$proto_ns$::Arena::CreateMessage<\n"
                 "      ::$proto_ns$::internal::LazyField>("
                 "$msg$GetArenaForAllocation());\n"
                 "  $msg$set_has_$name$();\n"
                 "}\n"
-                "auto* lazy_field = $msg$$1$_.$name$_;\n",
+                "auto* lazy_field = $msg$$field$;\n",
                 field->containing_oneof()->name());
           } else if (HasHasbit(field)) {
             format(
                 "_Internal::set_has_$name$(&$has_bits$);\n"
-                "auto* lazy_field = &$msg$$name$_;\n");
+                "auto* lazy_field = &$msg$$field$;\n");
           } else {
-            format("auto* lazy_field = &$msg$$name$_;\n");
+            format("auto* lazy_field = &$msg$$field$;\n");
           }
           format(
               "::$proto_ns$::internal::LazyFieldParseHelper<\n"
@@ -1188,7 +1187,7 @@ void ParseFunctionGenerator::GenerateLengthDelim(Formatter& format,
                 "ptr);\n");
           } else {
             format(
-                "ptr = ctx->ParseMessage($msg$$name$_.AddWeak("
+                "ptr = ctx->ParseMessage($msg$$field$.AddWeak("
                 "reinterpret_cast<const ::$proto_ns$::MessageLite*>($1$ptr_)"
                 "), ptr);\n",
                 QualifiedDefaultInstanceName(field->message_type(), options_));
@@ -1287,7 +1286,7 @@ void ParseFunctionGenerator::GenerateFieldBody(
             format("_Internal::set_has_$name$(&$has_bits$);\n");
           }
           format(
-              "$msg$$name$_ = ::$proto_ns$::internal::ReadVarint$1$$2$(&ptr);\n"
+              "$msg$$field$ = ::$proto_ns$::internal::ReadVarint$1$$2$(&ptr);\n"
               "CHK_(ptr);\n",
               zigzag, size);
         }
@@ -1434,6 +1433,8 @@ void ParseFunctionGenerator::GenerateFieldSwitch(
   format.Indent();
 
   for (const auto* field : fields) {
+    // Set abbreviated form instead of field_member.
+    format.Set("field", FieldMemberName(field));
     PrintFieldComment(format, field);
     format("case $1$:\n", field->number());
     format.Indent();

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

@@ -150,7 +150,7 @@ void PrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
   Formatter format(printer, variables_);
   format(
       "inline $type$ $classname$::_internal_$name$() const {\n"
-      "  return $name$_;\n"
+      "  return $field$;\n"
       "}\n"
       "inline $type$ $classname$::$name$() const {\n"
       "$annotate_get$"
@@ -159,7 +159,7 @@ void PrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
       "}\n"
       "inline void $classname$::_internal_set_$name$($type$ value) {\n"
       "  $set_hasbit$\n"
-      "  $name$_ = value;\n"
+      "  $field$ = value;\n"
       "}\n"
       "inline void $classname$::set_$name$($type$ value) {\n"
       "  _internal_set_$name$(value);\n"
@@ -170,7 +170,7 @@ void PrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
 
 void PrimitiveFieldGenerator::GenerateClearingCode(io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_ = $default$;\n");
+  format("$field$ = $default$;\n");
 }
 
 void PrimitiveFieldGenerator::GenerateMergingCode(io::Printer* printer) const {
@@ -180,7 +180,7 @@ void PrimitiveFieldGenerator::GenerateMergingCode(io::Printer* printer) const {
 
 void PrimitiveFieldGenerator::GenerateSwappingCode(io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("swap($name$_, other->$name$_);\n");
+  format("swap($field$, other->$field$);\n");
 }
 
 void PrimitiveFieldGenerator::GenerateConstructorCode(
@@ -249,7 +249,7 @@ void PrimitiveOneofFieldGenerator::GenerateInlineAccessorDefinitions(
   format(
       "inline $type$ $classname$::_internal_$name$() const {\n"
       "  if (_internal_has_$name$()) {\n"
-      "    return $field_member$;\n"
+      "    return $field$;\n"
       "  }\n"
       "  return $default$;\n"
       "}\n"
@@ -258,7 +258,7 @@ void PrimitiveOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "    clear_$oneof_name$();\n"
       "    set_has_$name$();\n"
       "  }\n"
-      "  $field_member$ = value;\n"
+      "  $field$ = value;\n"
       "}\n"
       "inline $type$ $classname$::$name$() const {\n"
       "$annotate_get$"
@@ -275,7 +275,7 @@ void PrimitiveOneofFieldGenerator::GenerateInlineAccessorDefinitions(
 void PrimitiveOneofFieldGenerator::GenerateClearingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$field_member$ = $default$;\n");
+  format("$field$ = $default$;\n");
 }
 
 void PrimitiveOneofFieldGenerator::GenerateSwappingCode(
@@ -344,7 +344,7 @@ void RepeatedPrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
   Formatter format(printer, variables_);
   format(
       "inline $type$ $classname$::_internal_$name$(int index) const {\n"
-      "  return $name$_.Get(index);\n"
+      "  return $field$.Get(index);\n"
       "}\n"
       "inline $type$ $classname$::$name$(int index) const {\n"
       "$annotate_get$"
@@ -353,11 +353,11 @@ void RepeatedPrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
       "}\n"
       "inline void $classname$::set_$name$(int index, $type$ value) {\n"
       "$annotate_set$"
-      "  $name$_.Set(index, value);\n"
+      "  $field$.Set(index, value);\n"
       "  // @@protoc_insertion_point(field_set:$full_name$)\n"
       "}\n"
       "inline void $classname$::_internal_add_$name$($type$ value) {\n"
-      "  $name$_.Add(value);\n"
+      "  $field$.Add(value);\n"
       "}\n"
       "inline void $classname$::add_$name$($type$ value) {\n"
       "  _internal_add_$name$(value);\n"
@@ -366,7 +366,7 @@ void RepeatedPrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
       "}\n"
       "inline const ::$proto_ns$::RepeatedField< $type$ >&\n"
       "$classname$::_internal_$name$() const {\n"
-      "  return $name$_;\n"
+      "  return $field$;\n"
       "}\n"
       "inline const ::$proto_ns$::RepeatedField< $type$ >&\n"
       "$classname$::$name$() const {\n"
@@ -376,7 +376,7 @@ void RepeatedPrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
       "}\n"
       "inline ::$proto_ns$::RepeatedField< $type$ >*\n"
       "$classname$::_internal_mutable_$name$() {\n"
-      "  return &$name$_;\n"
+      "  return &$field$;\n"
       "}\n"
       "inline ::$proto_ns$::RepeatedField< $type$ >*\n"
       "$classname$::mutable_$name$() {\n"
@@ -389,30 +389,19 @@ void RepeatedPrimitiveFieldGenerator::GenerateInlineAccessorDefinitions(
 void RepeatedPrimitiveFieldGenerator::GenerateClearingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.Clear();\n");
+  format("$field$.Clear();\n");
 }
 
 void RepeatedPrimitiveFieldGenerator::GenerateMergingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.MergeFrom(from.$name$_);\n");
+  format("$field$.MergeFrom(from.$field$);\n");
 }
 
 void RepeatedPrimitiveFieldGenerator::GenerateSwappingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.InternalSwap(&other->$name$_);\n");
-}
-
-void RepeatedPrimitiveFieldGenerator::GenerateConstructorCode(
-    io::Printer* printer) const {
-  // Not needed for repeated fields.
-}
-
-void RepeatedPrimitiveFieldGenerator::GenerateCopyConstructorCode(
-    io::Printer* printer) const {
-  Formatter format(printer, variables_);
-  format("$name$_.CopyFrom(from.$name$_);\n");
+  format("$field$.InternalSwap(&other->$field$);\n");
 }
 
 void RepeatedPrimitiveFieldGenerator::GenerateSerializeWithCachedSizesToArray(
@@ -456,7 +445,7 @@ void RepeatedPrimitiveFieldGenerator::GenerateByteSize(
   if (fixed_size == -1) {
     format(
         "size_t data_size = ::_pbi::WireFormatLite::\n"
-        "  $declared_type$Size(this->$name$_);\n");
+        "  $declared_type$Size(this->$field$);\n");
   } else {
     format(
         "unsigned int count = static_cast<unsigned "

src/google/protobuf/compiler/cpp/cpp_primitive_field.h

@@ -98,8 +98,8 @@ class RepeatedPrimitiveFieldGenerator : public FieldGenerator {
   void GenerateClearingCode(io::Printer* printer) const override;
   void GenerateMergingCode(io::Printer* printer) const override;
   void GenerateSwappingCode(io::Printer* printer) const override;
-  void GenerateConstructorCode(io::Printer* printer) const override;
-  void GenerateCopyConstructorCode(io::Printer* printer) const override;
+  void GenerateConstructorCode(io::Printer* printer) const override {}
+  void GenerateCopyConstructorCode(io::Printer* printer) const override {}
   void GenerateSerializeWithCachedSizesToArray(
       io::Printer* printer) const override;
   void GenerateByteSize(io::Printer* printer) const override;

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

@@ -54,8 +54,6 @@ void SetStringVariables(const FieldDescriptor* descriptor,
 
   const std::string kNS = "::" + (*variables)["proto_ns"] + "::internal::";
   const std::string kArenaStringPtr = kNS + "ArenaStringPtr";
-  const std::string kEmptyDefault = kArenaStringPtr + "::EmptyDefault{}";
-  const std::string kNonEmptyDefault = kArenaStringPtr + "::NonEmptyDefault{}";
 
   (*variables)["default"] = DefaultValue(options, descriptor);
   (*variables)["default_length"] =
@@ -64,21 +62,17 @@ void SetStringVariables(const FieldDescriptor* descriptor,
   (*variables)["default_variable_name"] = default_variable_string;
 
   if (descriptor->default_value_string().empty()) {
-    (*variables)["init_value"] = "";
     (*variables)["default_string"] = kNS + "GetEmptyStringAlreadyInited()";
     (*variables)["default_value"] = "&" + (*variables)["default_string"];
-    (*variables)["default_value_tag"] = kEmptyDefault;
-    (*variables)["default_variable_or_tag"] = kEmptyDefault;
+    (*variables)["lazy_variable_args"] = "";
   } else {
     (*variables)["lazy_variable"] =
         QualifiedClassName(descriptor->containing_type(), options) +
         "::" + default_variable_string;
 
-    (*variables)["init_value"] = "nullptr";
     (*variables)["default_string"] = (*variables)["lazy_variable"] + ".get()";
     (*variables)["default_value"] = "nullptr";
-    (*variables)["default_value_tag"] = kNonEmptyDefault;
-    (*variables)["default_variable_or_tag"] = (*variables)["lazy_variable"];
+    (*variables)["lazy_variable_args"] = (*variables)["lazy_variable"] + ", ";
   }
 
   (*variables)["pointer_type"] =
@@ -210,7 +204,7 @@ void StringFieldGenerator::GenerateInlineAccessorDefinitions(
       "  // @@protoc_insertion_point(field_get:$full_name$)\n");
   if (!descriptor_->default_value_string().empty()) {
     format(
-        "  if ($name$_.IsDefault()) return "
+        "  if ($field$.IsDefault()) return "
         "$default_variable_name$.get();\n");
   }
   format(
@@ -222,7 +216,7 @@ void StringFieldGenerator::GenerateInlineAccessorDefinitions(
         "inline PROTOBUF_ALWAYS_INLINE\n"
         "void $classname$::set_$name$(ArgT0&& arg0, ArgT... args) {\n"
         " $set_hasbit$\n"
-        " $name$_.$setter$($default_value_tag$, static_cast<ArgT0 &&>(arg0),"
+        " $field$.$setter$(static_cast<ArgT0 &&>(arg0),"
         " args..., GetArenaForAllocation());\n"
         "$annotate_set$"
         "  // @@protoc_insertion_point(field_set:$full_name$)\n"
@@ -233,7 +227,7 @@ void StringFieldGenerator::GenerateInlineAccessorDefinitions(
         "inline PROTOBUF_ALWAYS_INLINE\n"
         "void $classname$::set_$name$(ArgT0&& arg0, ArgT... args) {\n"
         " $set_hasbit$\n"
-        " $name$_.$setter$(nullptr, static_cast<ArgT0 &&>(arg0),"
+        " $field$.$setter$(static_cast<ArgT0 &&>(arg0),"
         " args..., GetArenaForAllocation(), _internal_$name$_donated(), "
         "&$donating_states_word$, $mask_for_undonate$, this);\n"
         "$annotate_set$"
@@ -252,18 +246,18 @@ void StringFieldGenerator::GenerateInlineAccessorDefinitions(
       "  return _s;\n"
       "}\n"
       "inline const std::string& $classname$::_internal_$name$() const {\n"
-      "  return $name$_.Get();\n"
+      "  return $field$.Get();\n"
       "}\n"
       "inline void $classname$::_internal_set_$name$(const std::string& "
       "value) {\n"
       "  $set_hasbit$\n");
   if (!inlined_) {
     format(
-        "  $name$_.Set($default_value_tag$, value, GetArenaForAllocation());\n"
+        "  $field$.Set(value, GetArenaForAllocation());\n"
         "}\n");
   } else {
     format(
-        "  $name$_.Set(nullptr, value, GetArenaForAllocation(),\n"
+        "  $field$.Set(value, GetArenaForAllocation(),\n"
         "    _internal_$name$_donated(), &$donating_states_word$, "
         "$mask_for_undonate$, this);\n"
         "}\n");
@@ -273,12 +267,12 @@ void StringFieldGenerator::GenerateInlineAccessorDefinitions(
       "  $set_hasbit$\n");
   if (!inlined_) {
     format(
-        "  return $name$_.Mutable($default_variable_or_tag$, "
+        "  return $field$.Mutable($lazy_variable_args$"
         "GetArenaForAllocation());\n"
         "}\n");
   } else {
     format(
-        "  return $name$_.Mutable($default_variable_or_tag$, "
+        "  return $field$.Mutable($lazy_variable_args$"
         "GetArenaForAllocation(), _internal_$name$_donated(), "
         "&$donating_states_word$, $mask_for_undonate$, this);\n"
         "}\n");
@@ -295,26 +289,23 @@ void StringFieldGenerator::GenerateInlineAccessorDefinitions(
         "  }\n"
         "  $clear_hasbit$\n");
     if (!inlined_) {
-      format(
-          "  auto* p = $name$_.ReleaseNonDefault($default_value$, "
-          "GetArenaForAllocation());\n");
+      format("  auto* p = $field$.Release();\n");
       if (descriptor_->default_value_string().empty()) {
         format(
             "#ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING\n"
-            "  if ($name$_.IsDefault()) {\n"
-            "    $name$_.Set($default_value$, \"\", GetArenaForAllocation());\n"
+            "  if ($field$.IsDefault()) {\n"
+            "    $field$.Set(\"\", GetArenaForAllocation());\n"
             "  }\n"
             "#endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING\n");
       }
       format("  return p;\n");
     } else {
       format(
-          "  return $name$_.Release(nullptr, GetArenaForAllocation(), "
+          "  return $field$.Release(GetArenaForAllocation(), "
           "_internal_$name$_donated());\n");
     }
   } else {
-    format(
-        "  return $name$_.Release($default_value$, GetArenaForAllocation());\n");
+    format("  return $field$.Release();\n");
   }
 
   format(
@@ -326,21 +317,19 @@ void StringFieldGenerator::GenerateInlineAccessorDefinitions(
       "    $clear_hasbit$\n"
       "  }\n");
   if (!inlined_) {
-    format(
-        "  $name$_.SetAllocated($default_value$, $name$,\n"
-        "      GetArenaForAllocation());\n");
+    format("  $field$.SetAllocated($name$, GetArenaForAllocation());\n");
     if (descriptor_->default_value_string().empty()) {
       format(
           "#ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING\n"
-          "  if ($name$_.IsDefault()) {\n"
-          "    $name$_.Set($default_value$, \"\", GetArenaForAllocation());\n"
+          "  if ($field$.IsDefault()) {\n"
+          "    $field$.Set(\"\", GetArenaForAllocation());\n"
           "  }\n"
           "#endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING\n");
     }
   } else {
     // Currently, string fields with default value can't be inlined.
     format(
-        "    $name$_.SetAllocated(nullptr, $name$, GetArenaForAllocation(), "
+        "    $field$.SetAllocated(nullptr, $name$, GetArenaForAllocation(), "
         "_internal_$name$_donated(), &$donating_states_word$, "
         "$mask_for_undonate$, this);\n");
   }
@@ -364,11 +353,11 @@ void StringFieldGenerator::GenerateNonInlineAccessorDefinitions(
 void StringFieldGenerator::GenerateClearingCode(io::Printer* printer) const {
   Formatter format(printer, variables_);
   if (descriptor_->default_value_string().empty()) {
-    format("$name$_.ClearToEmpty();\n");
+    format("$field$.ClearToEmpty();\n");
   } else {
     GOOGLE_DCHECK(!inlined_);
     format(
-        "$name$_.ClearToDefault($lazy_variable$, GetArenaForAllocation());\n");
+        "$field$.ClearToDefault($lazy_variable$, GetArenaForAllocation());\n");
   }
 }
 
@@ -394,20 +383,20 @@ void StringFieldGenerator::GenerateMessageClearingCode(
     //
     // For non-inlined strings, we distinguish from non-default by comparing
     // instances, rather than contents.
-    format("$DCHK$(!$name$_.IsDefault());\n");
+    format("$DCHK$(!$field$.IsDefault());\n");
   }
 
   if (descriptor_->default_value_string().empty()) {
     if (must_be_present) {
-      format("$name$_.ClearNonDefaultToEmpty();\n");
+      format("$field$.ClearNonDefaultToEmpty();\n");
     } else {
-      format("$name$_.ClearToEmpty();\n");
+      format("$field$.ClearToEmpty();\n");
     }
   } else {
     // Clear to a non-empty default is more involved, as we try to use the
     // Arena if one is present and may need to reallocate the string.
     format(
-        "$name$_.ClearToDefault($lazy_variable$, GetArenaForAllocation());\n ");
+        "$field$.ClearToDefault($lazy_variable$, GetArenaForAllocation());\n ");
   }
 }
 
@@ -422,16 +411,15 @@ void StringFieldGenerator::GenerateSwappingCode(io::Printer* printer) const {
   if (!inlined_) {
     format(
         "::$proto_ns$::internal::ArenaStringPtr::InternalSwap(\n"
-        "    $default_value$,\n"
-        "    &$name$_, lhs_arena,\n"
-        "    &other->$name$_, rhs_arena\n"
+        "    &$field$, lhs_arena,\n"
+        "    &other->$field$, rhs_arena\n"
         ");\n");
   } else {
     format(
         "::$proto_ns$::internal::InlinedStringField::InternalSwap(\n"
-        "  &$name$_, lhs_arena, "
+        "  &$field$, lhs_arena, "
         "(_inlined_string_donated_[0] & 0x1u) == 0, this,\n"
-        "  &other->$name$_, rhs_arena, "
+        "  &other->$field$, rhs_arena, "
         "(other->_inlined_string_donated_[0] & 0x1u) == 0, other);\n");
   }
 }
@@ -442,12 +430,12 @@ void StringFieldGenerator::GenerateConstructorCode(io::Printer* printer) const {
     return;
   }
   GOOGLE_DCHECK(!inlined_);
-  format("$name$_.InitDefault($init_value$);\n");
+  format("$name$_.InitDefault();\n");
   if (IsString(descriptor_, options_) &&
       descriptor_->default_value_string().empty()) {
     format(
         "#ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING\n"
-        "  $name$_.Set($default_value$, \"\", GetArenaForAllocation());\n"
+        "  $name$_.Set(\"\", GetArenaForAllocation());\n"
         "#endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING\n");
   }
 }
@@ -470,11 +458,11 @@ void StringFieldGenerator::GenerateCopyConstructorCode(
 
   if (!inlined_) {
     format(
-        "$name$_.Set($default_value_tag$, from._internal_$name$(), \n"
+        "$field$.Set(from._internal_$name$(), \n"
         "  GetArenaForAllocation());\n");
   } else {
     format(
-        "$name$_.Set(nullptr, from._internal_$name$(),\n"
+        "$field$.Set(from._internal_$name$(),\n"
         "  GetArenaForAllocation(), _internal_$name$_donated(), "
         "&$donating_states_word$, $mask_for_undonate$, this);\n");
   }
@@ -486,14 +474,14 @@ void StringFieldGenerator::GenerateCopyConstructorCode(
 void StringFieldGenerator::GenerateDestructorCode(io::Printer* printer) const {
   Formatter format(printer, variables_);
   if (!inlined_) {
-    format("$name$_.DestroyNoArena($default_value$);\n");
+    format("$field$.Destroy();\n");
     return;
   }
   // Explicitly calls ~InlinedStringField as its automatic call is disabled.
   // Destructor has been implicitly skipped as a union, and even the
   // message-owned arena is enabled, arena could still be missing for
   // Arena::CreateMessage(nullptr).
-  format("$name$_.~InlinedStringField();\n");
+  format("$field$.~InlinedStringField();\n");
 }
 
 ArenaDtorNeeds StringFieldGenerator::NeedsArenaDestructor() const {
@@ -507,7 +495,7 @@ void StringFieldGenerator::GenerateArenaDestructorCode(
   // _this is the object being destructed (we are inside a static method here).
   format(
       "if (!_this->_internal_$name$_donated()) {\n"
-      "  _this->$name$_.~InlinedStringField();\n"
+      "  _this->$field$.~InlinedStringField();\n"
       "}\n");
 }
 
