Breaking change: Remove C++ legacy syntax descriptor APIs

PiperOrigin-RevId: 589879506

python/build_targets.bzl

@@ -121,7 +121,6 @@ def build_targets(name):
         deps = [
             ":proto_api",
             "//:protobuf",
-            "//src/google/protobuf:descriptor_legacy",
         ] + select({
             "//conditions:default": [],
             ":use_fast_cpp_protos": ["//external:python_headers"],

src/google/protobuf/BUILD.bazel

@@ -580,20 +580,6 @@ cc_library(
     strip_include_prefix = "/src",
 )
 
-cc_library(
-    name = "descriptor_legacy",
-    hdrs = ["descriptor_legacy.h"],
-    copts = COPTS,
-    linkopts = LINK_OPTS,
-    strip_include_prefix = "/src",
-    visibility = ["//:__subpackages__"],
-    deps = [
-        ":port_def",
-        ":protobuf_nowkt",
-        "@com_google_absl//absl/strings",
-    ],
-)
-
 cc_library(
     name = "descriptor_visitor",
     hdrs = ["descriptor_visitor.h"],
@@ -1043,7 +1029,6 @@ cc_test(
     }),
     deps = [
         ":cc_test_protos",
-        ":descriptor_legacy",
         ":protobuf",
         ":test_textproto",
         "//src/google/protobuf/compiler:importer",
@@ -1339,7 +1324,6 @@ cc_test(
     }),
     deps = [
         ":cc_test_protos",
-        ":descriptor_legacy",
         ":protobuf",
         ":test_util",
         "//src/google/protobuf/stubs",

src/google/protobuf/descriptor.cc

@@ -810,21 +810,6 @@ const char* const FieldDescriptor::kLabelToName[MAX_LABEL + 1] = {
     "repeated",  // LABEL_REPEATED
 };
 
-const char* FileDescriptor::SyntaxName(FileDescriptor::Syntax syntax) {
-  switch (syntax) {
-    case SYNTAX_PROTO2:
-      return "proto2";
-    case SYNTAX_PROTO3:
-      return "proto3";
-    case SYNTAX_EDITIONS:
-      return "editions";
-    case SYNTAX_UNKNOWN:
-      return "unknown";
-  }
-  ABSL_LOG(FATAL) << "can't reach here.";
-  return nullptr;
-}
-
 static const char* const kNonLinkedWeakMessageReplacementName = "google.protobuf.Empty";
 
 #if !defined(_MSC_VER) || (_MSC_VER >= 1900 && _MSC_VER < 1912)
@@ -3802,6 +3787,11 @@ bool FieldDescriptor::legacy_enum_field_treated_as_closed() const {
           enum_type()->is_closed());
 }
 
+bool FieldDescriptor::has_optional_keyword() const {
+  return proto3_optional_ || (file()->edition() == Edition::EDITION_PROTO2 &&
+                              is_optional() && !containing_oneof());
+}
+
 // Location methods ===============================================
 
 bool FileDescriptor::GetSourceLocation(const std::vector<int>& path,
@@ -5070,7 +5060,6 @@ FileDescriptor* DescriptorPool::NewPlaceholderFileWithMutexHeld(
   placeholder->tables_ = &FileDescriptorTables::GetEmptyInstance();
   placeholder->source_code_info_ = &SourceCodeInfo::default_instance();
   placeholder->is_placeholder_ = true;
-  placeholder->syntax_ = FileDescriptor::SYNTAX_UNKNOWN;
   placeholder->finished_building_ = true;
   // All other fields are zero or nullptr.
 
@@ -5682,16 +5671,12 @@ FileDescriptor* DescriptorBuilder::BuildFileImpl(
   // TODO: Report error when the syntax is empty after all the protos
   // have added the syntax statement.
   if (proto.syntax().empty() || proto.syntax() == "proto2") {
-    file_->syntax_ = FileDescriptor::SYNTAX_PROTO2;
     file_->edition_ = Edition::EDITION_PROTO2;
   } else if (proto.syntax() == "proto3") {
-    file_->syntax_ = FileDescriptor::SYNTAX_PROTO3;
     file_->edition_ = Edition::EDITION_PROTO3;
   } else if (proto.syntax() == "editions") {
-    file_->syntax_ = FileDescriptor::SYNTAX_EDITIONS;
     file_->edition_ = proto.edition();
   } else {
-    file_->syntax_ = FileDescriptor::SYNTAX_UNKNOWN;
     file_->edition_ = Edition::EDITION_UNKNOWN;
     AddError(proto.name(), proto, DescriptorPool::ErrorCollector::OTHER, [&] {
       return absl::StrCat("Unrecognized syntax: ", proto.syntax());

src/google/protobuf/descriptor.h

@@ -1856,35 +1856,9 @@ class PROTOBUF_EXPORT FileDescriptor : private internal::SymbolBase {
   // descriptor.proto, and any available extensions of that message.
   const FileOptions& options() const;
 