@@ -575,9 +563,9 @@ void StringOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "  if (!_internal_has_$name$()) {\n"
       "    clear_$oneof_name$();\n"
       "    set_has_$name$();\n"
-      "    $field_member$.InitDefault($init_value$);\n"
+      "    $field$.InitDefault();\n"
       "  }\n"
-      "  $field_member$.$setter$($default_value_tag$,"
+      "  $field$.$setter$("
       " static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set:$full_name$)\n"
@@ -590,7 +578,7 @@ void StringOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "}\n"
       "inline const std::string& $classname$::_internal_$name$() const {\n"
       "  if (_internal_has_$name$()) {\n"
-      "    return $field_member$.Get();\n"
+      "    return $field$.Get();\n"
       "  }\n"
       "  return $default_string$;\n"
       "}\n"
@@ -599,28 +587,26 @@ void StringOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "  if (!_internal_has_$name$()) {\n"
       "    clear_$oneof_name$();\n"
       "    set_has_$name$();\n"
-      "    $field_member$.InitDefault($init_value$);\n"
+      "    $field$.InitDefault();\n"
       "  }\n"
-      "  $field_member$.Set($default_value_tag$, value, "
-      "GetArenaForAllocation());\n"
+      "  $field$.Set(value, GetArenaForAllocation());\n"
       "}\n");
   format(
       "inline std::string* $classname$::_internal_mutable_$name$() {\n"
       "  if (!_internal_has_$name$()) {\n"
       "    clear_$oneof_name$();\n"
       "    set_has_$name$();\n"
-      "    $field_member$.InitDefault($init_value$);\n"
+      "    $field$.InitDefault();\n"
       "  }\n"
-      "  return $field_member$.Mutable(\n"
-      "      $default_variable_or_tag$, GetArenaForAllocation());\n"
+      "  return $field$.Mutable($lazy_variable_args$"
+      "      GetArenaForAllocation());\n"
       "}\n"
       "inline std::string* $classname$::$release_name$() {\n"
       "$annotate_release$"
       "  // @@protoc_insertion_point(field_release:$full_name$)\n"
       "  if (_internal_has_$name$()) {\n"
       "    clear_has_$oneof_name$();\n"
-      "    return $field_member$.ReleaseNonDefault($default_value$, "
-      "GetArenaForAllocation());\n"
+      "    return $field$.Release();\n"
       "  } else {\n"
       "    return nullptr;\n"
       "  }\n"
@@ -631,7 +617,7 @@ void StringOneofFieldGenerator::GenerateInlineAccessorDefinitions(
       "  }\n"
       "  if ($name$ != nullptr) {\n"
       "    set_has_$name$();\n"
-      "    $field_member$.InitAllocated($name$, GetArenaForAllocation());\n"
+      "    $field$.InitAllocated($name$, GetArenaForAllocation());\n"
       "  }\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set_allocated:$full_name$)\n"
@@ -641,9 +627,7 @@ void StringOneofFieldGenerator::GenerateInlineAccessorDefinitions(
 void StringOneofFieldGenerator::GenerateClearingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format(
-      "$field_member$.Destroy($default_value_tag$, "
-      "GetArenaForAllocation());\n");
+  format("$field$.Destroy();\n");
 }
 
 void StringOneofFieldGenerator::GenerateMessageClearingCode(
@@ -758,14 +742,14 @@ void RepeatedStringFieldGenerator::GenerateInlineAccessorDefinitions(
     format(
         "inline const std::string& $classname$::_internal_$name$(int index) "
         "const {\n"
-        "  return $name$_.InternalCheckedGet(\n"
+        "  return $field$.InternalCheckedGet(\n"
         "      index, ::$proto_ns$::internal::GetEmptyStringAlreadyInited());\n"
         "}\n");
   } else {
     format(
         "inline const std::string& $classname$::_internal_$name$(int index) "
         "const {\n"
-        "  return $name$_.Get(index);\n"
+        "  return $field$.Get(index);\n"
         "}\n");
   }
   format(
@@ -777,23 +761,23 @@ void RepeatedStringFieldGenerator::GenerateInlineAccessorDefinitions(
       "inline std::string* $classname$::mutable_$name$(int index) {\n"
       "$annotate_mutable$"
       "  // @@protoc_insertion_point(field_mutable:$full_name$)\n"
-      "  return $name$_.Mutable(index);\n"
+      "  return $field$.Mutable(index);\n"
       "}\n"
       "inline void $classname$::set_$name$(int index, const std::string& "
       "value) "
       "{\n"
-      "  $name$_.Mutable(index)->assign(value);\n"
+      "  $field$.Mutable(index)->assign(value);\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set:$full_name$)\n"
       "}\n"
       "inline void $classname$::set_$name$(int index, std::string&& value) {\n"
-      "  $name$_.Mutable(index)->assign(std::move(value));\n"
+      "  $field$.Mutable(index)->assign(std::move(value));\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set:$full_name$)\n"
       "}\n"
       "inline void $classname$::set_$name$(int index, const char* value) {\n"
       "  $null_check$"
-      "  $name$_.Mutable(index)->assign(value);\n"
+      "  $field$.Mutable(index)->assign(value);\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set_char:$full_name$)\n"
       "}\n");
@@ -801,7 +785,7 @@ void RepeatedStringFieldGenerator::GenerateInlineAccessorDefinitions(
     format(
         "inline void "
         "$classname$::set_$name$(int index, StringPiece value) {\n"
-        "  $name$_.Mutable(index)->assign(value.data(), value.size());\n"
+        "  $field$.Mutable(index)->assign(value.data(), value.size());\n"
         "$annotate_set$"
         "  // @@protoc_insertion_point(field_set_string_piece:$full_name$)\n"
         "}\n");
@@ -810,34 +794,34 @@ void RepeatedStringFieldGenerator::GenerateInlineAccessorDefinitions(
       "inline void "
       "$classname$::set_$name$"
       "(int index, const $pointer_type$* value, size_t size) {\n"
-      "  $name$_.Mutable(index)->assign(\n"
+      "  $field$.Mutable(index)->assign(\n"
       "    reinterpret_cast<const char*>(value), size);\n"
       "$annotate_set$"
       "  // @@protoc_insertion_point(field_set_pointer:$full_name$)\n"
       "}\n"
       "inline std::string* $classname$::_internal_add_$name$() {\n"
-      "  return $name$_.Add();\n"
+      "  return $field$.Add();\n"
       "}\n"
       "inline void $classname$::add_$name$(const std::string& value) {\n"
-      "  $name$_.Add()->assign(value);\n"
+      "  $field$.Add()->assign(value);\n"
       "$annotate_add$"
       "  // @@protoc_insertion_point(field_add:$full_name$)\n"
       "}\n"
       "inline void $classname$::add_$name$(std::string&& value) {\n"
-      "  $name$_.Add(std::move(value));\n"
+      "  $field$.Add(std::move(value));\n"
       "$annotate_add$"
       "  // @@protoc_insertion_point(field_add:$full_name$)\n"
       "}\n"
       "inline void $classname$::add_$name$(const char* value) {\n"
       "  $null_check$"
-      "  $name$_.Add()->assign(value);\n"
+      "  $field$.Add()->assign(value);\n"
       "$annotate_add$"
       "  // @@protoc_insertion_point(field_add_char:$full_name$)\n"
       "}\n");
   if (!options_.opensource_runtime) {
     format(
         "inline void $classname$::add_$name$(StringPiece value) {\n"
-        "  $name$_.Add()->assign(value.data(), value.size());\n"
+        "  $field$.Add()->assign(value.data(), value.size());\n"
         "$annotate_add$"
         "  // @@protoc_insertion_point(field_add_string_piece:$full_name$)\n"
         "}\n");
@@ -845,7 +829,7 @@ void RepeatedStringFieldGenerator::GenerateInlineAccessorDefinitions(
   format(
       "inline void "
       "$classname$::add_$name$(const $pointer_type$* value, size_t size) {\n"
-      "  $name$_.Add()->assign(reinterpret_cast<const char*>(value), size);\n"
+      "  $field$.Add()->assign(reinterpret_cast<const char*>(value), size);\n"
       "$annotate_add$"
       "  // @@protoc_insertion_point(field_add_pointer:$full_name$)\n"
       "}\n"
@@ -853,43 +837,32 @@ void RepeatedStringFieldGenerator::GenerateInlineAccessorDefinitions(
       "$classname$::$name$() const {\n"
       "$annotate_list$"
       "  // @@protoc_insertion_point(field_list:$full_name$)\n"
-      "  return $name$_;\n"
+      "  return $field$;\n"
       "}\n"
       "inline ::$proto_ns$::RepeatedPtrField<std::string>*\n"
       "$classname$::mutable_$name$() {\n"
       "$annotate_mutable_list$"
       "  // @@protoc_insertion_point(field_mutable_list:$full_name$)\n"
-      "  return &$name$_;\n"
+      "  return &$field$;\n"
       "}\n");
 }
 
 void RepeatedStringFieldGenerator::GenerateClearingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.Clear();\n");
+  format("$field$.Clear();\n");
 }
 
 void RepeatedStringFieldGenerator::GenerateMergingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.MergeFrom(from.$name$_);\n");
+  format("$field$.MergeFrom(from.$field$);\n");
 }
 
 void RepeatedStringFieldGenerator::GenerateSwappingCode(
     io::Printer* printer) const {
   Formatter format(printer, variables_);
-  format("$name$_.InternalSwap(&other->$name$_);\n");
-}
-
-void RepeatedStringFieldGenerator::GenerateConstructorCode(
-    io::Printer* printer) const {
-  // Not needed for repeated fields.
-}
-
-void RepeatedStringFieldGenerator::GenerateCopyConstructorCode(
-    io::Printer* printer) const {
-  Formatter format(printer, variables_);
-  format("$name$_.CopyFrom(from.$name$_);");
+  format("$field$.InternalSwap(&other->$field$);\n");
 }
 
 void RepeatedStringFieldGenerator::GenerateSerializeWithCachedSizesToArray(
@@ -916,11 +889,11 @@ void RepeatedStringFieldGenerator::GenerateByteSize(
   Formatter format(printer, variables_);
   format(
       "total_size += $tag_size$ *\n"
-      "    ::$proto_ns$::internal::FromIntSize($name$_.size());\n"
-      "for (int i = 0, n = $name$_.size(); i < n; i++) {\n"
+      "    ::$proto_ns$::internal::FromIntSize($field$.size());\n"
+      "for (int i = 0, n = $field$.size(); i < n; i++) {\n"
       "  total_size += "
       "::$proto_ns$::internal::WireFormatLite::$declared_type$Size(\n"
-      "    $name$_.Get(i));\n"
+      "    $field$.Get(i));\n"
       "}\n");
 }
 

src/google/protobuf/compiler/cpp/cpp_string_field.h

@@ -111,8 +111,8 @@ class RepeatedStringFieldGenerator : public FieldGenerator {
   void GenerateClearingCode(io::Printer* printer) const override;
   void GenerateMergingCode(io::Printer* printer) const override;
   void GenerateSwappingCode(io::Printer* printer) const override;
-  void GenerateConstructorCode(io::Printer* printer) const override;
-  void GenerateCopyConstructorCode(io::Printer* printer) const override;
+  void GenerateConstructorCode(io::Printer* printer) const override {}
+  void GenerateCopyConstructorCode(io::Printer* printer) const override {}
   void GenerateSerializeWithCachedSizesToArray(
       io::Printer* printer) const override;
   void GenerateByteSize(io::Printer* printer) const override;

src/google/protobuf/compiler/parser_unittest.cc

@@ -2466,7 +2466,9 @@ TEST_F(ParseDescriptorDebugTest, TestMaps) {
 //   *output_field to the descriptor of the field, and *output_index to -1.
 // Returns true if the path was valid, false otherwise.  A gTest failure is
 // recorded before returning false.
-bool FollowPath(const Message& root, const int* path_begin, const int* path_end,
+bool FollowPath(const Message& root,
+                RepeatedField<int>::const_iterator path_begin,
+                RepeatedField<int>::const_iterator path_end,
                 const Message** output_message,
                 const FieldDescriptor** output_field, int* output_index) {
   if (path_begin == path_end) {

src/google/protobuf/compiler/plugin.pb.cc

@@ -252,10 +252,10 @@ Version::Version(const Version& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   suffix_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    suffix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    suffix_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_suffix()) {
-    suffix_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_suffix(), 
+    suffix_.Set(from._internal_suffix(), 
       GetArenaForAllocation());
   }
   ::memcpy(&major_, &from.major_,
@@ -267,7 +267,7 @@ Version::Version(const Version& from)
 inline void Version::SharedCtor() {
 suffix_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  suffix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  suffix_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&major_) - reinterpret_cast<char*>(this)),
@@ -286,7 +286,7 @@ Version::~Version() {
 
 inline void Version::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  suffix_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  suffix_.Destroy();
 }
 
 void Version::SetCachedSize(int size) const {
@@ -517,7 +517,6 @@ void Version::InternalSwap(Version* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_has_bits_[0], other->_has_bits_[0]);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &suffix_, lhs_arena,
       &other->suffix_, rhs_arena
   );
@@ -572,10 +571,10 @@ CodeGeneratorRequest::CodeGeneratorRequest(const CodeGeneratorRequest& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   parameter_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    parameter_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    parameter_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_parameter()) {
-    parameter_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_parameter(), 
+    parameter_.Set(from._internal_parameter(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_compiler_version()) {
@@ -589,7 +588,7 @@ CodeGeneratorRequest::CodeGeneratorRequest(const CodeGeneratorRequest& from)
 inline void CodeGeneratorRequest::SharedCtor() {
 parameter_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  parameter_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  parameter_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 compiler_version_ = nullptr;
 }
@@ -605,7 +604,7 @@ CodeGeneratorRequest::~CodeGeneratorRequest() {
 
 inline void CodeGeneratorRequest::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  parameter_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  parameter_.Destroy();
   if (this != internal_default_instance()) delete compiler_version_;
 }
 
@@ -864,7 +863,6 @@ void CodeGeneratorRequest::InternalSwap(CodeGeneratorRequest* other) {
   file_to_generate_.InternalSwap(&other->file_to_generate_);
   proto_file_.InternalSwap(&other->proto_file_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &parameter_, lhs_arena,
       &other->parameter_, rhs_arena
   );
@@ -917,26 +915,26 @@ CodeGeneratorResponse_File::CodeGeneratorResponse_File(const CodeGeneratorRespon
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   insertion_point_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    insertion_point_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    insertion_point_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_insertion_point()) {
-    insertion_point_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_insertion_point(), 
+    insertion_point_.Set(from._internal_insertion_point(), 
       GetArenaForAllocation());
   }
   content_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    content_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    content_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_content()) {
-    content_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_content(), 
+    content_.Set(from._internal_content(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_generated_code_info()) {
@@ -950,15 +948,15 @@ CodeGeneratorResponse_File::CodeGeneratorResponse_File(const CodeGeneratorRespon
 inline void CodeGeneratorResponse_File::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 insertion_point_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  insertion_point_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  insertion_point_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 content_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  content_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  content_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 generated_code_info_ = nullptr;
 }
@@ -974,9 +972,9 @@ CodeGeneratorResponse_File::~CodeGeneratorResponse_File() {
 
 inline void CodeGeneratorResponse_File::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  insertion_point_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  content_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  insertion_point_.Destroy();
+  content_.Destroy();
   if (this != internal_default_instance()) delete generated_code_info_;
 }
 
@@ -1234,17 +1232,14 @@ void CodeGeneratorResponse_File::InternalSwap(CodeGeneratorResponse_File* other)
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_has_bits_[0], other->_has_bits_[0]);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &insertion_point_, lhs_arena,
       &other->insertion_point_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &content_, lhs_arena,
       &other->content_, rhs_arena
   );
@@ -1284,10 +1279,10 @@ CodeGeneratorResponse::CodeGeneratorResponse(const CodeGeneratorResponse& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   error_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    error_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    error_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_error()) {
-    error_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_error(), 
+    error_.Set(from._internal_error(), 
       GetArenaForAllocation());
   }
   supported_features_ = from.supported_features_;
@@ -1297,7 +1292,7 @@ CodeGeneratorResponse::CodeGeneratorResponse(const CodeGeneratorResponse& from)
 inline void CodeGeneratorResponse::SharedCtor() {
 error_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  error_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  error_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 supported_features_ = uint64_t{0u};
 }
@@ -1313,7 +1308,7 @@ CodeGeneratorResponse::~CodeGeneratorResponse() {
 
 inline void CodeGeneratorResponse::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  error_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  error_.Destroy();
 }
 
 void CodeGeneratorResponse::SetCachedSize(int size) const {
@@ -1525,7 +1520,6 @@ void CodeGeneratorResponse::InternalSwap(CodeGeneratorResponse* other) {
   swap(_has_bits_[0], other->_has_bits_[0]);
   file_.InternalSwap(&other->file_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &error_, lhs_arena,
       &other->error_, rhs_arena
   );

src/google/protobuf/compiler/plugin.pb.h

@@ -1093,7 +1093,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Version::set_suffix(ArgT0&& arg0, ArgT... args) {
  _has_bits_[0] |= 0x00000001u;
- suffix_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ suffix_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.compiler.Version.suffix)
 }
 inline std::string* Version::mutable_suffix() {
@@ -1106,11 +1106,11 @@ inline const std::string& Version::_internal_suffix() const {
 }
 inline void Version::_internal_set_suffix(const std::string& value) {
   _has_bits_[0] |= 0x00000001u;
-  suffix_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  suffix_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Version::_internal_mutable_suffix() {
   _has_bits_[0] |= 0x00000001u;
-  return suffix_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return suffix_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Version::release_suffix() {
   // @@protoc_insertion_point(field_release:google.protobuf.compiler.Version.suffix)
@@ -1118,10 +1118,10 @@ inline std::string* Version::release_suffix() {
     return nullptr;
   }
   _has_bits_[0] &= ~0x00000001u;
-  auto* p = suffix_.ReleaseNonDefault(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  auto* p = suffix_.Release();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (suffix_.IsDefault()) {
-    suffix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    suffix_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   return p;
@@ -1132,11 +1132,10 @@ inline void Version::set_allocated_suffix(std::string* suffix) {
   } else {
     _has_bits_[0] &= ~0x00000001u;
   }
-  suffix_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), suffix,
-      GetArenaForAllocation());
+  suffix_.SetAllocated(suffix, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (suffix_.IsDefault()) {
-    suffix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    suffix_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.compiler.Version.suffix)
@@ -1241,7 +1240,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void CodeGeneratorRequest::set_parameter(ArgT0&& arg0, ArgT... args) {
  _has_bits_[0] |= 0x00000001u;
- parameter_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ parameter_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.compiler.CodeGeneratorRequest.parameter)
 }
 inline std::string* CodeGeneratorRequest::mutable_parameter() {
@@ -1254,11 +1253,11 @@ inline const std::string& CodeGeneratorRequest::_internal_parameter() const {
 }
 inline void CodeGeneratorRequest::_internal_set_parameter(const std::string& value) {
   _has_bits_[0] |= 0x00000001u;
-  parameter_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  parameter_.Set(value, GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorRequest::_internal_mutable_parameter() {
   _has_bits_[0] |= 0x00000001u;
-  return parameter_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return parameter_.Mutable(GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorRequest::release_parameter() {
   // @@protoc_insertion_point(field_release:google.protobuf.compiler.CodeGeneratorRequest.parameter)
@@ -1266,10 +1265,10 @@ inline std::string* CodeGeneratorRequest::release_parameter() {
     return nullptr;
   }
   _has_bits_[0] &= ~0x00000001u;
-  auto* p = parameter_.ReleaseNonDefault(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  auto* p = parameter_.Release();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (parameter_.IsDefault()) {
-    parameter_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    parameter_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   return p;
@@ -1280,11 +1279,10 @@ inline void CodeGeneratorRequest::set_allocated_parameter(std::string* parameter
   } else {
     _has_bits_[0] &= ~0x00000001u;
   }
-  parameter_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), parameter,
-      GetArenaForAllocation());
+  parameter_.SetAllocated(parameter, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (parameter_.IsDefault()) {
-    parameter_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    parameter_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.compiler.CodeGeneratorRequest.parameter)
@@ -1404,7 +1402,7 @@ inline void CodeGeneratorRequest::set_allocated_compiler_version(::PROTOBUF_NAME
   }
   if (compiler_version) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-        ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<::PROTOBUF_NAMESPACE_ID::compiler::Version>::GetOwningArena(compiler_version);
+        ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(compiler_version);
     if (message_arena != submessage_arena) {
       compiler_version = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(
           message_arena, compiler_version, submessage_arena);
@@ -1441,7 +1439,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void CodeGeneratorResponse_File::set_name(ArgT0&& arg0, ArgT... args) {
  _has_bits_[0] |= 0x00000001u;
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.compiler.CodeGeneratorResponse.File.name)
 }
 inline std::string* CodeGeneratorResponse_File::mutable_name() {
@@ -1454,11 +1452,11 @@ inline const std::string& CodeGeneratorResponse_File::_internal_name() const {
 }
 inline void CodeGeneratorResponse_File::_internal_set_name(const std::string& value) {
   _has_bits_[0] |= 0x00000001u;
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse_File::_internal_mutable_name() {
   _has_bits_[0] |= 0x00000001u;
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse_File::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.compiler.CodeGeneratorResponse.File.name)
@@ -1466,10 +1464,10 @@ inline std::string* CodeGeneratorResponse_File::release_name() {
     return nullptr;
   }
   _has_bits_[0] &= ~0x00000001u;
-  auto* p = name_.ReleaseNonDefault(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  auto* p = name_.Release();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   return p;
@@ -1480,11 +1478,10 @@ inline void CodeGeneratorResponse_File::set_allocated_name(std::string* name) {
   } else {
     _has_bits_[0] &= ~0x00000001u;
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.compiler.CodeGeneratorResponse.File.name)
@@ -1510,7 +1507,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void CodeGeneratorResponse_File::set_insertion_point(ArgT0&& arg0, ArgT... args) {
  _has_bits_[0] |= 0x00000002u;
- insertion_point_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ insertion_point_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.compiler.CodeGeneratorResponse.File.insertion_point)
 }
 inline std::string* CodeGeneratorResponse_File::mutable_insertion_point() {
@@ -1523,11 +1520,11 @@ inline const std::string& CodeGeneratorResponse_File::_internal_insertion_point(
 }
 inline void CodeGeneratorResponse_File::_internal_set_insertion_point(const std::string& value) {
   _has_bits_[0] |= 0x00000002u;
-  insertion_point_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  insertion_point_.Set(value, GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse_File::_internal_mutable_insertion_point() {
   _has_bits_[0] |= 0x00000002u;
-  return insertion_point_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return insertion_point_.Mutable(GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse_File::release_insertion_point() {
   // @@protoc_insertion_point(field_release:google.protobuf.compiler.CodeGeneratorResponse.File.insertion_point)
@@ -1535,10 +1532,10 @@ inline std::string* CodeGeneratorResponse_File::release_insertion_point() {
     return nullptr;
   }
   _has_bits_[0] &= ~0x00000002u;
-  auto* p = insertion_point_.ReleaseNonDefault(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  auto* p = insertion_point_.Release();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (insertion_point_.IsDefault()) {
-    insertion_point_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    insertion_point_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   return p;
@@ -1549,11 +1546,10 @@ inline void CodeGeneratorResponse_File::set_allocated_insertion_point(std::strin
   } else {
     _has_bits_[0] &= ~0x00000002u;
   }
-  insertion_point_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), insertion_point,
-      GetArenaForAllocation());
+  insertion_point_.SetAllocated(insertion_point, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (insertion_point_.IsDefault()) {
-    insertion_point_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    insertion_point_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.compiler.CodeGeneratorResponse.File.insertion_point)
@@ -1579,7 +1575,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void CodeGeneratorResponse_File::set_content(ArgT0&& arg0, ArgT... args) {
  _has_bits_[0] |= 0x00000004u;
- content_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ content_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.compiler.CodeGeneratorResponse.File.content)
 }
 inline std::string* CodeGeneratorResponse_File::mutable_content() {
@@ -1592,11 +1588,11 @@ inline const std::string& CodeGeneratorResponse_File::_internal_content() const
 }
 inline void CodeGeneratorResponse_File::_internal_set_content(const std::string& value) {
   _has_bits_[0] |= 0x00000004u;
-  content_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  content_.Set(value, GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse_File::_internal_mutable_content() {
   _has_bits_[0] |= 0x00000004u;
-  return content_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return content_.Mutable(GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse_File::release_content() {
   // @@protoc_insertion_point(field_release:google.protobuf.compiler.CodeGeneratorResponse.File.content)
@@ -1604,10 +1600,10 @@ inline std::string* CodeGeneratorResponse_File::release_content() {
     return nullptr;
   }
   _has_bits_[0] &= ~0x00000004u;
-  auto* p = content_.ReleaseNonDefault(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  auto* p = content_.Release();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (content_.IsDefault()) {
-    content_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    content_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   return p;
@@ -1618,11 +1614,10 @@ inline void CodeGeneratorResponse_File::set_allocated_content(std::string* conte
   } else {
     _has_bits_[0] &= ~0x00000004u;
   }
-  content_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), content,
-      GetArenaForAllocation());
+  content_.SetAllocated(content, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (content_.IsDefault()) {
-    content_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    content_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.compiler.CodeGeneratorResponse.File.content)
@@ -1701,8 +1696,7 @@ inline void CodeGeneratorResponse_File::set_allocated_generated_code_info(::PROT
   }
   if (generated_code_info) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-        ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<
-            ::PROTOBUF_NAMESPACE_ID::MessageLite>::GetOwningArena(
+        ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(
                 reinterpret_cast<::PROTOBUF_NAMESPACE_ID::MessageLite*>(generated_code_info));
     if (message_arena != submessage_arena) {
       generated_code_info = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(
@@ -1740,7 +1734,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void CodeGeneratorResponse::set_error(ArgT0&& arg0, ArgT... args) {
  _has_bits_[0] |= 0x00000001u;
- error_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ error_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.compiler.CodeGeneratorResponse.error)
 }
 inline std::string* CodeGeneratorResponse::mutable_error() {
@@ -1753,11 +1747,11 @@ inline const std::string& CodeGeneratorResponse::_internal_error() const {
 }
 inline void CodeGeneratorResponse::_internal_set_error(const std::string& value) {
   _has_bits_[0] |= 0x00000001u;
-  error_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  error_.Set(value, GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse::_internal_mutable_error() {
   _has_bits_[0] |= 0x00000001u;
-  return error_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return error_.Mutable(GetArenaForAllocation());
 }
 inline std::string* CodeGeneratorResponse::release_error() {
   // @@protoc_insertion_point(field_release:google.protobuf.compiler.CodeGeneratorResponse.error)
@@ -1765,10 +1759,10 @@ inline std::string* CodeGeneratorResponse::release_error() {
     return nullptr;
   }
   _has_bits_[0] &= ~0x00000001u;
-  auto* p = error_.ReleaseNonDefault(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  auto* p = error_.Release();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (error_.IsDefault()) {
-    error_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    error_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   return p;
@@ -1779,11 +1773,10 @@ inline void CodeGeneratorResponse::set_allocated_error(std::string* error) {
   } else {
     _has_bits_[0] &= ~0x00000001u;
   }
-  error_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), error,
-      GetArenaForAllocation());
+  error_.SetAllocated(error, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (error_.IsDefault()) {
-    error_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    error_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.compiler.CodeGeneratorResponse.error)

src/google/protobuf/compiler/subprocess.cc

@@ -73,15 +73,15 @@ static void CloseHandleOrDie(HANDLE handle) {
 
 Subprocess::Subprocess()
     : process_start_error_(ERROR_SUCCESS),
-      child_handle_(NULL),
-      child_stdin_(NULL),
-      child_stdout_(NULL) {}
+      child_handle_(nullptr),
+      child_stdin_(nullptr),
+      child_stdout_(nullptr) {}
 
 Subprocess::~Subprocess() {
-  if (child_stdin_ != NULL) {
+  if (child_stdin_ != nullptr) {
     CloseHandleOrDie(child_stdin_);
   }
-  if (child_stdout_ != NULL) {
+  if (child_stdout_ != nullptr) {
     CloseHandleOrDie(child_stdout_);
   }
 }
@@ -93,10 +93,10 @@ void Subprocess::Start(const std::string& program, SearchMode search_mode) {
   HANDLE stdout_pipe_read;
   HANDLE stdout_pipe_write;
 
-  if (!CreatePipe(&stdin_pipe_read, &stdin_pipe_write, NULL, 0)) {
+  if (!CreatePipe(&stdin_pipe_read, &stdin_pipe_write, nullptr, 0)) {
     GOOGLE_LOG(FATAL) << "CreatePipe: " << Win32ErrorMessage(GetLastError());
   }
-  if (!CreatePipe(&stdout_pipe_read, &stdout_pipe_write, NULL, 0)) {
+  if (!CreatePipe(&stdout_pipe_read, &stdout_pipe_write, nullptr, 0)) {
     GOOGLE_LOG(FATAL) << "CreatePipe: " << Win32ErrorMessage(GetLastError());
   }
 
@@ -134,14 +134,14 @@ void Subprocess::Start(const std::string& program, SearchMode search_mode) {
   // Create the process.
   PROCESS_INFORMATION process_info;
 
-  if (CreateProcessA((search_mode == SEARCH_PATH) ? NULL : program.c_str(),
-                     (search_mode == SEARCH_PATH) ? command_line : NULL,
-                     NULL,  // process security attributes
-                     NULL,  // thread security attributes
-                     TRUE,  // inherit handles?
-                     0,     // obscure creation flags
-                     NULL,  // environment (inherit from parent)
-                     NULL,  // current directory (inherit from parent)
+  if (CreateProcessA((search_mode == SEARCH_PATH) ? nullptr : program.c_str(),
+                     (search_mode == SEARCH_PATH) ? command_line : nullptr,
+                     nullptr,  // process security attributes
+                     nullptr,  // thread security attributes
+                     TRUE,     // inherit handles?
+                     0,        // obscure creation flags
+                     nullptr,  // environment (inherit from parent)
+                     nullptr,  // current directory (inherit from parent)
                      &startup_info, &process_info)) {
     child_handle_ = process_info.hProcess;
     CloseHandleOrDie(process_info.hThread);
@@ -165,28 +165,28 @@ bool Subprocess::Communicate(const Message& input, Message* output,
     return false;
   }
 
-  GOOGLE_CHECK(child_handle_ != NULL) << "Must call Start() first.";
+  GOOGLE_CHECK(child_handle_ != nullptr) << "Must call Start() first.";
 
   std::string input_data = input.SerializeAsString();
   std::string output_data;
 
   int input_pos = 0;
 
-  while (child_stdout_ != NULL) {
+  while (child_stdout_ != nullptr) {
     HANDLE handles[2];
     int handle_count = 0;
 
-    if (child_stdin_ != NULL) {
+    if (child_stdin_ != nullptr) {
       handles[handle_count++] = child_stdin_;
     }
-    if (child_stdout_ != NULL) {
+    if (child_stdout_ != nullptr) {
       handles[handle_count++] = child_stdout_;
     }
 
     DWORD wait_result =
         WaitForMultipleObjects(handle_count, handles, FALSE, INFINITE);
 
-    HANDLE signaled_handle = NULL;
+    HANDLE signaled_handle = nullptr;
     if (wait_result >= WAIT_OBJECT_0 &&
         wait_result < WAIT_OBJECT_0 + handle_count) {
       signaled_handle = handles[wait_result - WAIT_OBJECT_0];
@@ -201,7 +201,7 @@ bool Subprocess::Communicate(const Message& input, Message* output,
     if (signaled_handle == child_stdin_) {
       DWORD n;
       if (!WriteFile(child_stdin_, input_data.data() + input_pos,
-                     input_data.size() - input_pos, &n, NULL)) {
+                     input_data.size() - input_pos, &n, nullptr)) {
         // Child closed pipe.  Presumably it will report an error later.
         // Pretend we're done for now.
         input_pos = input_data.size();
@@ -212,27 +212,27 @@ bool Subprocess::Communicate(const Message& input, Message* output,
       if (input_pos == input_data.size()) {
         // We're done writing.  Close.
         CloseHandleOrDie(child_stdin_);
-        child_stdin_ = NULL;
+        child_stdin_ = nullptr;
       }
     } else if (signaled_handle == child_stdout_) {
       char buffer[4096];
       DWORD n;
 
-      if (!ReadFile(child_stdout_, buffer, sizeof(buffer), &n, NULL)) {
+      if (!ReadFile(child_stdout_, buffer, sizeof(buffer), &n, nullptr)) {
         // We're done reading.  Close.
         CloseHandleOrDie(child_stdout_);
-        child_stdout_ = NULL;
+        child_stdout_ = nullptr;
       } else {
         output_data.append(buffer, n);
       }
     }
   }
 
-  if (child_stdin_ != NULL) {
+  if (child_stdin_ != nullptr) {
     // Child did not finish reading input before it closed the output.
     // Presumably it exited with an error.
     CloseHandleOrDie(child_stdin_);
-    child_stdin_ = NULL;
+    child_stdin_ = nullptr;
   }
 
   DWORD wait_result = WaitForSingleObject(child_handle_, INFINITE);
@@ -252,7 +252,7 @@ bool Subprocess::Communicate(const Message& input, Message* output,
   }
 
   CloseHandleOrDie(child_handle_);
-  child_handle_ = NULL;
+  child_handle_ = nullptr;
 
   if (exit_code != 0) {
     *error = strings::Substitute("Plugin failed with status code $0.", exit_code);
@@ -273,9 +273,10 @@ std::string Subprocess::Win32ErrorMessage(DWORD error_code) {
   // WTF?
   FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
                      FORMAT_MESSAGE_IGNORE_INSERTS,
-                 NULL, error_code, MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
+                 nullptr, error_code,
+                 MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
                  (LPSTR)&message,  // NOT A BUG!
-                 0, NULL);
+                 0, nullptr);
 
   std::string result = message;
   LocalFree(message);

src/google/protobuf/descriptor.cc

@@ -49,7 +49,6 @@
 
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/stubs/logging.h>
-#include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/any.h>
@@ -58,6 +57,7 @@
 #include <google/protobuf/io/tokenizer.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
 #include <google/protobuf/stubs/casts.h>
+#include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/stubs/substitute.h>
 #include <google/protobuf/descriptor_database.h>
 #include <google/protobuf/dynamic_message.h>
@@ -1300,10 +1300,6 @@ class FileDescriptorTables {
   bool AddFieldByNumber(FieldDescriptor* field);
   bool AddEnumValueByNumber(EnumValueDescriptor* value);
 
-  // Adds the field to the lowercase_name and camelcase_name maps.  Never
-  // fails because we allow duplicates; the first field by the name wins.
-  void AddFieldByStylizedNames(const FieldDescriptor* field);
-
   // Populates p->first->locations_by_path_ from p->second.
   // Unusual signature dictated by internal::call_once.
   static void BuildLocationsByPath(
@@ -1330,12 +1326,13 @@ class FileDescriptorTables {
   void FieldsByCamelcaseNamesLazyInitInternal() const;
 
   SymbolsByParentSet symbols_by_parent_;
-  mutable FieldsByNameMap fields_by_lowercase_name_;
-  std::unique_ptr<FieldsByNameMap> fields_by_lowercase_name_tmp_;
   mutable internal::once_flag fields_by_lowercase_name_once_;
-  mutable FieldsByNameMap fields_by_camelcase_name_;
-  std::unique_ptr<FieldsByNameMap> fields_by_camelcase_name_tmp_;
   mutable internal::once_flag fields_by_camelcase_name_once_;
+  // Make these fields atomic to avoid race conditions with
+  // GetEstimatedOwnedMemoryBytesSize. Once the pointer is set the map won't
+  // change anymore.
+  mutable std::atomic<const FieldsByNameMap*> fields_by_lowercase_name_{};
+  mutable std::atomic<const FieldsByNameMap*> fields_by_camelcase_name_{};
   FieldsByNumberSet fields_by_number_;  // Not including extensions.
   EnumValuesByNumberSet enum_values_by_number_;
   mutable EnumValuesByNumberSet unknown_enum_values_by_number_
@@ -1373,11 +1370,12 @@ DescriptorPool::Tables::Tables() {
 
 DescriptorPool::Tables::~Tables() { GOOGLE_DCHECK(checkpoints_.empty()); }
 
-FileDescriptorTables::FileDescriptorTables()
-    : fields_by_lowercase_name_tmp_(new FieldsByNameMap()),
-      fields_by_camelcase_name_tmp_(new FieldsByNameMap()) {}
+FileDescriptorTables::FileDescriptorTables() {}
 
-FileDescriptorTables::~FileDescriptorTables() {}
+FileDescriptorTables::~FileDescriptorTables() {
+  delete fields_by_lowercase_name_.load(std::memory_order_acquire);
+  delete fields_by_camelcase_name_.load(std::memory_order_acquire);
+}
 
 inline const FileDescriptorTables& FileDescriptorTables::GetEmptyInstance() {
   static auto file_descriptor_tables =
@@ -1520,13 +1518,14 @@ void FileDescriptorTables::FieldsByLowercaseNamesLazyInitStatic(
 }
 
 void FileDescriptorTables::FieldsByLowercaseNamesLazyInitInternal() const {
+  auto* map = new FieldsByNameMap;
   for (Symbol symbol : symbols_by_parent_) {
     const FieldDescriptor* field = symbol.field_descriptor();
     if (!field) continue;
-    PointerStringPair lowercase_key(FindParentForFieldsByMap(field),
-                                    field->lowercase_name().c_str());
-    InsertIfNotPresent(&fields_by_lowercase_name_, lowercase_key, field);
+    (*map)[{FindParentForFieldsByMap(field), field->lowercase_name().c_str()}] =
+        field;
   }
+  fields_by_lowercase_name_.store(map, std::memory_order_release);
 }
 
 inline const FieldDescriptor* FileDescriptorTables::FindFieldByLowercaseName(
@@ -1534,8 +1533,9 @@ inline const FieldDescriptor* FileDescriptorTables::FindFieldByLowercaseName(
   internal::call_once(
       fields_by_lowercase_name_once_,
       &FileDescriptorTables::FieldsByLowercaseNamesLazyInitStatic, this);
-  return FindPtrOrNull(fields_by_lowercase_name_,
-                            PointerStringPair(parent, lowercase_name));
+  return FindPtrOrNull(
+      *fields_by_lowercase_name_.load(std::memory_order_acquire),
+      PointerStringPair(parent, lowercase_name));
 }
 
 void FileDescriptorTables::FieldsByCamelcaseNamesLazyInitStatic(
@@ -1544,13 +1544,14 @@ void FileDescriptorTables::FieldsByCamelcaseNamesLazyInitStatic(
 }
 
 void FileDescriptorTables::FieldsByCamelcaseNamesLazyInitInternal() const {
+  auto* map = new FieldsByNameMap;
   for (Symbol symbol : symbols_by_parent_) {
     const FieldDescriptor* field = symbol.field_descriptor();
     if (!field) continue;
-    PointerStringPair camelcase_key(FindParentForFieldsByMap(field),
-                                    field->camelcase_name().c_str());
-    InsertIfNotPresent(&fields_by_camelcase_name_, camelcase_key, field);
+    (*map)[{FindParentForFieldsByMap(field), field->camelcase_name().c_str()}] =
+        field;
   }
+  fields_by_camelcase_name_.store(map, std::memory_order_release);
 }
 
 inline const FieldDescriptor* FileDescriptorTables::FindFieldByCamelcaseName(
@@ -1558,8 +1559,9 @@ inline const FieldDescriptor* FileDescriptorTables::FindFieldByCamelcaseName(
   internal::call_once(
       fields_by_camelcase_name_once_,
       FileDescriptorTables::FieldsByCamelcaseNamesLazyInitStatic, this);
-  return FindPtrOrNull(fields_by_camelcase_name_,
-                            PointerStringPair(parent, camelcase_name));
+  return FindPtrOrNull(
+      *fields_by_camelcase_name_.load(std::memory_order_acquire),
+      PointerStringPair(parent, camelcase_name));
 }
 
 inline const EnumValueDescriptor* FileDescriptorTables::FindEnumValueByNumber(
@@ -1619,8 +1621,8 @@ FileDescriptorTables::FindEnumValueByNumberCreatingIfUnknown(
     // EnumDescriptor (it's not a part of the enum as originally defined), but
     // we do insert it into the table so that we can return the same pointer
     // later.
-    std::string enum_value_name = StringPrintf("UNKNOWN_ENUM_VALUE_%s_%d",
-                                               parent->name().c_str(), number);
+    std::string enum_value_name = StringPrintf(
+        "UNKNOWN_ENUM_VALUE_%s_%d", parent->name().c_str(), number);
     auto* pool = DescriptorPool::generated_pool();
     auto* tables = const_cast<DescriptorPool::Tables*>(pool->tables_.get());
     internal::FlatAllocator alloc;
@@ -1689,39 +1691,7 @@ bool DescriptorPool::Tables::AddFile(const FileDescriptor* file) {
   }
 }
 
-void FileDescriptorTables::FinalizeTables() {
-  // Clean up the temporary maps used by AddFieldByStylizedNames().
-  fields_by_lowercase_name_tmp_ = nullptr;
-  fields_by_camelcase_name_tmp_ = nullptr;
-}
-
-void FileDescriptorTables::AddFieldByStylizedNames(
-    const FieldDescriptor* field) {
-  const void* parent = FindParentForFieldsByMap(field);
-
-  // We want fields_by_{lower,camel}case_name_ to be lazily built, but
-  // cross-link order determines which entry will be present in the case of a
-  // conflict. So we use the temporary maps that get destroyed after
-  // BuildFileImpl() to detect the conflicts, and only store the conflicts in
-  // the map that will persist. We will then lazily populate the rest of the
-  // entries from fields_by_number_.
-
-  PointerStringPair lowercase_key(parent, field->lowercase_name().c_str());
-  if (!InsertIfNotPresent(fields_by_lowercase_name_tmp_.get(),
-                               lowercase_key, field)) {
-    InsertIfNotPresent(
-        &fields_by_lowercase_name_, lowercase_key,
-        FindPtrOrNull(*fields_by_lowercase_name_tmp_, lowercase_key));
-  }
-
-  PointerStringPair camelcase_key(parent, field->camelcase_name().c_str());
-  if (!InsertIfNotPresent(fields_by_camelcase_name_tmp_.get(),
-                               camelcase_key, field)) {
-    InsertIfNotPresent(
-        &fields_by_camelcase_name_, camelcase_key,
-        FindPtrOrNull(*fields_by_camelcase_name_tmp_, camelcase_key));
-  }
-}
+void FileDescriptorTables::FinalizeTables() {}
 
 bool FileDescriptorTables::AddFieldByNumber(FieldDescriptor* field) {
   // Skip fields that are at the start of the sequence.
@@ -6271,9 +6241,6 @@ void DescriptorBuilder::CrossLinkField(FieldDescriptor* field,
     field->options_ = &FieldOptions::default_instance();
   }
 
-  // Add the field to the lowercase-name and camelcase-name tables.
-  file_tables_->AddFieldByStylizedNames(field);
-
   if (proto.has_extendee()) {
     Symbol extendee =
         LookupSymbol(proto.extendee(), field->full_name(),

src/google/protobuf/descriptor.pb.cc

@@ -1506,26 +1506,26 @@ FileDescriptorProto::FileDescriptorProto(const FileDescriptorProto& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   package_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    package_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_package()) {
-    package_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_package(), 
+    package_.Set(from._internal_package(), 
       GetArenaForAllocation());
   }
   syntax_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    syntax_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    syntax_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_syntax()) {
-    syntax_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_syntax(), 
+    syntax_.Set(from._internal_syntax(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -1544,15 +1544,15 @@ FileDescriptorProto::FileDescriptorProto(const FileDescriptorProto& from)
 inline void FileDescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 package_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  package_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 syntax_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  syntax_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  syntax_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&options_) - reinterpret_cast<char*>(this)),
@@ -1571,9 +1571,9 @@ FileDescriptorProto::~FileDescriptorProto() {
 
 inline void FileDescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  package_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  syntax_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  package_.Destroy();
+  syntax_.Destroy();
   if (this != internal_default_instance()) delete options_;
   if (this != internal_default_instance()) delete source_code_info_;
 }
@@ -2102,17 +2102,14 @@ void FileDescriptorProto::InternalSwap(FileDescriptorProto* other) {
   public_dependency_.InternalSwap(&other->public_dependency_);
   weak_dependency_.InternalSwap(&other->weak_dependency_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &package_, lhs_arena,
       &other->package_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &syntax_, lhs_arena,
       &other->syntax_, rhs_arena
   );
@@ -2682,10 +2679,10 @@ DescriptorProto::DescriptorProto(const DescriptorProto& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -2699,7 +2696,7 @@ DescriptorProto::DescriptorProto(const DescriptorProto& from)
 inline void DescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 options_ = nullptr;
 }
@@ -2715,7 +2712,7 @@ DescriptorProto::~DescriptorProto() {
 
 inline void DescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete options_;
 }
 
@@ -3173,7 +3170,6 @@ void DescriptorProto::InternalSwap(DescriptorProto* other) {
   reserved_range_.InternalSwap(&other->reserved_range_);
   reserved_name_.InternalSwap(&other->reserved_name_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -3443,42 +3439,42 @@ FieldDescriptorProto::FieldDescriptorProto(const FieldDescriptorProto& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   extendee_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    extendee_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    extendee_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_extendee()) {
-    extendee_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_extendee(), 
+    extendee_.Set(from._internal_extendee(), 
       GetArenaForAllocation());
   }
   type_name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    type_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    type_name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_type_name()) {
-    type_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_type_name(), 
+    type_name_.Set(from._internal_type_name(), 
       GetArenaForAllocation());
   }
   default_value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    default_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    default_value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_default_value()) {
-    default_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_default_value(), 
+    default_value_.Set(from._internal_default_value(), 
       GetArenaForAllocation());
   }
   json_name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    json_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    json_name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_json_name()) {
-    json_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_json_name(), 
+    json_name_.Set(from._internal_json_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -3495,23 +3491,23 @@ FieldDescriptorProto::FieldDescriptorProto(const FieldDescriptorProto& from)
 inline void FieldDescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 extendee_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  extendee_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  extendee_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 type_name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  type_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  type_name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 default_value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  default_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  default_value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 json_name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  json_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  json_name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&options_) - reinterpret_cast<char*>(this)),
@@ -3532,11 +3528,11 @@ FieldDescriptorProto::~FieldDescriptorProto() {
 
 inline void FieldDescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  extendee_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  type_name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  default_value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  json_name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  extendee_.Destroy();
+  type_name_.Destroy();
+  default_value_.Destroy();
+  json_name_.Destroy();
   if (this != internal_default_instance()) delete options_;
 }
 
@@ -4010,27 +4006,22 @@ void FieldDescriptorProto::InternalSwap(FieldDescriptorProto* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_has_bits_[0], other->_has_bits_[0]);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &extendee_, lhs_arena,
       &other->extendee_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &type_name_, lhs_arena,
       &other->type_name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &default_value_, lhs_arena,
       &other->default_value_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &json_name_, lhs_arena,
       &other->json_name_, rhs_arena
   );
@@ -4080,10 +4071,10 @@ OneofDescriptorProto::OneofDescriptorProto(const OneofDescriptorProto& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -4097,7 +4088,7 @@ OneofDescriptorProto::OneofDescriptorProto(const OneofDescriptorProto& from)
 inline void OneofDescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 options_ = nullptr;
 }
@@ -4113,7 +4104,7 @@ OneofDescriptorProto::~OneofDescriptorProto() {
 
 inline void OneofDescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete options_;
 }
 
@@ -4304,7 +4295,6 @@ void OneofDescriptorProto::InternalSwap(OneofDescriptorProto* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_has_bits_[0], other->_has_bits_[0]);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -4583,10 +4573,10 @@ EnumDescriptorProto::EnumDescriptorProto(const EnumDescriptorProto& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -4600,7 +4590,7 @@ EnumDescriptorProto::EnumDescriptorProto(const EnumDescriptorProto& from)
 inline void EnumDescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 options_ = nullptr;
 }
@@ -4616,7 +4606,7 @@ EnumDescriptorProto::~EnumDescriptorProto() {
 
 inline void EnumDescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete options_;
 }
 
@@ -4909,7 +4899,6 @@ void EnumDescriptorProto::InternalSwap(EnumDescriptorProto* other) {
   reserved_range_.InternalSwap(&other->reserved_range_);
   reserved_name_.InternalSwap(&other->reserved_name_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -4955,10 +4944,10 @@ EnumValueDescriptorProto::EnumValueDescriptorProto(const EnumValueDescriptorProt
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -4973,7 +4962,7 @@ EnumValueDescriptorProto::EnumValueDescriptorProto(const EnumValueDescriptorProt
 inline void EnumValueDescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&options_) - reinterpret_cast<char*>(this)),
@@ -4992,7 +4981,7 @@ EnumValueDescriptorProto::~EnumValueDescriptorProto() {
 
 inline void EnumValueDescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete options_;
 }
 
@@ -5208,7 +5197,6 @@ void EnumValueDescriptorProto::InternalSwap(EnumValueDescriptorProto* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_has_bits_[0], other->_has_bits_[0]);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -5258,10 +5246,10 @@ ServiceDescriptorProto::ServiceDescriptorProto(const ServiceDescriptorProto& fro
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -5275,7 +5263,7 @@ ServiceDescriptorProto::ServiceDescriptorProto(const ServiceDescriptorProto& fro
 inline void ServiceDescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 options_ = nullptr;
 }
@@ -5291,7 +5279,7 @@ ServiceDescriptorProto::~ServiceDescriptorProto() {
 
 inline void ServiceDescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete options_;
 }
 
@@ -5515,7 +5503,6 @@ void ServiceDescriptorProto::InternalSwap(ServiceDescriptorProto* other) {
   swap(_has_bits_[0], other->_has_bits_[0]);
   method_.InternalSwap(&other->method_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -5570,26 +5557,26 @@ MethodDescriptorProto::MethodDescriptorProto(const MethodDescriptorProto& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   input_type_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    input_type_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    input_type_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_input_type()) {
-    input_type_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_input_type(), 
+    input_type_.Set(from._internal_input_type(), 
       GetArenaForAllocation());
   }
   output_type_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    output_type_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    output_type_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_output_type()) {
-    output_type_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_output_type(), 
+    output_type_.Set(from._internal_output_type(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_options()) {
@@ -5606,15 +5593,15 @@ MethodDescriptorProto::MethodDescriptorProto(const MethodDescriptorProto& from)
 inline void MethodDescriptorProto::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 input_type_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  input_type_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  input_type_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 output_type_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  output_type_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  output_type_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&options_) - reinterpret_cast<char*>(this)),
@@ -5633,9 +5620,9 @@ MethodDescriptorProto::~MethodDescriptorProto() {
 
 inline void MethodDescriptorProto::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  input_type_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  output_type_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  input_type_.Destroy();
+  output_type_.Destroy();
   if (this != internal_default_instance()) delete options_;
 }
 
@@ -5946,17 +5933,14 @@ void MethodDescriptorProto::InternalSwap(MethodDescriptorProto* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_has_bits_[0], other->_has_bits_[0]);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &input_type_, lhs_arena,
       &other->input_type_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &output_type_, lhs_arena,
       &other->output_type_, rhs_arena
   );
@@ -6057,82 +6041,82 @@ FileOptions::FileOptions(const FileOptions& from)
   _extensions_.MergeFrom(internal_default_instance(), from._extensions_);
   java_package_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    java_package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    java_package_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_java_package()) {
-    java_package_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_java_package(), 
+    java_package_.Set(from._internal_java_package(), 
       GetArenaForAllocation());
   }
   java_outer_classname_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    java_outer_classname_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    java_outer_classname_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_java_outer_classname()) {
-    java_outer_classname_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_java_outer_classname(), 
+    java_outer_classname_.Set(from._internal_java_outer_classname(), 
       GetArenaForAllocation());
   }
   go_package_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    go_package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    go_package_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_go_package()) {
-    go_package_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_go_package(), 
+    go_package_.Set(from._internal_go_package(), 
       GetArenaForAllocation());
   }
   objc_class_prefix_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    objc_class_prefix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    objc_class_prefix_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_objc_class_prefix()) {
-    objc_class_prefix_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_objc_class_prefix(), 
+    objc_class_prefix_.Set(from._internal_objc_class_prefix(), 
       GetArenaForAllocation());
   }
   csharp_namespace_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    csharp_namespace_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    csharp_namespace_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_csharp_namespace()) {
-    csharp_namespace_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_csharp_namespace(), 
+    csharp_namespace_.Set(from._internal_csharp_namespace(), 
       GetArenaForAllocation());
   }
   swift_prefix_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    swift_prefix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    swift_prefix_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_swift_prefix()) {
-    swift_prefix_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_swift_prefix(), 
+    swift_prefix_.Set(from._internal_swift_prefix(), 
       GetArenaForAllocation());
   }
   php_class_prefix_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    php_class_prefix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    php_class_prefix_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_php_class_prefix()) {
-    php_class_prefix_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_php_class_prefix(), 
+    php_class_prefix_.Set(from._internal_php_class_prefix(), 
       GetArenaForAllocation());
   }
   php_namespace_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    php_namespace_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    php_namespace_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_php_namespace()) {
-    php_namespace_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_php_namespace(), 
+    php_namespace_.Set(from._internal_php_namespace(), 
       GetArenaForAllocation());
   }
   php_metadata_namespace_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    php_metadata_namespace_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    php_metadata_namespace_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_php_metadata_namespace()) {
-    php_metadata_namespace_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_php_metadata_namespace(), 
+    php_metadata_namespace_.Set(from._internal_php_metadata_namespace(), 
       GetArenaForAllocation());
   }
   ruby_package_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    ruby_package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    ruby_package_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_ruby_package()) {
-    ruby_package_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_ruby_package(), 
+    ruby_package_.Set(from._internal_ruby_package(), 
       GetArenaForAllocation());
   }
   ::memcpy(&java_multiple_files_, &from.java_multiple_files_,
@@ -6144,43 +6128,43 @@ FileOptions::FileOptions(const FileOptions& from)
 inline void FileOptions::SharedCtor() {
 java_package_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  java_package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  java_package_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 java_outer_classname_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  java_outer_classname_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  java_outer_classname_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 go_package_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  go_package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  go_package_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 objc_class_prefix_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  objc_class_prefix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  objc_class_prefix_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 csharp_namespace_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  csharp_namespace_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  csharp_namespace_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 swift_prefix_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  swift_prefix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  swift_prefix_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 php_class_prefix_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  php_class_prefix_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  php_class_prefix_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 php_namespace_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  php_namespace_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  php_namespace_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 php_metadata_namespace_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  php_metadata_namespace_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  php_metadata_namespace_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ruby_package_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  ruby_package_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  ruby_package_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&java_multiple_files_) - reinterpret_cast<char*>(this)),
@@ -6201,16 +6185,16 @@ FileOptions::~FileOptions() {
 
 inline void FileOptions::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  java_package_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  java_outer_classname_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  go_package_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  objc_class_prefix_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  csharp_namespace_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  swift_prefix_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  php_class_prefix_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  php_namespace_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  php_metadata_namespace_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  ruby_package_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  java_package_.Destroy();
+  java_outer_classname_.Destroy();
+  go_package_.Destroy();
+  objc_class_prefix_.Destroy();
+  csharp_namespace_.Destroy();
+  swift_prefix_.Destroy();
+  php_class_prefix_.Destroy();
+  php_namespace_.Destroy();
+  php_metadata_namespace_.Destroy();
+  ruby_package_.Destroy();
 }
 
 void FileOptions::SetCachedSize(int size) const {
@@ -6994,52 +6978,42 @@ void FileOptions::InternalSwap(FileOptions* other) {
   swap(_has_bits_[0], other->_has_bits_[0]);
   uninterpreted_option_.InternalSwap(&other->uninterpreted_option_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &java_package_, lhs_arena,
       &other->java_package_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &java_outer_classname_, lhs_arena,
       &other->java_outer_classname_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &go_package_, lhs_arena,
       &other->go_package_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &objc_class_prefix_, lhs_arena,
       &other->objc_class_prefix_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &csharp_namespace_, lhs_arena,
       &other->csharp_namespace_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &swift_prefix_, lhs_arena,
       &other->swift_prefix_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &php_class_prefix_, lhs_arena,
       &other->php_class_prefix_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &php_namespace_, lhs_arena,
       &other->php_namespace_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &php_metadata_namespace_, lhs_arena,
       &other->php_metadata_namespace_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &ruby_package_, lhs_arena,
       &other->ruby_package_, rhs_arena
   );
@@ -9097,10 +9071,10 @@ UninterpretedOption_NamePart::UninterpretedOption_NamePart(const UninterpretedOp
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_part_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_part_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_part_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_name_part()) {
-    name_part_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name_part(), 
+    name_part_.Set(from._internal_name_part(), 
       GetArenaForAllocation());
   }
   is_extension_ = from.is_extension_;
@@ -9110,7 +9084,7 @@ UninterpretedOption_NamePart::UninterpretedOption_NamePart(const UninterpretedOp
 inline void UninterpretedOption_NamePart::SharedCtor() {
 name_part_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_part_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_part_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 is_extension_ = false;
 }
@@ -9126,7 +9100,7 @@ UninterpretedOption_NamePart::~UninterpretedOption_NamePart() {
 
 inline void UninterpretedOption_NamePart::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_part_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_part_.Destroy();
 }
 
 void UninterpretedOption_NamePart::SetCachedSize(int size) const {
@@ -9323,7 +9297,6 @@ void UninterpretedOption_NamePart::InternalSwap(UninterpretedOption_NamePart* ot
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_has_bits_[0], other->_has_bits_[0]);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_part_, lhs_arena,
       &other->name_part_, rhs_arena
   );
@@ -9375,26 +9348,26 @@ UninterpretedOption::UninterpretedOption(const UninterpretedOption& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   identifier_value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    identifier_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    identifier_value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_identifier_value()) {
-    identifier_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_identifier_value(), 
+    identifier_value_.Set(from._internal_identifier_value(), 
       GetArenaForAllocation());
   }
   string_value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    string_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    string_value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_string_value()) {
-    string_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_string_value(), 
+    string_value_.Set(from._internal_string_value(), 
       GetArenaForAllocation());
   }
   aggregate_value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    aggregate_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    aggregate_value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_aggregate_value()) {
-    aggregate_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_aggregate_value(), 
+    aggregate_value_.Set(from._internal_aggregate_value(), 
       GetArenaForAllocation());
   }
   ::memcpy(&positive_int_value_, &from.positive_int_value_,
@@ -9406,15 +9379,15 @@ UninterpretedOption::UninterpretedOption(const UninterpretedOption& from)
 inline void UninterpretedOption::SharedCtor() {
 identifier_value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  identifier_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  identifier_value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 string_value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  string_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  string_value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 aggregate_value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  aggregate_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  aggregate_value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&positive_int_value_) - reinterpret_cast<char*>(this)),
@@ -9433,9 +9406,9 @@ UninterpretedOption::~UninterpretedOption() {
 
 inline void UninterpretedOption::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  identifier_value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  string_value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  aggregate_value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  identifier_value_.Destroy();
+  string_value_.Destroy();
+  aggregate_value_.Destroy();
 }
 
 void UninterpretedOption::SetCachedSize(int size) const {
@@ -9764,17 +9737,14 @@ void UninterpretedOption::InternalSwap(UninterpretedOption* other) {
   swap(_has_bits_[0], other->_has_bits_[0]);
   name_.InternalSwap(&other->name_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &identifier_value_, lhs_arena,
       &other->identifier_value_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &string_value_, lhs_arena,
       &other->string_value_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &aggregate_value_, lhs_arena,
       &other->aggregate_value_, rhs_arena
   );
@@ -9823,18 +9793,18 @@ SourceCodeInfo_Location::SourceCodeInfo_Location(const SourceCodeInfo_Location&
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   leading_comments_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    leading_comments_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    leading_comments_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_leading_comments()) {
-    leading_comments_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_leading_comments(), 
+    leading_comments_.Set(from._internal_leading_comments(), 
       GetArenaForAllocation());
   }
   trailing_comments_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    trailing_comments_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    trailing_comments_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_trailing_comments()) {
-    trailing_comments_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_trailing_comments(), 
+    trailing_comments_.Set(from._internal_trailing_comments(), 
       GetArenaForAllocation());
   }
   // @@protoc_insertion_point(copy_constructor:google.protobuf.SourceCodeInfo.Location)
@@ -9843,11 +9813,11 @@ SourceCodeInfo_Location::SourceCodeInfo_Location(const SourceCodeInfo_Location&
 inline void SourceCodeInfo_Location::SharedCtor() {
 leading_comments_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  leading_comments_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  leading_comments_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 trailing_comments_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  trailing_comments_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  trailing_comments_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 }
 
@@ -9862,8 +9832,8 @@ SourceCodeInfo_Location::~SourceCodeInfo_Location() {
 
 inline void SourceCodeInfo_Location::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  leading_comments_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  trailing_comments_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  leading_comments_.Destroy();
+  trailing_comments_.Destroy();
 }
 
 void SourceCodeInfo_Location::SetCachedSize(int size) const {
@@ -10168,12 +10138,10 @@ void SourceCodeInfo_Location::InternalSwap(SourceCodeInfo_Location* other) {
   span_.InternalSwap(&other->span_);
   leading_detached_comments_.InternalSwap(&other->leading_detached_comments_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &leading_comments_, lhs_arena,
       &other->leading_comments_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &trailing_comments_, lhs_arena,
       &other->trailing_comments_, rhs_arena
   );
@@ -10393,10 +10361,10 @@ GeneratedCodeInfo_Annotation::GeneratedCodeInfo_Annotation(const GeneratedCodeIn
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   source_file_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    source_file_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    source_file_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (from._internal_has_source_file()) {
-    source_file_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_source_file(), 
+    source_file_.Set(from._internal_source_file(), 
       GetArenaForAllocation());
   }
   ::memcpy(&begin_, &from.begin_,
@@ -10408,7 +10376,7 @@ GeneratedCodeInfo_Annotation::GeneratedCodeInfo_Annotation(const GeneratedCodeIn
 inline void GeneratedCodeInfo_Annotation::SharedCtor() {
 source_file_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  source_file_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  source_file_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&begin_) - reinterpret_cast<char*>(this)),
@@ -10427,7 +10395,7 @@ GeneratedCodeInfo_Annotation::~GeneratedCodeInfo_Annotation() {
 
 inline void GeneratedCodeInfo_Annotation::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  source_file_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  source_file_.Destroy();
 }
 
 void GeneratedCodeInfo_Annotation::SetCachedSize(int size) const {
@@ -10672,7 +10640,6 @@ void GeneratedCodeInfo_Annotation::InternalSwap(GeneratedCodeInfo_Annotation* ot
   swap(_has_bits_[0], other->_has_bits_[0]);
   path_.InternalSwap(&other->path_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &source_file_, lhs_arena,
       &other->source_file_, rhs_arena
   );

src/google/protobuf/descriptor_unittest.cc

@@ -66,6 +66,8 @@
 // Must be included last.
 #include <google/protobuf/port_def.inc>
 
+using ::testing::AnyOf;
+
 namespace google {
 namespace protobuf {
 
@@ -1307,7 +1309,8 @@ TEST_F(StylizedFieldNamesTest, CamelcaseName) {
 
 TEST_F(StylizedFieldNamesTest, FindByLowercaseName) {
   EXPECT_EQ(message_->field(0), message_->FindFieldByLowercaseName("foo_foo"));
-  EXPECT_EQ(message_->field(1), message_->FindFieldByLowercaseName("foobar"));
+  EXPECT_THAT(message_->FindFieldByLowercaseName("foobar"),
+              AnyOf(message_->field(1), message_->field(4)));
   EXPECT_EQ(message_->field(2), message_->FindFieldByLowercaseName("foobaz"));
   EXPECT_TRUE(message_->FindFieldByLowercaseName("FooBar") == nullptr);
   EXPECT_TRUE(message_->FindFieldByLowercaseName("fooBaz") == nullptr);
@@ -1316,8 +1319,8 @@ TEST_F(StylizedFieldNamesTest, FindByLowercaseName) {
 
   EXPECT_EQ(message_->extension(0),
             message_->FindExtensionByLowercaseName("bar_foo"));
-  EXPECT_EQ(message_->extension(1),
-            message_->FindExtensionByLowercaseName("barbar"));
+  EXPECT_THAT(message_->FindExtensionByLowercaseName("barbar"),
+              AnyOf(message_->extension(1), message_->extension(4)));
   EXPECT_EQ(message_->extension(2),
             message_->FindExtensionByLowercaseName("barbaz"));
   EXPECT_TRUE(message_->FindExtensionByLowercaseName("BarBar") == nullptr);
@@ -1327,7 +1330,8 @@ TEST_F(StylizedFieldNamesTest, FindByLowercaseName) {
 
   EXPECT_EQ(file_->extension(0),
             file_->FindExtensionByLowercaseName("baz_foo"));
-  EXPECT_EQ(file_->extension(1), file_->FindExtensionByLowercaseName("bazbar"));
+  EXPECT_THAT(file_->FindExtensionByLowercaseName("bazbar"),
+              AnyOf(file_->extension(1), file_->extension(4)));
   EXPECT_EQ(file_->extension(2), file_->FindExtensionByLowercaseName("bazbaz"));
   EXPECT_TRUE(file_->FindExtensionByLowercaseName("BazBar") == nullptr);
   EXPECT_TRUE(file_->FindExtensionByLowercaseName("bazBaz") == nullptr);
@@ -1335,7 +1339,8 @@ TEST_F(StylizedFieldNamesTest, FindByLowercaseName) {
 }
 
 TEST_F(StylizedFieldNamesTest, FindByCamelcaseName) {
-  EXPECT_EQ(message_->field(0), message_->FindFieldByCamelcaseName("fooFoo"));
+  EXPECT_THAT(message_->FindFieldByCamelcaseName("fooFoo"),
+              AnyOf(message_->field(0), message_->field(3)));
   EXPECT_EQ(message_->field(1), message_->FindFieldByCamelcaseName("fooBar"));
   EXPECT_EQ(message_->field(2), message_->FindFieldByCamelcaseName("fooBaz"));
   EXPECT_TRUE(message_->FindFieldByCamelcaseName("foo_foo") == nullptr);
@@ -1343,8 +1348,8 @@ TEST_F(StylizedFieldNamesTest, FindByCamelcaseName) {
   EXPECT_TRUE(message_->FindFieldByCamelcaseName("barFoo") == nullptr);
   EXPECT_TRUE(message_->FindFieldByCamelcaseName("nosuchfield") == nullptr);
 
-  EXPECT_EQ(message_->extension(0),
-            message_->FindExtensionByCamelcaseName("barFoo"));
+  EXPECT_THAT(message_->FindExtensionByCamelcaseName("barFoo"),
+              AnyOf(message_->extension(0), message_->extension(3)));
   EXPECT_EQ(message_->extension(1),
             message_->FindExtensionByCamelcaseName("barBar"));
   EXPECT_EQ(message_->extension(2),
@@ -1354,7 +1359,8 @@ TEST_F(StylizedFieldNamesTest, FindByCamelcaseName) {
   EXPECT_TRUE(message_->FindExtensionByCamelcaseName("fooFoo") == nullptr);
   EXPECT_TRUE(message_->FindExtensionByCamelcaseName("nosuchfield") == nullptr);
 
-  EXPECT_EQ(file_->extension(0), file_->FindExtensionByCamelcaseName("bazFoo"));
+  EXPECT_THAT(file_->FindExtensionByCamelcaseName("bazFoo"),
+              AnyOf(file_->extension(0), file_->extension(3)));
   EXPECT_EQ(file_->extension(1), file_->FindExtensionByCamelcaseName("bazBar"));
   EXPECT_EQ(file_->extension(2), file_->FindExtensionByCamelcaseName("bazBaz"));
   EXPECT_TRUE(file_->FindExtensionByCamelcaseName("baz_foo") == nullptr);

src/google/protobuf/dynamic_message.cc

@@ -417,11 +417,7 @@ void DynamicMessage::SharedCtor(bool lock_factory) {
           case FieldOptions::STRING:
             if (!field->is_repeated()) {
               ArenaStringPtr* asp = new (field_ptr) ArenaStringPtr();
-              if (field->default_value_string().empty()) {
-                asp->InitDefault();
-              } else {
-                asp->InitDefault(nullptr);
-              }
+              asp->InitDefault();
             } else {
               new (field_ptr)
                   RepeatedPtrField<std::string>(GetArenaForAllocation());
@@ -522,13 +518,7 @@ DynamicMessage::~DynamicMessage() {
           switch (field->options().ctype()) {
             default:
             case FieldOptions::STRING: {
-              // Oneof string fields are never set as a default instance.
-              // We just need to pass some arbitrary default string to make it
-              // work. This allows us to not have the real default accessible
-              // from reflection.
-              const std::string* default_value = nullptr;
-              reinterpret_cast<ArenaStringPtr*>(field_ptr)->Destroy(
-                  default_value, nullptr);
+              reinterpret_cast<ArenaStringPtr*>(field_ptr)->Destroy();
               break;
             }
           }
@@ -582,13 +572,7 @@ DynamicMessage::~DynamicMessage() {
       switch (field->options().ctype()) {
         default:  // TODO(kenton):  Support other string reps.
         case FieldOptions::STRING: {
-          const std::string* default_value =
-              reinterpret_cast<const ArenaStringPtr*>(
-                  type_info_->prototype->OffsetToPointer(
-                      type_info_->offsets[i]))
-                  ->GetPointer();
-          reinterpret_cast<ArenaStringPtr*>(field_ptr)->Destroy(default_value,
-                                                                nullptr);
+          reinterpret_cast<ArenaStringPtr*>(field_ptr)->Destroy();
           break;
         }
       }

src/google/protobuf/generated_message_reflection.cc

@@ -280,10 +280,9 @@ size_t Reflection::SpaceUsedLong(const Message& message) const {
   total_size += GetUnknownFields(message).SpaceUsedExcludingSelfLong();
 
   // If this message owns an arena, add any unused space that's been allocated.
-  auto* arena = Arena::InternalHelper<Message>::GetArenaForAllocation(&message);
-  if (arena != nullptr &&
-      Arena::InternalHelper<Message>::GetOwningArena(&message) == nullptr &&
-      Arena::InternalHelper<Message>::IsMessageOwnedArena(arena)) {
+  auto* arena = Arena::InternalGetArenaForAllocation(&message);
+  if (arena != nullptr && Arena::InternalGetOwningArena(&message) == nullptr &&
+      arena->InternalIsMessageOwnedArena()) {
     total_size += arena->SpaceAllocated() - arena->SpaceUsed();
   }
 
@@ -354,31 +353,26 @@ size_t Reflection::SpaceUsedLong(const Message& message) const {
         case FieldDescriptor::CPPTYPE_STRING: {
           switch (field->options().ctype()) {
             default:  // TODO(kenton):  Support other string reps.
-            case FieldOptions::STRING: {
+            case FieldOptions::STRING:
               if (IsInlined(field)) {
                 const std::string* ptr =
                     &GetField<InlinedStringField>(message, field).GetNoArena();
                 total_size += StringSpaceUsedExcludingSelfLong(*ptr);
-                break;
-              }
-
-              const std::string* ptr =
-                  GetField<ArenaStringPtr>(message, field).GetPointer();
-
-              // Initially, the string points to the default value stored
-              // in the prototype. Only count the string if it has been
-              // changed from the default value.
-              // Except oneof fields, those never point to a default instance,
-              // and there is no default instance to point to.
-              if (schema_.InRealOneof(field) ||
-                  ptr != DefaultRaw<ArenaStringPtr>(field).GetPointer()) {
-                // string fields are represented by just a pointer, so also
-                // include sizeof(string) as well.
-                total_size +=
-                    sizeof(*ptr) + StringSpaceUsedExcludingSelfLong(*ptr);
+              } else {
+                // Initially, the string points to the default value stored
+                // in the prototype. Only count the string if it has been
+                // changed from the default value.
+                // Except oneof fields, those never point to a default instance,
+                // and there is no default instance to point to.
+                const auto& str = GetField<ArenaStringPtr>(message, field);
+                if (!str.IsDefault() || schema_.InRealOneof(field)) {
+                  // string fields are represented by just a pointer, so also
+                  // include sizeof(string) as well.
+                  total_size += sizeof(std::string) +
+                                StringSpaceUsedExcludingSelfLong(str.Get());
+                }
               }
               break;
-            }
           }
           break;
         }
@@ -486,8 +480,7 @@ class SwapFieldHelper {
   static void SwapStringField(const Reflection* r, Message* lhs, Message* rhs,
                               const FieldDescriptor* field);
 
-  static void SwapArenaStringPtr(const std::string* default_ptr,
-                                 ArenaStringPtr* lhs, Arena* lhs_arena,
+  static void SwapArenaStringPtr(ArenaStringPtr* lhs, Arena* lhs_arena,
                                  ArenaStringPtr* rhs, Arena* rhs_arena);
 
   template <bool unsafe_shallow_swap>
@@ -551,12 +544,11 @@ void SwapFieldHelper::SwapInlinedStrings(const Reflection* r, Message* lhs,
                                      rhs_arena, rhs_arena_dtor_registered, rhs);
   } else {
     const std::string temp = lhs_string->Get();
-    lhs_string->Set(nullptr, rhs_string->Get(), lhs_arena,
+    lhs_string->Set(rhs_string->Get(), lhs_arena,
                     r->IsInlinedStringDonated(*lhs, field), lhs_state, mask,
                     lhs);
-    rhs_string->Set(nullptr, temp, rhs_arena,
-                    r->IsInlinedStringDonated(*rhs, field), rhs_state, mask,
-                    rhs);
+    rhs_string->Set(temp, rhs_arena, r->IsInlinedStringDonated(*rhs, field),
+                    rhs_state, mask, rhs);
   }
 }
 
@@ -570,8 +562,7 @@ void SwapFieldHelper::SwapNonInlinedStrings(const Reflection* r, Message* lhs,
     ArenaStringPtr::UnsafeShallowSwap(lhs_string, rhs_string);
   } else {
     SwapFieldHelper::SwapArenaStringPtr(
-        r->DefaultRaw<ArenaStringPtr>(field).GetPointer(),  //
-        lhs_string, lhs->GetArenaForAllocation(),           //
+        lhs_string, lhs->GetArenaForAllocation(),  //
         rhs_string, rhs->GetArenaForAllocation());
   }
 }
@@ -595,28 +586,27 @@ void SwapFieldHelper::SwapStringField(const Reflection* r, Message* lhs,
   }
 }
 
-void SwapFieldHelper::SwapArenaStringPtr(const std::string* default_ptr,
-                                         ArenaStringPtr* lhs, Arena* lhs_arena,
+void SwapFieldHelper::SwapArenaStringPtr(ArenaStringPtr* lhs, Arena* lhs_arena,
                                          ArenaStringPtr* rhs,
                                          Arena* rhs_arena) {
   if (lhs_arena == rhs_arena) {
-    ArenaStringPtr::InternalSwap(default_ptr, lhs, lhs_arena, rhs, rhs_arena);
+    ArenaStringPtr::InternalSwap(lhs, lhs_arena, rhs, rhs_arena);
   } else if (lhs->IsDefault() && rhs->IsDefault()) {
     // Nothing to do.
   } else if (lhs->IsDefault()) {
-    lhs->Set(default_ptr, rhs->Get(), lhs_arena);
+    lhs->Set(rhs->Get(), lhs_arena);
     // rhs needs to be destroyed before overwritten.
-    rhs->Destroy(default_ptr, rhs_arena);
-    rhs->InitDefault(default_ptr);
+    rhs->Destroy();
+    rhs->InitDefault();
   } else if (rhs->IsDefault()) {
-    rhs->Set(default_ptr, lhs->Get(), rhs_arena);
+    rhs->Set(lhs->Get(), rhs_arena);
     // lhs needs to be destroyed before overwritten.
-    lhs->Destroy(default_ptr, lhs_arena);
-    lhs->InitDefault(default_ptr);
+    lhs->Destroy();
+    lhs->InitDefault();
   } else {
     std::string temp = lhs->Get();
-    lhs->Set(default_ptr, rhs->Get(), lhs_arena);
-    rhs->Set(default_ptr, std::move(temp), rhs_arena);
+    lhs->Set(rhs->Get(), lhs_arena);
+    rhs->Set(std::move(temp), rhs_arena);
   }
 }
 
@@ -1266,20 +1256,17 @@ void Reflection::ClearField(Message* message,
         case FieldDescriptor::CPPTYPE_STRING: {
           switch (field->options().ctype()) {
             default:  // TODO(kenton):  Support other string reps.
-            case FieldOptions::STRING: {
+            case FieldOptions::STRING:
               if (IsInlined(field)) {
                 // Currently, string with default value can't be inlined. So we
                 // don't have to handle default value here.
                 MutableRaw<InlinedStringField>(message, field)->ClearToEmpty();
-                break;
+              } else {
+                auto* str = MutableRaw<ArenaStringPtr>(message, field);
+                str->Destroy();
+                str->InitDefault();
               }
-              const std::string* default_ptr =
-                  DefaultRaw<ArenaStringPtr>(field).GetPointer();
-              MutableRaw<ArenaStringPtr>(message, field)
-                  ->SetAllocated(default_ptr, nullptr,
-                                 message->GetArenaForAllocation());
               break;
-            }
           }
           break;
         }
@@ -1658,17 +1645,13 @@ std::string Reflection::GetString(const Message& message,
     }
     switch (field->options().ctype()) {
       default:  // TODO(kenton):  Support other string reps.
-      case FieldOptions::STRING: {
+      case FieldOptions::STRING:
         if (IsInlined(field)) {
           return GetField<InlinedStringField>(message, field).GetNoArena();
+        } else {
+          const auto& str = GetField<ArenaStringPtr>(message, field);
+          return str.IsDefault() ? field->default_value_string() : str.Get();
         }
-
-        if (auto* value =
-                GetField<ArenaStringPtr>(message, field).GetPointer()) {
-          return *value;
-        }
-        return field->default_value_string();
-      }
     }
   }
 }
@@ -1687,17 +1670,13 @@ const std::string& Reflection::GetStringReference(const Message& message,
     }
     switch (field->options().ctype()) {
       default:  // TODO(kenton):  Support other string reps.
-      case FieldOptions::STRING: {
+      case FieldOptions::STRING:
         if (IsInlined(field)) {
           return GetField<InlinedStringField>(message, field).GetNoArena();
+        } else {
+          const auto& str = GetField<ArenaStringPtr>(message, field);
+          return str.IsDefault() ? field->default_value_string() : str.Get();
         }
-
-        if (auto* value =
-                GetField<ArenaStringPtr>(message, field).GetPointer()) {
-          return *value;
-        }
-        return field->default_value_string();
-      }
     }
   }
 }
@@ -1720,7 +1699,7 @@ void Reflection::SetString(Message* message, const FieldDescriptor* field,
               &MutableInlinedStringDonatedArray(message)[index / 32];
           uint32_t mask = ~(static_cast<uint32_t>(1) << (index % 32));
           MutableField<InlinedStringField>(message, field)
-              ->Set(nullptr, value, message->GetArenaForAllocation(),
+              ->Set(value, message->GetArenaForAllocation(),
                     IsInlinedStringDonated(*message, field), states, mask,
                     message);
           break;
@@ -1730,18 +1709,12 @@ void Reflection::SetString(Message* message, const FieldDescriptor* field,
         // We just need to pass some arbitrary default string to make it work.
         // This allows us to not have the real default accessible from
         // reflection.
-        const std::string* default_ptr =
-            schema_.InRealOneof(field)
-                ? nullptr
-                : DefaultRaw<ArenaStringPtr>(field).GetPointer();
         if (schema_.InRealOneof(field) && !HasOneofField(*message, field)) {
           ClearOneof(message, field->containing_oneof());
-          MutableField<ArenaStringPtr>(message, field)
-              ->InitDefault(default_ptr);
+          MutableField<ArenaStringPtr>(message, field)->InitDefault();
         }
         MutableField<ArenaStringPtr>(message, field)
-            ->Set(default_ptr, std::move(value),
-                  message->GetArenaForAllocation());
+            ->Set(std::move(value), message->GetArenaForAllocation());
         break;
       }
     }
@@ -2721,8 +2694,7 @@ void Reflection::ClearOneof(Message* message,
               // We just need to pass some arbitrary default string to make it
               // work. This allows us to not have the real default accessible
               // from reflection.
-              MutableField<ArenaStringPtr>(message, field)
-                  ->Destroy(nullptr, message->GetArenaForAllocation());
+              MutableField<ArenaStringPtr>(message, field)->Destroy();
               break;
             }
           }

src/google/protobuf/generated_message_tctable_impl.h

@@ -265,45 +265,9 @@ class PROTOBUF_EXPORT TcParser final {
   static const char* GenericFallback(PROTOBUF_TC_PARAM_DECL);
   static const char* GenericFallbackLite(PROTOBUF_TC_PARAM_DECL);
 
-  // Dispatch to the designated parse function
-  inline PROTOBUF_ALWAYS_INLINE static const char* TagDispatch(
-      PROTOBUF_TC_PARAM_DECL) {
-    const auto coded_tag = UnalignedLoad<uint16_t>(ptr);
-    const size_t idx = coded_tag & table->fast_idx_mask;
-    PROTOBUF_ASSUME((idx & 7) == 0);
-    auto* fast_entry = table->fast_entry(idx >> 3);
-    data = fast_entry->bits;
-    data.data ^= coded_tag;
-    PROTOBUF_MUSTTAIL return fast_entry->target(PROTOBUF_TC_PARAM_PASS);
-  }
-
-  // We can only safely call from field to next field if the call is optimized
-  // to a proper tail call. Otherwise we blow through stack. Clang and gcc
-  // reliably do this optimization in opt mode, but do not perform this in debug
-  // mode. Luckily the structure of the algorithm is such that it's always
-  // possible to just return and use the enclosing parse loop as a trampoline.
-  static const char* ToTagDispatch(PROTOBUF_TC_PARAM_DECL) {
-    constexpr bool always_return = !PROTOBUF_TAILCALL;
-    if (always_return || !ctx->DataAvailable(ptr)) {
-      PROTOBUF_MUSTTAIL return ToParseLoop(PROTOBUF_TC_PARAM_PASS);
-    }
-    PROTOBUF_MUSTTAIL return TagDispatch(PROTOBUF_TC_PARAM_PASS);
-  }
-
-  PROTOBUF_NOINLINE static const char* ParseLoop(
-      MessageLite* msg, const char* ptr, ParseContext* ctx,
-      const TcParseTableBase* table) {
-    ScopedArenaSwap saved(msg, ctx);
-    const uint32_t has_bits_offset = table->has_bits_offset;
-    while (!ctx->Done(&ptr)) {
-      uint64_t hasbits = 0;
-      if (has_bits_offset) hasbits = RefAt<uint32_t>(msg, has_bits_offset);
-      ptr = TagDispatch(msg, ptr, ctx, table, hasbits, {});
-      if (ptr == nullptr) break;
-      if (ctx->LastTag() != 1) break;  // Ended on terminating tag
-    }
-    return ptr;
-  }
+  static const char* ParseLoop(MessageLite* msg, const char* ptr,
+                               ParseContext* ctx,
+                               const TcParseTableBase* table);
 
   // Functions referenced by generated fast tables (numeric types):
   //   F: fixed      V: varint     Z: zigzag
@@ -424,16 +388,6 @@ class PROTOBUF_EXPORT TcParser final {
     return *target;
   }
 
-  static inline PROTOBUF_ALWAYS_INLINE void SyncHasbits(
-      MessageLite* msg, uint64_t hasbits, const TcParseTableBase* table) {
-    const uint32_t has_bits_offset = table->has_bits_offset;
-    if (has_bits_offset) {
-      // Only the first 32 has-bits are updated. Nothing above those is stored,
-      // but e.g. messages without has-bits update the upper bits.
-      RefAt<uint32_t>(msg, has_bits_offset) = static_cast<uint32_t>(hasbits);
-    }
-  }
-
   // Mini parsing:
   //
   // This function parses a field from incoming data based on metadata stored in
@@ -453,38 +407,24 @@ class PROTOBUF_EXPORT TcParser final {
   template <typename TagType>
   static inline const char* RepeatedParseMessageAuxImpl(PROTOBUF_TC_PARAM_DECL);
 
-  static inline PROTOBUF_ALWAYS_INLINE const char* ToParseLoop(
-      PROTOBUF_TC_PARAM_DECL) {
-    (void)data;
-    (void)ctx;
-    SyncHasbits(msg, hasbits, table);
-    return ptr;
+  static inline PROTOBUF_ALWAYS_INLINE void SyncHasbits(
+      MessageLite* msg, uint64_t hasbits, const TcParseTableBase* table) {
+    const uint32_t has_bits_offset = table->has_bits_offset;
+    if (has_bits_offset) {
+      // Only the first 32 has-bits are updated. Nothing above those is stored,
+      // but e.g. messages without has-bits update the upper bits.
+      RefAt<uint32_t>(msg, has_bits_offset) = static_cast<uint32_t>(hasbits);
+    }
   }
 
-  static inline PROTOBUF_ALWAYS_INLINE const char* Error(
-      PROTOBUF_TC_PARAM_DECL) {
-    (void)data;
-    (void)ctx;
-    (void)ptr;
-    SyncHasbits(msg, hasbits, table);
-    return nullptr;
-  }
+  static const char* TagDispatch(PROTOBUF_TC_PARAM_DECL);
+  static const char* ToTagDispatch(PROTOBUF_TC_PARAM_DECL);
+  static const char* ToParseLoop(PROTOBUF_TC_PARAM_DECL);
+  static const char* Error(PROTOBUF_TC_PARAM_DECL);
 
   static const char* FastUnknownEnumFallback(PROTOBUF_TC_PARAM_DECL);
 
-  class ScopedArenaSwap final {
-   public:
-    ScopedArenaSwap(MessageLite* msg, ParseContext* ctx)
-        : ctx_(ctx), saved_(ctx->data().arena) {
-      ctx_->data().arena = msg->GetArenaForAllocation();
-    }
-    ScopedArenaSwap(const ScopedArenaSwap&) = delete;
-    ~ScopedArenaSwap() { ctx_->data().arena = saved_; }
-
-   private:
-    ParseContext* const ctx_;
-    Arena* const saved_;
-  };
+  class ScopedArenaSwap;
 
   template <class MessageBaseT, class UnknownFieldsT>
   static const char* GenericFallbackImpl(PROTOBUF_TC_PARAM_DECL) {
@@ -555,6 +495,14 @@ class PROTOBUF_EXPORT TcParser final {
                           uint32_t field_num, ParseContext* ctx,
                           MessageLite* msg);
 
+  // UTF-8 validation:
+  static void ReportFastUtf8Error(uint16_t coded_tag,
+                                  const TcParseTableBase* table);
+  static bool MpVerifyUtf8(StringPiece wire_bytes,
+                           const TcParseTableBase* table,
+                           const TcParseTableBase::FieldEntry& entry,
+                           uint16_t xform_val);
+
   // For FindFieldEntry tests:
   friend class FindFieldEntryTest;
   static constexpr const uint32_t kMtSmallScanSize = 4;

src/google/protobuf/generated_message_tctable_lite.cc

@@ -46,8 +46,14 @@ namespace google {
 namespace protobuf {
 namespace internal {
 
+const uint32_t TcParser::kMtSmallScanSize;
+
 using FieldEntry = TcParseTableBase::FieldEntry;
 
+//////////////////////////////////////////////////////////////////////////////
+// Template instantiations:
+//////////////////////////////////////////////////////////////////////////////
+
 #ifndef NDEBUG
 template void AlignFail<4>(uintptr_t);
 template void AlignFail<8>(uintptr_t);
@@ -57,6 +63,86 @@ const char* TcParser::GenericFallbackLite(PROTOBUF_TC_PARAM_DECL) {
   return GenericFallbackImpl<MessageLite, std::string>(PROTOBUF_TC_PARAM_PASS);
 }
 
+//////////////////////////////////////////////////////////////////////////////
+// Core fast parsing implementation:
+//////////////////////////////////////////////////////////////////////////////
+
+class TcParser::ScopedArenaSwap final {
+ public:
+  ScopedArenaSwap(MessageLite* msg, ParseContext* ctx)
+      : ctx_(ctx), saved_(ctx->data().arena) {
+    ctx_->data().arena = msg->GetArenaForAllocation();
+  }
+  ScopedArenaSwap(const ScopedArenaSwap&) = delete;
+  ~ScopedArenaSwap() { ctx_->data().arena = saved_; }
+
+ private:
+  ParseContext* const ctx_;
+  Arena* const saved_;
+};
+
+PROTOBUF_NOINLINE const char* TcParser::ParseLoop(
+    MessageLite* msg, const char* ptr, ParseContext* ctx,
+    const TcParseTableBase* table) {
+  ScopedArenaSwap saved(msg, ctx);
+  const uint32_t has_bits_offset = table->has_bits_offset;
+  while (!ctx->Done(&ptr)) {
+    uint64_t hasbits = 0;
+    if (has_bits_offset) hasbits = RefAt<uint32_t>(msg, has_bits_offset);
+    ptr = TagDispatch(msg, ptr, ctx, table, hasbits, {});
+    if (ptr == nullptr) break;
+    if (ctx->LastTag() != 1) break;  // Ended on terminating tag
+  }
+  return ptr;
+}
+
+  // Dispatch to the designated parse function
+inline PROTOBUF_ALWAYS_INLINE const char* TcParser::TagDispatch(
+    PROTOBUF_TC_PARAM_DECL) {
+  const auto coded_tag = UnalignedLoad<uint16_t>(ptr);
+  const size_t idx = coded_tag & table->fast_idx_mask;
+  PROTOBUF_ASSUME((idx & 7) == 0);
+  auto* fast_entry = table->fast_entry(idx >> 3);
+  data = fast_entry->bits;
+  data.data ^= coded_tag;
+  PROTOBUF_MUSTTAIL return fast_entry->target(PROTOBUF_TC_PARAM_PASS);
+}
+
+// We can only safely call from field to next field if the call is optimized
+// to a proper tail call. Otherwise we blow through stack. Clang and gcc
+// reliably do this optimization in opt mode, but do not perform this in debug
+// mode. Luckily the structure of the algorithm is such that it's always
+// possible to just return and use the enclosing parse loop as a trampoline.
+inline PROTOBUF_ALWAYS_INLINE const char* TcParser::ToTagDispatch(
+    PROTOBUF_TC_PARAM_DECL) {
+  constexpr bool always_return = !PROTOBUF_TAILCALL;
+  if (always_return || !ctx->DataAvailable(ptr)) {
+    PROTOBUF_MUSTTAIL return ToParseLoop(PROTOBUF_TC_PARAM_PASS);
+  }
+  PROTOBUF_MUSTTAIL return TagDispatch(PROTOBUF_TC_PARAM_PASS);
+}
+
+inline PROTOBUF_ALWAYS_INLINE const char* TcParser::ToParseLoop(
+    PROTOBUF_TC_PARAM_DECL) {
+  (void)data;
+  (void)ctx;
+  SyncHasbits(msg, hasbits, table);
+  return ptr;
+}
+
+inline PROTOBUF_ALWAYS_INLINE const char* TcParser::Error(
+    PROTOBUF_TC_PARAM_DECL) {
+  (void)data;
+  (void)ctx;
+  (void)ptr;
+  SyncHasbits(msg, hasbits, table);
+  return nullptr;
+}
+
+//////////////////////////////////////////////////////////////////////////////
+// Core mini parsing implementation:
+//////////////////////////////////////////////////////////////////////////////
+
 // Returns the address of the field for `tag` in the table's field entries.
 // Returns nullptr if the field was not found.
 const TcParseTableBase::FieldEntry* TcParser::FindFieldEntry(
@@ -886,6 +972,17 @@ void PrintUTF8ErrorLog(StringPiece message_name,
                        StringPiece field_name, const char* operation_str,
                        bool emit_stacktrace);
 
+void TcParser::ReportFastUtf8Error(uint16_t coded_tag,
+                                   const TcParseTableBase* table) {
+  if (coded_tag > 127) {
+    coded_tag = (coded_tag & 0x7f) + ((coded_tag & 0xff00) >> 1);
+  }
+  uint32_t field_num = coded_tag >> 3;
+  const auto* entry = FindFieldEntry(table, field_num);
+  PrintUTF8ErrorLog(MessageName(table), FieldName(table, entry), "parsing",
+                    false);
+}
+
 namespace {
 
 PROTOBUF_NOINLINE
@@ -893,8 +990,7 @@ const char* SingularStringParserFallback(ArenaStringPtr* s, const char* ptr,
                                          EpsCopyInputStream* stream) {
   int size = ReadSize(&ptr);
   if (!ptr) return nullptr;
-  return stream->ReadString(
-      ptr, size, s->MutableNoArenaNoDefault(&GetEmptyStringAlreadyInited()));
+  return stream->ReadString(ptr, size, s->MutableNoCopy(nullptr));
 }
 
 }  // namespace
@@ -905,6 +1001,7 @@ PROTOBUF_ALWAYS_INLINE const char* TcParser::SingularString(
   if (PROTOBUF_PREDICT_FALSE(data.coded_tag<TagType>() != 0)) {
     PROTOBUF_MUSTTAIL return MiniParse(PROTOBUF_TC_PARAM_PASS);
   }
+  auto saved_tag = UnalignedLoad<TagType>(ptr);
   ptr += sizeof(TagType);
   hasbits |= (uint64_t{1} << data.hasbit_idx());
   auto& field = RefAt<ArenaStringPtr>(msg, data.offset());
@@ -925,7 +1022,7 @@ PROTOBUF_ALWAYS_INLINE const char* TcParser::SingularString(
       if (PROTOBUF_PREDICT_TRUE(IsStructurallyValidUTF8(field.Get()))) {
         return ToParseLoop(PROTOBUF_TC_PARAM_PASS);
       }
-      PrintUTF8ErrorLog("", "unknown", "parsing", false);
+      ReportFastUtf8Error(saved_tag, table);
       return utf8 == kUtf8 ? Error(PROTOBUF_TC_PARAM_PASS)
                            : ToParseLoop(PROTOBUF_TC_PARAM_PASS);
   }
@@ -971,11 +1068,19 @@ PROTOBUF_ALWAYS_INLINE const char* TcParser::RepeatedString(
     if (ptr == nullptr) {
       return Error(PROTOBUF_TC_PARAM_PASS);
     }
-    if (utf8 != kNoUtf8) {
-      if (PROTOBUF_PREDICT_FALSE(!IsStructurallyValidUTF8(*str))) {
-        PrintUTF8ErrorLog("", "unknown", "parsing", false);
+    switch (utf8) {
+      case kNoUtf8:
+#ifdef NDEBUG
+      case kUtf8ValidateOnly:
+#endif
+        break;
+      default:
+        if (PROTOBUF_PREDICT_TRUE(IsStructurallyValidUTF8(*str))) {
+          break;
+        }
+        ReportFastUtf8Error(expected_tag, table);
         if (utf8 == kUtf8) return Error(PROTOBUF_TC_PARAM_PASS);
-      }
+        break;
     }
     if (!ctx->DataAvailable(ptr)) break;
   } while (UnalignedLoad<TagType>(ptr) == expected_tag);
@@ -1058,11 +1163,10 @@ bool TcParser::ChangeOneof(const TcParseTableBase* table,
   uint16_t current_kind = current_entry->type_card & field_layout::kFkMask;
   uint16_t current_rep = current_entry->type_card & field_layout::kRepMask;
   if (current_kind == field_layout::kFkString) {
-    Arena* arena = ctx->data().arena;
     switch (current_rep) {
       case field_layout::kRepAString: {
         auto& field = RefAt<ArenaStringPtr>(msg, current_entry->offset);
-        field.Destroy(ArenaStringPtr::EmptyDefault{}, arena);
+        field.Destroy();
         break;
       }
       case field_layout::kRepSString:
@@ -1383,23 +1487,28 @@ const char* TcParser::MpPackedVarint(PROTOBUF_TC_PARAM_DECL) {
   return Error(PROTOBUF_TC_PARAM_PASS);
 }
 
-namespace {
-
-inline bool MpVerifyUtf8(StringPiece wire_bytes, const FieldEntry& entry,
-                         uint16_t xform_val) {
+bool TcParser::MpVerifyUtf8(StringPiece wire_bytes,
+                            const TcParseTableBase* table,
+                            const FieldEntry& entry, uint16_t xform_val) {
   if (xform_val == field_layout::kTvUtf8) {
-    return VerifyUTF8(wire_bytes, "unknown");
+    if (!IsStructurallyValidUTF8(wire_bytes)) {
+      PrintUTF8ErrorLog(MessageName(table), FieldName(table, &entry), "parsing",
+                        false);
+      return false;
+    }
+    return true;
   }
 #ifndef NDEBUG
   if (xform_val == field_layout::kTvUtf8Debug) {
-    VerifyUTF8(wire_bytes, "unknown");
+    if (!IsStructurallyValidUTF8(wire_bytes)) {
+      PrintUTF8ErrorLog(MessageName(table), FieldName(table, &entry), "parsing",
+                        false);
+    }
   }
 #endif  // NDEBUG
   return true;
 }
 
-}  // namespace
-
 const char* TcParser::MpString(PROTOBUF_TC_PARAM_DECL) {
   const auto& entry = RefAt<FieldEntry>(table, data.entry_offset());
   const uint16_t type_card = entry.type_card;
@@ -1413,18 +1522,6 @@ const char* TcParser::MpString(PROTOBUF_TC_PARAM_DECL) {
     PROTOBUF_MUSTTAIL return MpRepeatedString(PROTOBUF_TC_PARAM_PASS);
   }
   const uint16_t xform_val = type_card & field_layout::kTvMask;
-
-  // TODO(b/209516305): handle UTF-8 fields once field names are available.
-  if (
-#ifdef NDEBUG
-      xform_val == field_layout::kTvUtf8
-#else
-      xform_val != 0
-#endif
-  ) {
-    PROTOBUF_MUSTTAIL return table->fallback(PROTOBUF_TC_PARAM_PASS);
-  }
-
   const uint16_t rep = type_card & field_layout::kRepMask;
   if (rep == field_layout::kRepIString) {
     // TODO(b/198211897): support InilnedStringField.
@@ -1444,19 +1541,16 @@ const char* TcParser::MpString(PROTOBUF_TC_PARAM_DECL) {
   Arena* arena = ctx->data().arena;
   switch (rep) {
     case field_layout::kRepAString: {
-      const std::string* default_value =
-          RefAt<ArenaStringPtr>(table->default_instance, entry.offset)
-              .tagged_ptr_.Get();
       auto& field = RefAt<ArenaStringPtr>(msg, entry.offset);
       if (need_init) field.InitDefault();
       if (arena) {
         ptr = ctx->ReadArenaString(ptr, &field, arena);
       } else {
-        std::string* str = field.MutableNoCopy(default_value, nullptr);
+        std::string* str = field.MutableNoCopy(nullptr);
         ptr = InlineGreedyStringParser(str, ptr, ctx);
       }
       if (!ptr) break;
-      is_valid = MpVerifyUtf8(field.Get(), entry, xform_val);
+      is_valid = MpVerifyUtf8(field.Get(), table, entry, xform_val);
       break;
     }
 
@@ -1482,18 +1576,6 @@ const char* TcParser::MpRepeatedString(PROTOBUF_TC_PARAM_DECL) {
 
   const uint16_t rep = type_card & field_layout::kRepMask;
   const uint16_t xform_val = type_card & field_layout::kTvMask;
-
-  // TODO(b/209516305): handle UTF-8 fields once field names are available.
-  if (
-#ifdef NDEBUG
-      xform_val == field_layout::kTvUtf8
-#else
-      xform_val != 0
-#endif
-  ) {
-    PROTOBUF_MUSTTAIL return table->fallback(PROTOBUF_TC_PARAM_PASS);
-  }
-
   switch (rep) {
     case field_layout::kRepSString: {
       auto& field = RefAt<RepeatedPtrField<std::string>>(msg, entry.offset);
@@ -1503,8 +1585,9 @@ const char* TcParser::MpRepeatedString(PROTOBUF_TC_PARAM_DECL) {
         ptr = ptr2;
         std::string* str = field.Add();
         ptr = InlineGreedyStringParser(str, ptr, ctx);
-        if (PROTOBUF_PREDICT_FALSE(ptr == nullptr ||
-                                   !MpVerifyUtf8(*str, entry, xform_val))) {
+        if (PROTOBUF_PREDICT_FALSE(
+                ptr == nullptr ||
+                !MpVerifyUtf8(*str, table, entry, xform_val))) {
           return Error(PROTOBUF_TC_PARAM_PASS);
         }
         if (!ctx->DataAvailable(ptr)) break;

src/google/protobuf/generated_message_tctable_lite_test.cc

@@ -88,11 +88,11 @@ TEST(IsEntryForFieldNumTest, Matcher) {
 }  // namespace
 
 class FindFieldEntryTest : public ::testing::Test {
- protected:
+ public:
   // Calls the private `FindFieldEntry` function.
   template <size_t kFastTableSizeLog2, size_t kNumEntries, size_t kNumFieldAux,
             size_t kNameTableSize>
-  const TcParseTableBase::FieldEntry* FindFieldEntry(
+  static const TcParseTableBase::FieldEntry* FindFieldEntry(
       const TcParseTable<kFastTableSizeLog2, kNumEntries, kNumFieldAux,
                          kNameTableSize>& table,
       uint32_t tag) {
@@ -102,7 +102,7 @@ class FindFieldEntryTest : public ::testing::Test {
   // Calls the private `FieldName` function.
   template <size_t kFastTableSizeLog2, size_t kNumEntries, size_t kNumFieldAux,
             size_t kNameTableSize>
-  StringPiece FieldName(
+  static StringPiece FieldName(
       const TcParseTable<kFastTableSizeLog2, kNumEntries, kNumFieldAux,
                          kNameTableSize>& table,
       const TcParseTableBase::FieldEntry* entry) {
@@ -112,7 +112,7 @@ class FindFieldEntryTest : public ::testing::Test {
   // Calls the private `MessageName` function.
   template <size_t kFastTableSizeLog2, size_t kNumEntries, size_t kNumFieldAux,
             size_t kNameTableSize>
-  StringPiece MessageName(
+  static StringPiece MessageName(
       const TcParseTable<kFastTableSizeLog2, kNumEntries, kNumFieldAux,
                          kNameTableSize>& table) {
     return TcParser::MessageName(&table.header);
@@ -293,196 +293,197 @@ TEST_F(FindFieldEntryTest, EmptyMessage) {
   EXPECT_THAT(MessageName(table), Eq("MessageName"));
 }
 
-TEST_F(FindFieldEntryTest, BigMessage) {
-  // Make a monster with lots of field numbers
-  // clang-format off
-  const TcParseTable<5, 134, 5, 2176> test_all_types_table = {
-      // header:
-      {
-          0, 0, 0, 0,  // has_bits_offset, extensions
-          418, 248,    // max_field_number, fast_idx_mask
-          14, 1,       // num_sequential_fields, sequential_fields_start
-          135,         // num_field_entries
-          5,           // num_aux_entries
-          offsetof(decltype(test_all_types_table), aux_entries),
-          nullptr,     // default instance
-          nullptr,     // fallback function
-      },
-      {{
-          // tail-call table
-      }},
-      {{// field numbers
-        1,   2,   3,   4,   5,   6,   7,   8,   9,  10,
-       11,  12,  13,  14,  15,  18,  19,  21,  22,  24,
-       25,  27,  31,  32,  33,  34,  35,  36,  37,  38,
-       39,  40,  41,  42,  43,  44,  45,  48,  49,  51,
-       52,  54,  55,  56,  57,  58,  59,  60,  61,  62,
-       63,  64,  65,  66,  67,  68,  69,  70,  71,  72,
-       73,  74,  75,  76,  77,  78,  79,  80,  81,  82,
-       83,  84,  85,  86,  87,  88,  89,  90,  91,  92,
-       93,  94,  95,  96,  97,  98,  99, 100, 101, 102,
-      111, 112, 113, 114, 115, 116, 117, 118, 119, 201,
-      241, 242, 243, 244, 245, 246, 247, 248, 249, 250,
-      251, 252, 253, 254, 255, 321, 322, 401, 402, 403,
-      404, 405, 406, 407, 408, 409, 410, 411, 412, 413,
-      414, 415, 416, 417}},
+// Make a monster with lots of field numbers
+// clang-format off
+const TcParseTable<5, 134, 5, 2176> test_all_types_table = {
+    // header:
+    {
+        0, 0, 0, 0,  // has_bits_offset, extensions
+        418, 248,    // max_field_number, fast_idx_mask
+        14, 1,       // num_sequential_fields, sequential_fields_start
+        135,         // num_field_entries
+        5,           // num_aux_entries
+        offsetof(decltype(test_all_types_table), aux_entries),
+        nullptr,     // default instance
+        nullptr,     // fallback function
+    },
     {{
-        // "mini" table
-    }},
-    {{  // auxiliary entries (not used in this test)
-        {-1, 4},
-        {-1, 4},
-        {-1, 4},
-        {-1, 4},
-        {-1, 4},
-      }}, {{  // name lengths
-        "\1"  // message name
-        "\16\16\17\17\17\17\20\20\21\21\16\17\15\17\16\27\30\24\25\25"
-        "\15\21\16\16\17\17\17\17\20\20\21\21\16\17\15\17\16\27\30\24"
-        "\25\25\15\17\17\21\21\21\21\23\23\25\25\17\20\15\21\20\31\32"
-        "\26\27\14\14\15\15\15\15\16\16\17\17\14\15\13\22\16\16\17\17"
-        "\17\17\20\20\21\21\16\17\15\24\14\24\14\13\12\14\13\14\12\4"
-        "\15\15\16\16\16\16\17\17\20\20\15\16\14\16\15\25\25\12\13\14"
-        "\15\13\15\12\12\13\14\14\14\16\16\15\15\16\0"
-          // names
-        "M"
-        "optional_int32"
-        "optional_int64"
-        "optional_uint32"
-        "optional_uint64"
-        "optional_sint32"
-        "optional_sint64"
-        "optional_fixed32"
-        "optional_fixed64"
-        "optional_sfixed32"
-        "optional_sfixed64"
-        "optional_float"
-        "optional_double"
-        "optional_bool"
-        "optional_string"
-        "optional_bytes"
-        "optional_nested_message"
-        "optional_foreign_message"
-        "optional_nested_enum"
-        "optional_foreign_enum"
-        "optional_string_piece"
-        "optional_cord"
-        "recursive_message"
-        "repeated_int32"
-        "repeated_int64"
-        "repeated_uint32"
-        "repeated_uint64"
-        "repeated_sint32"
-        "repeated_sint64"
-        "repeated_fixed32"
-        "repeated_fixed64"
-        "repeated_sfixed32"
-        "repeated_sfixed64"
-        "repeated_float"
-        "repeated_double"
-        "repeated_bool"
-        "repeated_string"
-        "repeated_bytes"
-        "repeated_nested_message"
-        "repeated_foreign_message"
-        "repeated_nested_enum"
-        "repeated_foreign_enum"
-        "repeated_string_piece"
-        "repeated_cord"
-        "map_int32_int32"
-        "map_int64_int64"
-        "map_uint32_uint32"
-        "map_uint64_uint64"
-        "map_sint32_sint32"
-        "map_sint64_sint64"
-        "map_fixed32_fixed32"
-        "map_fixed64_fixed64"
-        "map_sfixed32_sfixed32"
-        "map_sfixed64_sfixed64"
-        "map_int32_float"
-        "map_int32_double"
-        "map_bool_bool"
-        "map_string_string"
-        "map_string_bytes"
-        "map_string_nested_message"
-        "map_string_foreign_message"
-        "map_string_nested_enum"
-        "map_string_foreign_enum"
-        "packed_int32"
-        "packed_int64"
-        "packed_uint32"
-        "packed_uint64"
-        "packed_sint32"
-        "packed_sint64"
-        "packed_fixed32"
-        "packed_fixed64"
-        "packed_sfixed32"
-        "packed_sfixed64"
-        "packed_float"
-        "packed_double"
-        "packed_bool"
-        "packed_nested_enum"
-        "unpacked_int32"
-        "unpacked_int64"
-        "unpacked_uint32"
-        "unpacked_uint64"
-        "unpacked_sint32"
-        "unpacked_sint64"
-        "unpacked_fixed32"
-        "unpacked_fixed64"
-        "unpacked_sfixed32"
-        "unpacked_sfixed64"
-        "unpacked_float"
-        "unpacked_double"
-        "unpacked_bool"
-        "unpacked_nested_enum"
-        "oneof_uint32"
-        "oneof_nested_message"
-        "oneof_string"
-        "oneof_bytes"
-        "oneof_bool"
-        "oneof_uint64"
-        "oneof_float"
-        "oneof_double"
-        "oneof_enum"
-        "data"
-        "default_int32"
-        "default_int64"
-        "default_uint32"
-        "default_uint64"
-        "default_sint32"
-        "default_sint64"
-        "default_fixed32"
-        "default_fixed64"
-        "default_sfixed32"
-        "default_sfixed64"
-        "default_float"
-        "default_double"
-        "default_bool"
-        "default_string"
-        "default_bytes"
-        "optional_lazy_message"
-        "repeated_lazy_message"
-        "fieldname1"
-        "field_name2"
-        "_field_name3"
-        "field__name4_"
-        "field0name5"
-        "field_0_name6"
-        "fieldName7"
-        "FieldName8"
-        "field_Name9"
-        "Field_Name10"
-        "FIELD_NAME11"
-        "FIELD_name12"
-        "__field_name13"
-        "__Field_name14"
-        "field__name15"
-        "field__Name16"
-        "field_name17__"
+        // tail-call table
     }},
-  };
-  // clang-format on
+    {{// field numbers
+      1,   2,   3,   4,   5,   6,   7,   8,   9,  10,
+     11,  12,  13,  14,  15,  18,  19,  21,  22,  24,
+     25,  27,  31,  32,  33,  34,  35,  36,  37,  38,
+     39,  40,  41,  42,  43,  44,  45,  48,  49,  51,
+     52,  54,  55,  56,  57,  58,  59,  60,  61,  62,
+     63,  64,  65,  66,  67,  68,  69,  70,  71,  72,
+     73,  74,  75,  76,  77,  78,  79,  80,  81,  82,
+     83,  84,  85,  86,  87,  88,  89,  90,  91,  92,
+     93,  94,  95,  96,  97,  98,  99, 100, 101, 102,
+    111, 112, 113, 114, 115, 116, 117, 118, 119, 201,
+    241, 242, 243, 244, 245, 246, 247, 248, 249, 250,
+    251, 252, 253, 254, 255, 321, 322, 401, 402, 403,
+    404, 405, 406, 407, 408, 409, 410, 411, 412, 413,
+    414, 415, 416, 417}},
+  {{
+      // "mini" table
+  }},
+  {{  // auxiliary entries (not used in this test)
+      {-1, 4},
+      {-1, 4},
+      {-1, 4},
+      {-1, 4},
+      {-1, 4},
+    }}, {{  // name lengths
+      "\1"  // message name
+      "\16\16\17\17\17\17\20\20\21\21\16\17\15\17\16\27\30\24\25\25"
+      "\15\21\16\16\17\17\17\17\20\20\21\21\16\17\15\17\16\27\30\24"
+      "\25\25\15\17\17\21\21\21\21\23\23\25\25\17\20\15\21\20\31\32"
+      "\26\27\14\14\15\15\15\15\16\16\17\17\14\15\13\22\16\16\17\17"
+      "\17\17\20\20\21\21\16\17\15\24\14\24\14\13\12\14\13\14\12\4"
+      "\15\15\16\16\16\16\17\17\20\20\15\16\14\16\15\25\25\12\13\14"
+      "\15\13\15\12\12\13\14\14\14\16\16\15\15\16\0"
+        // names
+      "M"
+      "optional_int32"
+      "optional_int64"
+      "optional_uint32"
+      "optional_uint64"
+      "optional_sint32"
+      "optional_sint64"
+      "optional_fixed32"
+      "optional_fixed64"
+      "optional_sfixed32"
+      "optional_sfixed64"
+      "optional_float"
+      "optional_double"
+      "optional_bool"
+      "optional_string"
+      "optional_bytes"
+      "optional_nested_message"
+      "optional_foreign_message"
+      "optional_nested_enum"
+      "optional_foreign_enum"
+      "optional_string_piece"
+      "optional_cord"
+      "recursive_message"
+      "repeated_int32"
+      "repeated_int64"
+      "repeated_uint32"
+      "repeated_uint64"
+      "repeated_sint32"
+      "repeated_sint64"
+      "repeated_fixed32"
+      "repeated_fixed64"
+      "repeated_sfixed32"
+      "repeated_sfixed64"
+      "repeated_float"
+      "repeated_double"
+      "repeated_bool"
+      "repeated_string"
+      "repeated_bytes"
+      "repeated_nested_message"
+      "repeated_foreign_message"
+      "repeated_nested_enum"
+      "repeated_foreign_enum"
+      "repeated_string_piece"
+      "repeated_cord"
+      "map_int32_int32"
+      "map_int64_int64"
+      "map_uint32_uint32"
+      "map_uint64_uint64"
+      "map_sint32_sint32"
+      "map_sint64_sint64"
+      "map_fixed32_fixed32"
+      "map_fixed64_fixed64"
+      "map_sfixed32_sfixed32"
+      "map_sfixed64_sfixed64"
+      "map_int32_float"
+      "map_int32_double"
+      "map_bool_bool"
+      "map_string_string"
+      "map_string_bytes"
+      "map_string_nested_message"
+      "map_string_foreign_message"
+      "map_string_nested_enum"
+      "map_string_foreign_enum"
+      "packed_int32"
+      "packed_int64"
+      "packed_uint32"
+      "packed_uint64"
+      "packed_sint32"
+      "packed_sint64"
+      "packed_fixed32"
+      "packed_fixed64"
+      "packed_sfixed32"
+      "packed_sfixed64"
+      "packed_float"
+      "packed_double"
+      "packed_bool"
+      "packed_nested_enum"
+      "unpacked_int32"
+      "unpacked_int64"
+      "unpacked_uint32"
+      "unpacked_uint64"
+      "unpacked_sint32"
+      "unpacked_sint64"
+      "unpacked_fixed32"
+      "unpacked_fixed64"
+      "unpacked_sfixed32"
+      "unpacked_sfixed64"
+      "unpacked_float"
+      "unpacked_double"
+      "unpacked_bool"
+      "unpacked_nested_enum"
+      "oneof_uint32"
+      "oneof_nested_message"
+      "oneof_string"
+      "oneof_bytes"
+      "oneof_bool"
+      "oneof_uint64"
+      "oneof_float"
+      "oneof_double"
+      "oneof_enum"
+      "data"
+      "default_int32"
+      "default_int64"
+      "default_uint32"
+      "default_uint64"
+      "default_sint32"
+      "default_sint64"
+      "default_fixed32"
+      "default_fixed64"
+      "default_sfixed32"
+      "default_sfixed64"
+      "default_float"
+      "default_double"
+      "default_bool"
+      "default_string"
+      "default_bytes"
+      "optional_lazy_message"
+      "repeated_lazy_message"
+      "fieldname1"
+      "field_name2"
+      "_field_name3"
+      "field__name4_"
+      "field0name5"
+      "field_0_name6"
+      "fieldName7"
+      "FieldName8"
+      "field_Name9"
+      "Field_Name10"
+      "FIELD_NAME11"
+      "FIELD_name12"
+      "__field_name13"
+      "__Field_name14"
+      "field__name15"
+      "field__Name16"
+      "field_name17__"
+  }},
+};
+// clang-format on
+
+TEST_F(FindFieldEntryTest, BigMessage) {
   EXPECT_THAT(MessageName(test_all_types_table), Eq("M"));
   for (int field_num :
        {1, 12, 31, 42, 57, 68, 79, 90, 101, 119, 249, 402, 412}) {

src/google/protobuf/generated_message_util.cc

@@ -389,8 +389,7 @@ void GenericSwap(MessageLite* m1, MessageLite* m2) {
 MessageLite* GetOwnedMessageInternal(Arena* message_arena,
                                      MessageLite* submessage,
                                      Arena* submessage_arena) {
-  GOOGLE_DCHECK(Arena::InternalHelper<MessageLite>::GetOwningArena(submessage) ==
-         submessage_arena);
+  GOOGLE_DCHECK(Arena::InternalGetOwningArena(submessage) == submessage_arena);
   GOOGLE_DCHECK(message_arena != submessage_arena);
   GOOGLE_DCHECK_EQ(submessage_arena, nullptr);
   if (message_arena != nullptr && submessage_arena == nullptr) {

src/google/protobuf/inlined_string_field.cc

@@ -55,8 +55,7 @@ std::string* InlinedStringField::Mutable(const LazyString& /*default_value*/,
   return MutableSlow(arena, donated, donating_states, mask, msg);
 }
 
-std::string* InlinedStringField::Mutable(ArenaStringPtr::EmptyDefault,
-                                         Arena* arena, bool donated,
+std::string* InlinedStringField::Mutable(Arena* arena, bool donated,
                                          uint32_t* donating_states,
                                          uint32_t mask, MessageLite* msg) {
   if (arena == nullptr || !donated) {
@@ -83,27 +82,28 @@ void InlinedStringField::SetAllocated(const std::string* default_value,
   SetAllocatedNoArena(default_value, value);
 }
 
-void InlinedStringField::Set(const std::string* default_value,
-                             std::string&& value, Arena* arena, bool donated,
+void InlinedStringField::Set(std::string&& value, Arena* arena, bool donated,
                              uint32_t* donating_states, uint32_t mask,
                              MessageLite* msg) {
   (void)donating_states;
   (void)mask;
   (void)msg;
-  SetNoArena(default_value, std::move(value));
+  SetNoArena(std::move(value));
 }
 
-std::string* InlinedStringField::Release(const std::string* default_value,
-                                         Arena* arena, bool donated) {
-  if (arena == nullptr && !donated) {
-    return ReleaseNonDefaultNoArena(default_value);
-  }
-  return ReleaseNonDefault(default_value, arena);
+std::string* InlinedStringField::Release() {
+  auto* released = new std::string(std::move(*get_mutable()));
+  get_mutable()->clear();
+  return released;
 }
 
-std::string* InlinedStringField::ReleaseNonDefault(
-    const std::string* default_value, Arena* arena) {
-  return ReleaseNonDefaultNoArena(default_value);
+std::string* InlinedStringField::Release(Arena* arena, bool donated) {
+  // We can not steal donated arena strings.
+  std::string* released = (arena != nullptr && donated)
+                              ? new std::string(*get_mutable())
+                              : new std::string(std::move(*get_mutable()));
+  get_mutable()->clear();
+  return released;
 }
 
 void InlinedStringField::ClearToDefault(const LazyString& default_value,

src/google/protobuf/inlined_string_field.h

@@ -130,63 +130,45 @@ class PROTOBUF_EXPORT InlinedStringField {
   //   `donated == ((donating_states & ~mask) != 0)`
   //
   // This method never changes the `donating_states`.
-  void Set(const std::string* default_value, ConstStringParam value,
-           Arena* arena, bool donated, uint32_t* /*donating_states*/,
-           uint32_t /*mask*/, MessageLite* /*msg*/) {
-    (void)arena;
-    (void)donated;
-    SetNoArena(default_value, value);
-  }
+  void Set(ConstStringParam value, Arena* arena, bool donated,
+           uint32_t* donating_states, uint32_t mask, MessageLite* msg);
 
   // Rvalue Set. If this field is donated, this method will undonate this field
   // by mutating the `donating_states` according to `mask`.
-  void Set(const std::string* default_value, std::string&& value, Arena* arena,
-           bool donated, uint32_t* donating_states, uint32_t mask,
-           MessageLite* msg);
+  void Set(std::string&& value, Arena* arena, bool donated,
+           uint32_t* donating_states, uint32_t mask, MessageLite* msg);
 
-  template <typename FirstParam>
-  void Set(FirstParam p1, const char* str, ::google::protobuf::Arena* arena, bool donated,
-           uint32_t* donating_states, uint32_t mask, MessageLite* msg) {
-    Set(p1, ConstStringParam(str), arena, donated, donating_states, mask, msg);
-  }
+  void Set(const char* str, ::google::protobuf::Arena* arena, bool donated,
+           uint32_t* donating_states, uint32_t mask, MessageLite* msg);
 
-  template <typename FirstParam>
-  void Set(FirstParam p1, const char* str, size_t size, ::google::protobuf::Arena* arena,
-           bool donated, uint32_t* donating_states, uint32_t mask,
-           MessageLite* msg) {
-    ConstStringParam sp{str, size};  // for string_view and `const string &`
-    Set(p1, sp, arena, donated, donating_states, mask, msg);
-  }
+  void Set(const char* str, size_t size, ::google::protobuf::Arena* arena, bool donated,
+           uint32_t* donating_states, uint32_t mask, MessageLite* msg);
 
-  template <typename FirstParam, typename RefWrappedType>
-  void Set(FirstParam p1,
-           std::reference_wrapper<RefWrappedType> const_string_ref,
+  template <typename RefWrappedType>
+  void Set(std::reference_wrapper<RefWrappedType> const_string_ref,
            ::google::protobuf::Arena* arena, bool donated, uint32_t* donating_states,
-           uint32_t mask, MessageLite* msg) {
-    Set(p1, const_string_ref.get(), arena, donated, donating_states, mask, msg);
-  }
+           uint32_t mask, MessageLite* msg);
+
+  void SetBytes(ConstStringParam value, Arena* arena, bool donated,
+                uint32_t* donating_states, uint32_t mask, MessageLite* msg);
 
-  template <typename FirstParam, typename SecondParam>
-  void SetBytes(FirstParam p1, SecondParam&& p2, ::google::protobuf::Arena* arena,
+  void SetBytes(std::string&& value, Arena* arena, bool donated,
+                uint32_t* donating_states, uint32_t mask, MessageLite* msg);
+
+  void SetBytes(const char* str, ::google::protobuf::Arena* arena, bool donated,
+                uint32_t* donating_states, uint32_t mask, MessageLite* msg);
+
+  void SetBytes(const void* p, size_t size, ::google::protobuf::Arena* arena,
                 bool donated, uint32_t* donating_states, uint32_t mask,
-                MessageLite* msg) {
-    Set(p1, static_cast<SecondParam&&>(p2), arena, donated, donating_states,
-        mask, msg);
-  }
+                MessageLite* msg);
 
-  template <typename FirstParam>
-  void SetBytes(FirstParam p1, const void* str, size_t size,
+  template <typename RefWrappedType>
+  void SetBytes(std::reference_wrapper<RefWrappedType> const_string_ref,
                 ::google::protobuf::Arena* arena, bool donated, uint32_t* donating_states,
-                uint32_t mask, MessageLite* msg) {
-    // Must work whether ConstStringParam is string_view or `const string &`
-    ConstStringParam sp{static_cast<const char*>(str), size};
-    Set(p1, sp, arena, donated, donating_states, mask, msg);
-  }
+                uint32_t mask, MessageLite* msg);
 
-  PROTOBUF_NDEBUG_INLINE void SetNoArena(const std::string* default_value,
-                                         StringPiece value);
-  PROTOBUF_NDEBUG_INLINE void SetNoArena(const std::string* default_value,
-                                         std::string&& value);
+  PROTOBUF_NDEBUG_INLINE void SetNoArena(StringPiece value);
+  PROTOBUF_NDEBUG_INLINE void SetNoArena(std::string&& value);
 
   // Basic accessors.
   PROTOBUF_NDEBUG_INLINE const std::string& Get() const { return GetNoArena(); }
@@ -196,22 +178,17 @@ class PROTOBUF_EXPORT InlinedStringField {
   // field is donated, this method undonates this field by mutating the
   // `donating_states` according to `mask`, and copies the content of the
   // original string to the returning string.
+  std::string* Mutable(Arena* arena, bool donated, uint32_t* donating_states,
+                       uint32_t mask, MessageLite* msg);
   std::string* Mutable(const LazyString& default_value, Arena* arena,
                        bool donated, uint32_t* donating_states, uint32_t mask,
                        MessageLite* msg);
-  std::string* Mutable(ArenaStringPtr::EmptyDefault, Arena* arena, bool donated,
-                       uint32_t* donating_states, uint32_t mask,
-                       MessageLite* msg);
 
-  // Release returns a std::string* instance that is heap-allocated and is not
-  // Own()'d by any arena. If the field is not set, this returns nullptr. The
-  // caller retains ownership. Clears this field back to nullptr state. Used to
-  // implement release_<field>() methods on generated classes.
-  PROTOBUF_NODISCARD std::string* Release(const std::string* default_value,
-                                          Arena* arena, bool donated);
-  PROTOBUF_NODISCARD std::string* ReleaseNonDefault(
-      const std::string* default_value, Arena* arena);
-  std::string* ReleaseNonDefaultNoArena(const std::string* default_value);
+  // Mutable(nullptr_t) is an overload to explicitly support Mutable(nullptr)
+  // calls used by the internal parser logic. This provides API equivalence with
+  // ArenaStringPtr, while still protecting against calls with arena pointers.
+  std::string* Mutable(std::nullptr_t);
+  std::string* MutableNoCopy(std::nullptr_t);
 
   // Takes a std::string that is heap-allocated, and takes ownership. The
   // std::string's destructor is registered with the arena. Used to implement
@@ -226,6 +203,120 @@ class PROTOBUF_EXPORT InlinedStringField {
   void SetAllocatedNoArena(const std::string* default_value,
                            std::string* value);
 
+  // Release returns a std::string* instance that is heap-allocated and is not
+  // Own()'d by any arena. If the field is not set, this returns nullptr. The
+  // caller retains ownership. Clears this field back to nullptr state. Used to
+  // implement release_<field>() methods on generated classes.
+  PROTOBUF_NODISCARD std::string* Release(Arena* arena, bool donated);
+  PROTOBUF_NODISCARD std::string* Release();
+
+  // --------------------------------------------------------
+  // Below functions will be removed in subsequent code change
+  // --------------------------------------------------------
+#ifdef DEPRECATED_METHODS_TO_BE_DELETED
+  PROTOBUF_NODISCARD std::string* Release(const std::string*, Arena* arena,
+                                          bool donated) {
+    return Release(arena, donated);
+  }
+
+  PROTOBUF_NODISCARD std::string* ReleaseNonDefault(const std::string*,
+                                                    Arena* arena) {
+    return Release();
+  }
+
+  std::string* ReleaseNonDefaultNoArena(const std::string* default_value) {
+    return Release();
+  }
+
+  void Set(const std::string*, ConstStringParam value, Arena* arena,
+           bool donated, uint32_t* donating_states, uint32_t mask,
+           MessageLite* msg) {
+    Set(value, arena, donated, donating_states, mask, msg);
+  }
+
+  void Set(const std::string*, std::string&& value, Arena* arena, bool donated,
+           uint32_t* donating_states, uint32_t mask, MessageLite* msg) {
+    Set(std::move(value), arena, donated, donating_states, mask, msg);
+  }
+
+
+  template <typename FirstParam>
+  void Set(FirstParam, const char* str, ::google::protobuf::Arena* arena, bool donated,
+           uint32_t* donating_states, uint32_t mask, MessageLite* msg) {
+    Set(str, arena, donated, donating_states, mask, msg);
+  }
+
+  template <typename FirstParam>
+  void Set(FirstParam p1, const char* str, size_t size, ::google::protobuf::Arena* arena,
+           bool donated, uint32_t* donating_states, uint32_t mask,
+           MessageLite* msg) {
+    Set(str, size, arena, donated, donating_states, mask, msg);
+  }
+
+  template <typename FirstParam, typename RefWrappedType>
+  void Set(FirstParam p1,
+           std::reference_wrapper<RefWrappedType> const_string_ref,
+           ::google::protobuf::Arena* arena, bool donated, uint32_t* donating_states,
+           uint32_t mask, MessageLite* msg) {
+    Set(const_string_ref, arena, donated, donating_states, mask, msg);
+  }
+
+  void SetBytes(const std::string*, ConstStringParam value, Arena* arena,
+                bool donated, uint32_t* donating_states, uint32_t mask,
+                MessageLite* msg) {
+    Set(value, arena, donated, donating_states, mask, msg);
+  }
+
+
+  void SetBytes(const std::string*, std::string&& value, Arena* arena,
+                bool donated, uint32_t* donating_states, uint32_t mask,
+                MessageLite* msg) {
+    Set(std::move(value), arena, donated, donating_states, mask, msg);
+  }
+
+  template <typename FirstParam>
+  void SetBytes(FirstParam p1, const char* str, ::google::protobuf::Arena* arena,
+                bool donated, uint32_t* donating_states, uint32_t mask,
+                MessageLite* msg) {
+    SetBytes(str, arena, donated, donating_states, mask, msg);
+  }
+
+  template <typename FirstParam>
+  void SetBytes(FirstParam p1, const void* p, size_t size,
+                ::google::protobuf::Arena* arena, bool donated, uint32_t* donating_states,
+                uint32_t mask, MessageLite* msg) {
+    SetBytes(p, size, arena, donated, donating_states, mask, msg);
+  }
+
+  template <typename FirstParam, typename RefWrappedType>
+  void SetBytes(FirstParam p1,
+                std::reference_wrapper<RefWrappedType> const_string_ref,
+                ::google::protobuf::Arena* arena, bool donated, uint32_t* donating_states,
+                uint32_t mask, MessageLite* msg) {
+    SetBytes(const_string_ref.get(), arena, donated, donating_states, mask,
+             msg);
+  }
+
+  void SetNoArena(const std::string*, StringPiece value) {
+    SetNoArena(value);
+  }
+  void SetNoArena(const std::string*, std::string&& value) {
+    SetNoArena(std::move(value));
+  }
+
+  std::string* Mutable(ArenaStringPtr::EmptyDefault, Arena* arena, bool donated,
+                       uint32_t* donating_states, uint32_t mask,
+                       MessageLite* msg) {
+    return Mutable(arena, donated, donating_states, mask, msg);
+  }
+
+  PROTOBUF_NDEBUG_INLINE std::string* MutableNoArenaNoDefault(
+      const std::string* /*default_value*/) {
+    return MutableNoCopy(nullptr);
+  }
+
+#endif  // DEPRECATED_METHODS_TO_BE_DELETED
+
   // Arena-safety semantics: this is guarded by the logic in
   // Swap()/UnsafeArenaSwap() at the message level, so this method is
   // 'unsafe' if called directly.
@@ -258,17 +349,12 @@ class PROTOBUF_EXPORT InlinedStringField {
   void ClearToDefault(const LazyString& default_value, Arena* arena,
                       bool donated);
 
-  // Returns a mutable pointer, but doesn't initialize the string to the
-  // default value.
-  PROTOBUF_NDEBUG_INLINE std::string* MutableNoArenaNoDefault(
-      const std::string* /*default_value*/);
-
   // Generated code / reflection only! Returns a mutable pointer to the string.
   PROTOBUF_NDEBUG_INLINE std::string* UnsafeMutablePointer();
 
   // InlinedStringField doesn't have things like the `default_value` pointer in
   // ArenaStringPtr.
-  static constexpr bool IsDefault()  { return false; }
+  static constexpr bool IsDefault() { return false; }
   static constexpr bool IsDefault(const std::string*) { return false; }
 
  private:
@@ -327,21 +413,11 @@ inline void InlinedStringField::DestroyNoArena(const std::string*) {
   this->~InlinedStringField();
 }
 
-inline std::string* InlinedStringField::ReleaseNonDefaultNoArena(
-    const std::string* /*default_value*/) {
-  // Currently, inlined string field can't have non empty default.
-  auto* released = new std::string();
-  get_mutable()->swap(*released);
-  return released;
-}
-
-inline void InlinedStringField::SetNoArena(const std::string* /*default_value*/,
-                                           StringPiece value) {
+inline void InlinedStringField::SetNoArena(StringPiece value) {
   get_mutable()->assign(value.data(), value.length());
 }
 
-inline void InlinedStringField::SetNoArena(const std::string* /*default_value*/,
-                                           std::string&& value) {
+inline void InlinedStringField::SetNoArena(std::string&& value) {
   get_mutable()->assign(std::move(value));
 }
 
@@ -369,15 +445,84 @@ inline PROTOBUF_NDEBUG_INLINE void InlinedStringField::InternalSwap(
 #endif
 }
 
-inline std::string* InlinedStringField::MutableNoArenaNoDefault(
-    const std::string*) {
-  return get_mutable();
+inline void InlinedStringField::Set(ConstStringParam value, Arena* arena,
+                                    bool donated, uint32_t* /*donating_states*/,
+                                    uint32_t /*mask*/, MessageLite* /*msg*/) {
+  (void)arena;
+  (void)donated;
+  SetNoArena(value);
+}
+
+inline void InlinedStringField::Set(const char* str, ::google::protobuf::Arena* arena,
+                                    bool donated, uint32_t* donating_states,
+                                    uint32_t mask, MessageLite* msg) {
+  Set(ConstStringParam(str), arena, donated, donating_states, mask, msg);
+}
+
+inline void InlinedStringField::Set(const char* str, size_t size,
+                                    ::google::protobuf::Arena* arena, bool donated,
+                                    uint32_t* donating_states, uint32_t mask,
+                                    MessageLite* msg) {
+  Set(ConstStringParam{str, size}, arena, donated, donating_states, mask, msg);
+}
+
+inline void InlinedStringField::SetBytes(ConstStringParam value, Arena* arena,
+                                         bool donated,
+                                         uint32_t* donating_states,
+                                         uint32_t mask, MessageLite* msg) {
+  Set(value, arena, donated, donating_states, mask, msg);
+}
+
+inline void InlinedStringField::SetBytes(std::string&& value, Arena* arena,
+                                         bool donated,
+                                         uint32_t* donating_states,
+                                         uint32_t mask, MessageLite* msg) {
+  Set(std::move(value), arena, donated, donating_states, mask, msg);
+}
+
+inline void InlinedStringField::SetBytes(const char* str,
+                                         ::google::protobuf::Arena* arena, bool donated,
+                                         uint32_t* donating_states,
+                                         uint32_t mask, MessageLite* msg) {
+  Set(str, arena, donated, donating_states, mask, msg);
+}
+
+inline void InlinedStringField::SetBytes(const void* p, size_t size,
+                                         ::google::protobuf::Arena* arena, bool donated,
+                                         uint32_t* donating_states,
+                                         uint32_t mask, MessageLite* msg) {
+  Set(static_cast<const char*>(p), size, arena, donated, donating_states, mask,
+      msg);
+}
+
+template <typename RefWrappedType>
+inline void InlinedStringField::Set(
+    std::reference_wrapper<RefWrappedType> const_string_ref,
+    ::google::protobuf::Arena* arena, bool donated, uint32_t* donating_states,
+    uint32_t mask, MessageLite* msg) {
+  Set(const_string_ref.get(), arena, donated, donating_states, mask, msg);
+}
+
+template <typename RefWrappedType>
+inline void InlinedStringField::SetBytes(
+    std::reference_wrapper<RefWrappedType> const_string_ref,
+    ::google::protobuf::Arena* arena, bool donated, uint32_t* donating_states,
+    uint32_t mask, MessageLite* msg) {
+  Set(const_string_ref.get(), arena, donated, donating_states, mask, msg);
 }
 
 inline std::string* InlinedStringField::UnsafeMutablePointer() {
   return get_mutable();
 }
 
+inline std::string* InlinedStringField::Mutable(std::nullptr_t) {
+  return get_mutable();
+}
+
+inline std::string* InlinedStringField::MutableNoCopy(std::nullptr_t) {
+  return get_mutable();
+}
+
 }  // namespace internal
 }  // namespace protobuf
 }  // namespace google

src/google/protobuf/inlined_string_field_unittest.cc

@@ -35,6 +35,7 @@
 #include <cstring>
 #include <memory>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include <google/protobuf/stubs/logging.h>

src/google/protobuf/map_type_handler.h

@@ -580,12 +580,12 @@ inline bool MapTypeHandler<WireFormatLite::TYPE_MESSAGE, Type>::IsInitialized(
   template <typename Type>                                                    \
   inline void MapTypeHandler<WireFormatLite::TYPE_##FieldType, Type>::Merge(  \
       const MapEntryAccessorType& from, TypeOnMemory* to, Arena* arena) {     \
-    to->Set(&internal::GetEmptyStringAlreadyInited(), from, arena);           \
+    to->Set(from, arena);                                                     \
   }                                                                           \
   template <typename Type>                                                    \
   void MapTypeHandler<WireFormatLite::TYPE_##FieldType, Type>::DeleteNoArena( \
       TypeOnMemory& value) {                                                  \
-    value.DestroyNoArena(&internal::GetEmptyStringAlreadyInited());           \
+    value.Destroy();                                                          \
   }                                                                           \
   template <typename Type>                                                    \
   constexpr auto                                                              \
@@ -598,7 +598,7 @@ inline bool MapTypeHandler<WireFormatLite::TYPE_MESSAGE, Type>::IsInitialized(
                                  Type>::MapEntryAccessorType*                 \
   MapTypeHandler<WireFormatLite::TYPE_##FieldType, Type>::EnsureMutable(      \
       TypeOnMemory* value, Arena* arena) {                                    \
-    return value->Mutable(ArenaStringPtr::EmptyDefault{}, arena);             \
+    return value->Mutable(arena);                                             \
   }                                                                           \
   template <typename Type>                                                    \
   inline const typename MapTypeHandler<WireFormatLite::TYPE_##FieldType,      \

src/google/protobuf/message_lite.cc

@@ -41,7 +41,6 @@
 
 #include <google/protobuf/stubs/logging.h>
 #include <google/protobuf/stubs/common.h>
-#include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/parse_context.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream.h>
@@ -230,7 +229,7 @@ bool MessageLite::MergeFromImpl(io::CodedInputStream* input,
   if (PROTOBUF_PREDICT_FALSE(!ptr)) return false;
   ctx.BackUp(ptr);
   if (!ctx.EndedAtEndOfStream()) {
-    GOOGLE_DCHECK(ctx.LastTag() != 1);  // We can't end on a pushed limit.
+    GOOGLE_DCHECK_NE(ctx.LastTag(), 1);  // We can't end on a pushed limit.
     if (ctx.IsExceedingLimit(ptr)) return false;
     input->SetLastTag(ctx.LastTag());
   } else {

src/google/protobuf/message_unittest.inc

@@ -419,6 +419,29 @@ TEST(MESSAGE_TEST_NAME, ParseStrictlyBoundedStream) {
   TestUtil::ExpectAllFieldsSet(p.child().payload());
 }
 
+TEST(MESSAGE_TEST_NAME, AllSetMethodsOnStringField) {
+  UNITTEST::TestAllTypes msg;
+
+
+  msg.set_optional_string("Asciiz");
+  EXPECT_EQ(msg.optional_string(), "Asciiz");
+
+  msg.set_optional_string("Length delimited", 6);
+  EXPECT_EQ(msg.optional_string(), "Length");
+
+  std::string value = "std::string value 1";
+  msg.set_optional_string(value);
+  EXPECT_EQ(msg.optional_string(), "std::string value 1");
+
+  value = "std::string value 2";
+  msg.set_optional_string(std::cref(value));
+  EXPECT_EQ(msg.optional_string(), "std::string value 2");
+
+  value = "std::string value 3";
+  msg.set_optional_string(std::move(value));
+  EXPECT_EQ(msg.optional_string(), "std::string value 3");
+}
+
 TEST(MESSAGE_TEST_NAME, SuccessAfterParsingFailure) {
   UNITTEST::NestedTestAllTypes o, p, q;
   constexpr int kDepth = 5;

src/google/protobuf/parse_context.cc

@@ -30,7 +30,6 @@
 
 #include <google/protobuf/parse_context.h>
 
-#include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/arenastring.h>
@@ -51,8 +50,8 @@ namespace {
 // Only call if at start of tag.
 bool ParseEndsInSlopRegion(const char* begin, int overrun, int depth) {
   constexpr int kSlopBytes = EpsCopyInputStream::kSlopBytes;
-  GOOGLE_DCHECK(overrun >= 0);
-  GOOGLE_DCHECK(overrun <= kSlopBytes);
+  GOOGLE_DCHECK_GE(overrun, 0);
+  GOOGLE_DCHECK_LE(overrun, kSlopBytes);
   auto ptr = begin + overrun;
   auto end = begin + kSlopBytes;
   while (ptr < end) {
@@ -181,17 +180,17 @@ std::pair<const char*, bool> EpsCopyInputStream::DoneFallback(int overrun,
   // if (ptr < limit_end_) return {ptr, false};
   GOOGLE_DCHECK(limit_end_ == buffer_end_ + (std::min)(0, limit_));
   // At this point we know the following assertion holds.
-  GOOGLE_DCHECK(limit_ > 0);
+  GOOGLE_DCHECK_GT(limit_, 0);
   GOOGLE_DCHECK(limit_end_ == buffer_end_);  // because limit_ > 0
   const char* p;
   do {
     // We are past the end of buffer_end_, in the slop region.
-    GOOGLE_DCHECK(overrun >= 0);
+    GOOGLE_DCHECK_GE(overrun, 0);
     p = NextBuffer(overrun, depth);
     if (p == nullptr) {
       // We are at the end of the stream
       if (PROTOBUF_PREDICT_FALSE(overrun != 0)) return {nullptr, true};
-      GOOGLE_DCHECK(limit_ > 0);
+      GOOGLE_DCHECK_GT(limit_, 0);
       limit_end_ = buffer_end_;
       // Distinguish ending on a pushed limit or ending on end-of-stream.
       SetEndOfStream();

src/google/protobuf/reflection_ops.cc

@@ -423,16 +423,16 @@ void ReflectionOps::FindInitializationErrors(const Message& message,
 
 void GenericSwap(Message* lhs, Message* rhs) {
 #ifndef PROTOBUF_FORCE_COPY_IN_SWAP
-  GOOGLE_DCHECK(Arena::InternalHelper<Message>::GetOwningArena(lhs) !=
-         Arena::InternalHelper<Message>::GetOwningArena(rhs));
-  GOOGLE_DCHECK(Arena::InternalHelper<Message>::GetOwningArena(lhs) != nullptr ||
-         Arena::InternalHelper<Message>::GetOwningArena(rhs) != nullptr);
+  GOOGLE_DCHECK(Arena::InternalGetOwningArena(lhs) !=
+         Arena::InternalGetOwningArena(rhs));
+  GOOGLE_DCHECK(Arena::InternalGetOwningArena(lhs) != nullptr ||
+         Arena::InternalGetOwningArena(rhs) != nullptr);
 #endif  // !PROTOBUF_FORCE_COPY_IN_SWAP
   // At least one of these must have an arena, so make `rhs` point to it.
-  Arena* arena = Arena::InternalHelper<Message>::GetOwningArena(rhs);
+  Arena* arena = Arena::InternalGetOwningArena(rhs);
   if (arena == nullptr) {
     std::swap(lhs, rhs);
-    arena = Arena::InternalHelper<Message>::GetOwningArena(rhs);
+    arena = Arena::InternalGetOwningArena(rhs);
   }
 
   // Improve efficiency by placing the temporary on an arena so that messages

src/google/protobuf/source_context.pb.cc

@@ -97,10 +97,10 @@ SourceContext::SourceContext(const SourceContext& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   file_name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    file_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    file_name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_file_name().empty()) {
-    file_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_file_name(), 
+    file_name_.Set(from._internal_file_name(), 
       GetArenaForAllocation());
   }
   // @@protoc_insertion_point(copy_constructor:google.protobuf.SourceContext)
@@ -109,7 +109,7 @@ SourceContext::SourceContext(const SourceContext& from)
 inline void SourceContext::SharedCtor() {
 file_name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  file_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  file_name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 }
 
@@ -124,7 +124,7 @@ SourceContext::~SourceContext() {
 
 inline void SourceContext::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  file_name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  file_name_.Destroy();
 }
 
 void SourceContext::SetCachedSize(int size) const {
@@ -264,7 +264,6 @@ void SourceContext::InternalSwap(SourceContext* other) {
   auto* rhs_arena = other->GetArenaForAllocation();
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &file_name_, lhs_arena,
       &other->file_name_, rhs_arena
   );

src/google/protobuf/source_context.pb.h

@@ -225,7 +225,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void SourceContext::set_file_name(ArgT0&& arg0, ArgT... args) {
  
- file_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ file_name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.SourceContext.file_name)
 }
 inline std::string* SourceContext::mutable_file_name() {
@@ -238,15 +238,15 @@ inline const std::string& SourceContext::_internal_file_name() const {
 }
 inline void SourceContext::_internal_set_file_name(const std::string& value) {
   
-  file_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  file_name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* SourceContext::_internal_mutable_file_name() {
   
-  return file_name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return file_name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* SourceContext::release_file_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.SourceContext.file_name)
-  return file_name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return file_name_.Release();
 }
 inline void SourceContext::set_allocated_file_name(std::string* file_name) {
   if (file_name != nullptr) {
@@ -254,11 +254,10 @@ inline void SourceContext::set_allocated_file_name(std::string* file_name) {
   } else {
     
   }
-  file_name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), file_name,
-      GetArenaForAllocation());
+  file_name_.SetAllocated(file_name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (file_name_.IsDefault()) {
-    file_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    file_name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.SourceContext.file_name)

src/google/protobuf/struct.pb.cc

@@ -416,7 +416,7 @@ void Value::set_allocated_struct_value(::PROTOBUF_NAMESPACE_ID::Struct* struct_v
   clear_kind();
   if (struct_value) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-      ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<::PROTOBUF_NAMESPACE_ID::Struct>::GetOwningArena(struct_value);
+      ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(struct_value);
     if (message_arena != submessage_arena) {
       struct_value = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(
           message_arena, struct_value, submessage_arena);
@@ -431,7 +431,7 @@ void Value::set_allocated_list_value(::PROTOBUF_NAMESPACE_ID::ListValue* list_va
   clear_kind();
   if (list_value) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-      ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<::PROTOBUF_NAMESPACE_ID::ListValue>::GetOwningArena(list_value);
+      ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(list_value);
     if (message_arena != submessage_arena) {
       list_value = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(
           message_arena, list_value, submessage_arena);
@@ -519,7 +519,7 @@ void Value::clear_kind() {
       break;
     }
     case kStringValue: {
-      kind_.string_value_.Destroy(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+      kind_.string_value_.Destroy();
       break;
     }
     case kBoolValue: {

src/google/protobuf/struct.pb.h

@@ -828,7 +828,7 @@ inline void Value::set_has_string_value() {
 }
 inline void Value::clear_string_value() {
   if (_internal_has_string_value()) {
-    kind_.string_value_.Destroy(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+    kind_.string_value_.Destroy();
     clear_has_kind();
   }
 }
@@ -843,7 +843,7 @@ inline void Value::set_string_value(ArgT0&& arg0, ArgT... args) {
     set_has_string_value();
     kind_.string_value_.InitDefault();
   }
-  kind_.string_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+  kind_.string_value_.Set( static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Value.string_value)
 }
 inline std::string* Value::mutable_string_value() {
@@ -863,7 +863,7 @@ inline void Value::_internal_set_string_value(const std::string& value) {
     set_has_string_value();
     kind_.string_value_.InitDefault();
   }
-  kind_.string_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  kind_.string_value_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Value::_internal_mutable_string_value() {
   if (!_internal_has_string_value()) {
@@ -871,14 +871,13 @@ inline std::string* Value::_internal_mutable_string_value() {
     set_has_string_value();
     kind_.string_value_.InitDefault();
   }
-  return kind_.string_value_.Mutable(
-      ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return kind_.string_value_.Mutable(      GetArenaForAllocation());
 }
 inline std::string* Value::release_string_value() {
   // @@protoc_insertion_point(field_release:google.protobuf.Value.string_value)
   if (_internal_has_string_value()) {
     clear_has_kind();
-    return kind_.string_value_.ReleaseNonDefault(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+    return kind_.string_value_.Release();
   } else {
     return nullptr;
   }

src/google/protobuf/type.pb.cc

@@ -376,10 +376,10 @@ Type::Type(const Type& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_source_context()) {
@@ -394,7 +394,7 @@ Type::Type(const Type& from)
 inline void Type::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&source_context_) - reinterpret_cast<char*>(this)),
@@ -413,7 +413,7 @@ Type::~Type() {
 
 inline void Type::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete source_context_;
 }
 
@@ -707,7 +707,6 @@ void Type::InternalSwap(Type* other) {
   oneofs_.InternalSwap(&other->oneofs_);
   options_.InternalSwap(&other->options_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -744,34 +743,34 @@ Field::Field(const Field& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   type_url_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    type_url_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_type_url().empty()) {
-    type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_type_url(), 
+    type_url_.Set(from._internal_type_url(), 
       GetArenaForAllocation());
   }
   json_name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    json_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    json_name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_json_name().empty()) {
-    json_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_json_name(), 
+    json_name_.Set(from._internal_json_name(), 
       GetArenaForAllocation());
   }
   default_value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    default_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    default_value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_default_value().empty()) {
-    default_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_default_value(), 
+    default_value_.Set(from._internal_default_value(), 
       GetArenaForAllocation());
   }
   ::memcpy(&kind_, &from.kind_,
@@ -783,19 +782,19 @@ Field::Field(const Field& from)
 inline void Field::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 type_url_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  type_url_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 json_name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  json_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  json_name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 default_value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  default_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  default_value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&kind_) - reinterpret_cast<char*>(this)),
@@ -814,10 +813,10 @@ Field::~Field() {
 
 inline void Field::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  type_url_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  json_name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
-  default_value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
+  type_url_.Destroy();
+  json_name_.Destroy();
+  default_value_.Destroy();
 }
 
 void Field::SetCachedSize(int size) const {
@@ -1200,22 +1199,18 @@ void Field::InternalSwap(Field* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   options_.InternalSwap(&other->options_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &type_url_, lhs_arena,
       &other->type_url_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &json_name_, lhs_arena,
       &other->json_name_, rhs_arena
   );
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &default_value_, lhs_arena,
       &other->default_value_, rhs_arena
   );
@@ -1265,10 +1260,10 @@ Enum::Enum(const Enum& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_source_context()) {
@@ -1283,7 +1278,7 @@ Enum::Enum(const Enum& from)
 inline void Enum::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 ::memset(reinterpret_cast<char*>(this) + static_cast<size_t>(
     reinterpret_cast<char*>(&source_context_) - reinterpret_cast<char*>(this)),
@@ -1302,7 +1297,7 @@ Enum::~Enum() {
 
 inline void Enum::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete source_context_;
 }
 
@@ -1560,7 +1555,6 @@ void Enum::InternalSwap(Enum* other) {
   enumvalue_.InternalSwap(&other->enumvalue_);
   options_.InternalSwap(&other->options_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -1597,10 +1591,10 @@ EnumValue::EnumValue(const EnumValue& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   number_ = from.number_;
@@ -1610,7 +1604,7 @@ EnumValue::EnumValue(const EnumValue& from)
 inline void EnumValue::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 number_ = 0;
 }
@@ -1626,7 +1620,7 @@ EnumValue::~EnumValue() {
 
 inline void EnumValue::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
 }
 
 void EnumValue::SetCachedSize(int size) const {
@@ -1820,7 +1814,6 @@ void EnumValue::InternalSwap(EnumValue* other) {
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   options_.InternalSwap(&other->options_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );
@@ -1861,10 +1854,10 @@ Option::Option(const Option& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   name_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_name().empty()) {
-    name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_name(), 
+    name_.Set(from._internal_name(), 
       GetArenaForAllocation());
   }
   if (from._internal_has_value()) {
@@ -1878,7 +1871,7 @@ Option::Option(const Option& from)
 inline void Option::SharedCtor() {
 name_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  name_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 value_ = nullptr;
 }
@@ -1894,7 +1887,7 @@ Option::~Option() {
 
 inline void Option::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  name_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  name_.Destroy();
   if (this != internal_default_instance()) delete value_;
 }
 
@@ -2064,7 +2057,6 @@ void Option::InternalSwap(Option* other) {
   auto* rhs_arena = other->GetArenaForAllocation();
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &name_, lhs_arena,
       &other->name_, rhs_arena
   );

src/google/protobuf/type.pb.h

@@ -1370,7 +1370,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Type::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Type.name)
 }
 inline std::string* Type::mutable_name() {
@@ -1383,15 +1383,15 @@ inline const std::string& Type::_internal_name() const {
 }
 inline void Type::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Type::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Type::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Type.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void Type::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -1399,11 +1399,10 @@ inline void Type::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Type.name)
@@ -1635,8 +1634,7 @@ inline void Type::set_allocated_source_context(::PROTOBUF_NAMESPACE_ID::SourceCo
   }
   if (source_context) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-        ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<
-            ::PROTOBUF_NAMESPACE_ID::MessageLite>::GetOwningArena(
+        ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(
                 reinterpret_cast<::PROTOBUF_NAMESPACE_ID::MessageLite*>(source_context));
     if (message_arena != submessage_arena) {
       source_context = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(
@@ -1746,7 +1744,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Field::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Field.name)
 }
 inline std::string* Field::mutable_name() {
@@ -1759,15 +1757,15 @@ inline const std::string& Field::_internal_name() const {
 }
 inline void Field::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Field::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Field::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Field.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void Field::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -1775,11 +1773,10 @@ inline void Field::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.name)
@@ -1797,7 +1794,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Field::set_type_url(ArgT0&& arg0, ArgT... args) {
  
- type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ type_url_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Field.type_url)
 }
 inline std::string* Field::mutable_type_url() {
@@ -1810,15 +1807,15 @@ inline const std::string& Field::_internal_type_url() const {
 }
 inline void Field::_internal_set_type_url(const std::string& value) {
   
-  type_url_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  type_url_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Field::_internal_mutable_type_url() {
   
-  return type_url_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return type_url_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Field::release_type_url() {
   // @@protoc_insertion_point(field_release:google.protobuf.Field.type_url)
-  return type_url_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return type_url_.Release();
 }
 inline void Field::set_allocated_type_url(std::string* type_url) {
   if (type_url != nullptr) {
@@ -1826,11 +1823,10 @@ inline void Field::set_allocated_type_url(std::string* type_url) {
   } else {
     
   }
-  type_url_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), type_url,
-      GetArenaForAllocation());
+  type_url_.SetAllocated(type_url, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (type_url_.IsDefault()) {
-    type_url_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    type_url_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.type_url)
@@ -1928,7 +1924,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Field::set_json_name(ArgT0&& arg0, ArgT... args) {
  
- json_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ json_name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Field.json_name)
 }
 inline std::string* Field::mutable_json_name() {
@@ -1941,15 +1937,15 @@ inline const std::string& Field::_internal_json_name() const {
 }
 inline void Field::_internal_set_json_name(const std::string& value) {
   
-  json_name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  json_name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Field::_internal_mutable_json_name() {
   
-  return json_name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return json_name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Field::release_json_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Field.json_name)
-  return json_name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return json_name_.Release();
 }
 inline void Field::set_allocated_json_name(std::string* json_name) {
   if (json_name != nullptr) {
@@ -1957,11 +1953,10 @@ inline void Field::set_allocated_json_name(std::string* json_name) {
   } else {
     
   }
-  json_name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), json_name,
-      GetArenaForAllocation());
+  json_name_.SetAllocated(json_name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (json_name_.IsDefault()) {
-    json_name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    json_name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.json_name)
@@ -1979,7 +1974,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Field::set_default_value(ArgT0&& arg0, ArgT... args) {
  
- default_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ default_value_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Field.default_value)
 }
 inline std::string* Field::mutable_default_value() {
@@ -1992,15 +1987,15 @@ inline const std::string& Field::_internal_default_value() const {
 }
 inline void Field::_internal_set_default_value(const std::string& value) {
   
-  default_value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  default_value_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Field::_internal_mutable_default_value() {
   
-  return default_value_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return default_value_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Field::release_default_value() {
   // @@protoc_insertion_point(field_release:google.protobuf.Field.default_value)
-  return default_value_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return default_value_.Release();
 }
 inline void Field::set_allocated_default_value(std::string* default_value) {
   if (default_value != nullptr) {
@@ -2008,11 +2003,10 @@ inline void Field::set_allocated_default_value(std::string* default_value) {
   } else {
     
   }
-  default_value_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), default_value,
-      GetArenaForAllocation());
+  default_value_.SetAllocated(default_value, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (default_value_.IsDefault()) {
-    default_value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    default_value_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.default_value)
@@ -2034,7 +2028,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Enum::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Enum.name)
 }
 inline std::string* Enum::mutable_name() {
@@ -2047,15 +2041,15 @@ inline const std::string& Enum::_internal_name() const {
 }
 inline void Enum::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Enum::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Enum::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Enum.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void Enum::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -2063,11 +2057,10 @@ inline void Enum::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Enum.name)
@@ -2224,8 +2217,7 @@ inline void Enum::set_allocated_source_context(::PROTOBUF_NAMESPACE_ID::SourceCo
   }
   if (source_context) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-        ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<
-            ::PROTOBUF_NAMESPACE_ID::MessageLite>::GetOwningArena(
+        ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(
                 reinterpret_cast<::PROTOBUF_NAMESPACE_ID::MessageLite*>(source_context));
     if (message_arena != submessage_arena) {
       source_context = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(
@@ -2275,7 +2267,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void EnumValue::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.EnumValue.name)
 }
 inline std::string* EnumValue::mutable_name() {
@@ -2288,15 +2280,15 @@ inline const std::string& EnumValue::_internal_name() const {
 }
 inline void EnumValue::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* EnumValue::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* EnumValue::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.EnumValue.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void EnumValue::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -2304,11 +2296,10 @@ inline void EnumValue::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.EnumValue.name)
@@ -2390,7 +2381,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void Option::set_name(ArgT0&& arg0, ArgT... args) {
  
- name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ name_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.Option.name)
 }
 inline std::string* Option::mutable_name() {
@@ -2403,15 +2394,15 @@ inline const std::string& Option::_internal_name() const {
 }
 inline void Option::_internal_set_name(const std::string& value) {
   
-  name_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  name_.Set(value, GetArenaForAllocation());
 }
 inline std::string* Option::_internal_mutable_name() {
   
-  return name_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return name_.Mutable(GetArenaForAllocation());
 }
 inline std::string* Option::release_name() {
   // @@protoc_insertion_point(field_release:google.protobuf.Option.name)
-  return name_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return name_.Release();
 }
 inline void Option::set_allocated_name(std::string* name) {
   if (name != nullptr) {
@@ -2419,11 +2410,10 @@ inline void Option::set_allocated_name(std::string* name) {
   } else {
     
   }
-  name_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), name,
-      GetArenaForAllocation());
+  name_.SetAllocated(name, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (name_.IsDefault()) {
-    name_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    name_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Option.name)
@@ -2500,8 +2490,7 @@ inline void Option::set_allocated_value(::PROTOBUF_NAMESPACE_ID::Any* value) {
   }
   if (value) {
     ::PROTOBUF_NAMESPACE_ID::Arena* submessage_arena =
-        ::PROTOBUF_NAMESPACE_ID::Arena::InternalHelper<
-            ::PROTOBUF_NAMESPACE_ID::MessageLite>::GetOwningArena(
+        ::PROTOBUF_NAMESPACE_ID::Arena::InternalGetOwningArena(
                 reinterpret_cast<::PROTOBUF_NAMESPACE_ID::MessageLite*>(value));
     if (message_arena != submessage_arena) {
       value = ::PROTOBUF_NAMESPACE_ID::internal::GetOwnedMessage(

src/google/protobuf/wire_format_lite.cc

@@ -41,10 +41,10 @@
 
 #include <google/protobuf/stubs/logging.h>
 #include <google/protobuf/stubs/common.h>
-#include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/io/zero_copy_stream_impl_lite.h>
+#include <google/protobuf/stubs/stringprintf.h>
 
 
 // Must be included last.

src/google/protobuf/wrappers.pb.cc

@@ -1492,10 +1492,10 @@ StringValue::StringValue(const StringValue& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_value().empty()) {
-    value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_value(), 
+    value_.Set(from._internal_value(), 
       GetArenaForAllocation());
   }
   // @@protoc_insertion_point(copy_constructor:google.protobuf.StringValue)
@@ -1504,7 +1504,7 @@ StringValue::StringValue(const StringValue& from)
 inline void StringValue::SharedCtor() {
 value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 }
 
@@ -1519,7 +1519,7 @@ StringValue::~StringValue() {
 
 inline void StringValue::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  value_.Destroy();
 }
 
 void StringValue::SetCachedSize(int size) const {
@@ -1659,7 +1659,6 @@ void StringValue::InternalSwap(StringValue* other) {
   auto* rhs_arena = other->GetArenaForAllocation();
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &value_, lhs_arena,
       &other->value_, rhs_arena
   );
@@ -1688,10 +1687,10 @@ BytesValue::BytesValue(const BytesValue& from)
   _internal_metadata_.MergeFrom<::PROTOBUF_NAMESPACE_ID::UnknownFieldSet>(from._internal_metadata_);
   value_.InitDefault();
   #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-    value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    value_.Set("", GetArenaForAllocation());
   #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (!from._internal_value().empty()) {
-    value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, from._internal_value(), 
+    value_.Set(from._internal_value(), 
       GetArenaForAllocation());
   }
   // @@protoc_insertion_point(copy_constructor:google.protobuf.BytesValue)
@@ -1700,7 +1699,7 @@ BytesValue::BytesValue(const BytesValue& from)
 inline void BytesValue::SharedCtor() {
 value_.InitDefault();
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
-  value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+  value_.Set("", GetArenaForAllocation());
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
 }
 
@@ -1715,7 +1714,7 @@ BytesValue::~BytesValue() {
 
 inline void BytesValue::SharedDtor() {
   GOOGLE_DCHECK(GetArenaForAllocation() == nullptr);
-  value_.DestroyNoArena(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited());
+  value_.Destroy();
 }
 
 void BytesValue::SetCachedSize(int size) const {
@@ -1850,7 +1849,6 @@ void BytesValue::InternalSwap(BytesValue* other) {
   auto* rhs_arena = other->GetArenaForAllocation();
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   ::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::InternalSwap(
-      &::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(),
       &value_, lhs_arena,
       &other->value_, rhs_arena
   );

src/google/protobuf/wrappers.pb.h

@@ -1574,7 +1574,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void StringValue::set_value(ArgT0&& arg0, ArgT... args) {
  
- value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ value_.Set(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.StringValue.value)
 }
 inline std::string* StringValue::mutable_value() {
@@ -1587,15 +1587,15 @@ inline const std::string& StringValue::_internal_value() const {
 }
 inline void StringValue::_internal_set_value(const std::string& value) {
   
-  value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  value_.Set(value, GetArenaForAllocation());
 }
 inline std::string* StringValue::_internal_mutable_value() {
   
-  return value_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return value_.Mutable(GetArenaForAllocation());
 }
 inline std::string* StringValue::release_value() {
   // @@protoc_insertion_point(field_release:google.protobuf.StringValue.value)
-  return value_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return value_.Release();
 }
 inline void StringValue::set_allocated_value(std::string* value) {
   if (value != nullptr) {
@@ -1603,11 +1603,10 @@ inline void StringValue::set_allocated_value(std::string* value) {
   } else {
     
   }
-  value_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), value,
-      GetArenaForAllocation());
+  value_.SetAllocated(value, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (value_.IsDefault()) {
-    value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    value_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.StringValue.value)
@@ -1629,7 +1628,7 @@ template <typename ArgT0, typename... ArgT>
 inline PROTOBUF_ALWAYS_INLINE
 void BytesValue::set_value(ArgT0&& arg0, ArgT... args) {
  
- value_.SetBytes(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
+ value_.SetBytes(static_cast<ArgT0 &&>(arg0), args..., GetArenaForAllocation());
   // @@protoc_insertion_point(field_set:google.protobuf.BytesValue.value)
 }
 inline std::string* BytesValue::mutable_value() {
@@ -1642,15 +1641,15 @@ inline const std::string& BytesValue::_internal_value() const {
 }
 inline void BytesValue::_internal_set_value(const std::string& value) {
   
-  value_.Set(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, value, GetArenaForAllocation());
+  value_.Set(value, GetArenaForAllocation());
 }
 inline std::string* BytesValue::_internal_mutable_value() {
   
-  return value_.Mutable(::PROTOBUF_NAMESPACE_ID::internal::ArenaStringPtr::EmptyDefault{}, GetArenaForAllocation());
+  return value_.Mutable(GetArenaForAllocation());
 }
 inline std::string* BytesValue::release_value() {
   // @@protoc_insertion_point(field_release:google.protobuf.BytesValue.value)
-  return value_.Release(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), GetArenaForAllocation());
+  return value_.Release();
 }
 inline void BytesValue::set_allocated_value(std::string* value) {
   if (value != nullptr) {
@@ -1658,11 +1657,10 @@ inline void BytesValue::set_allocated_value(std::string* value) {
   } else {
     
   }
-  value_.SetAllocated(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), value,
-      GetArenaForAllocation());
+  value_.SetAllocated(value, GetArenaForAllocation());
 #ifdef PROTOBUF_FORCE_COPY_DEFAULT_STRING
   if (value_.IsDefault()) {
-    value_.Set(&::PROTOBUF_NAMESPACE_ID::internal::GetEmptyStringAlreadyInited(), "", GetArenaForAllocation());
+    value_.Set("", GetArenaForAllocation());
   }
 #endif // PROTOBUF_FORCE_COPY_DEFAULT_STRING
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.BytesValue.value)