- private:
-  // With the upcoming release of editions, syntax should not be used for
-  // business logic.  Instead, the various feature helpers defined in this file
-  // should be used to query more targeted behaviors.  For example:
-  // has_presence, is_closed, requires_utf8_validation.
-  enum Syntax
-#ifndef SWIG
-      : int
-#endif  // !SWIG
-  {
-    SYNTAX_UNKNOWN = 0,
-    SYNTAX_PROTO2 = 2,
-    SYNTAX_PROTO3 = 3,
-    SYNTAX_EDITIONS = 99,
-  };
-  PROTOBUF_IGNORE_DEPRECATION_START
-  Syntax syntax() const;
-  PROTOBUF_IGNORE_DEPRECATION_STOP
-
-  // Define a visibility-restricted wrapper for internal use until the migration
-  // is complete.
-  friend class FileDescriptorLegacy;
-
-  PROTOBUF_IGNORE_DEPRECATION_START
-  static const char* SyntaxName(Syntax syntax);
-  PROTOBUF_IGNORE_DEPRECATION_STOP
-
  public:
-  // Returns EDITION_UNKNOWN if syntax() is not SYNTAX_EDITIONS.
+  // Returns edition of this file.  For legacy proto2/proto3 files, special
+  // EDITION_PROTO2 and EDITION_PROTO3 values are used.
   Edition edition() const;
 
   // Find a top-level message type by name (not full_name).  Returns nullptr if
@@ -1920,7 +1894,7 @@ class PROTOBUF_EXPORT FileDescriptor : private internal::SymbolBase {
   // Fill the json_name field of FieldDescriptorProto for all fields. Can only
   // be called after CopyTo().
   void CopyJsonNameTo(FileDescriptorProto* proto) const;
-  // Fills in the file-level settings of this file (e.g. syntax, package,
+  // Fills in the file-level settings of this file (e.g. edition, package,
   // file options) to `proto`.
   void CopyHeadingTo(FileDescriptorProto* proto) const;
 
@@ -1962,8 +1936,6 @@ class PROTOBUF_EXPORT FileDescriptor : private internal::SymbolBase {
   // that type accessor functions that can possibly build a dependent file
   // aren't called during the process of building the file.
   bool finished_building_;
-  // Actually a `Syntax` but stored as uint8_t to save space.
-  uint8_t syntax_;
   // This one is here to fill the padding.
   int extension_count_;
 
@@ -2725,19 +2697,9 @@ inline bool FieldDescriptor::is_map() const {
   return type() == TYPE_MESSAGE && is_map_message_type();
 }
 
-inline bool FieldDescriptor::has_optional_keyword() const {
-  PROTOBUF_IGNORE_DEPRECATION_START
-  return proto3_optional_ ||
-         (file()->syntax() == FileDescriptor::SYNTAX_PROTO2 && is_optional() &&
-          !containing_oneof());
-  PROTOBUF_IGNORE_DEPRECATION_STOP
-}
-
 inline const OneofDescriptor* FieldDescriptor::real_containing_oneof() const {
-  PROTOBUF_IGNORE_DEPRECATION_START
   auto* oneof = containing_oneof();
   return oneof && !oneof->is_synthetic() ? oneof : nullptr;
-  PROTOBUF_IGNORE_DEPRECATION_STOP
 }
 
 // To save space, index() is computed by looking at the descriptor's position
@@ -2844,12 +2806,6 @@ inline const FileDescriptor* FileDescriptor::weak_dependency(int index) const {
   return dependency(weak_dependencies_[index]);
 }
 
-PROTOBUF_IGNORE_DEPRECATION_START
-inline FileDescriptor::Syntax FileDescriptor::syntax() const {
-  return static_cast<Syntax>(syntax_);
-}
-PROTOBUF_IGNORE_DEPRECATION_STOP
-
 namespace internal {
 
 // FieldRange(desc) provides an iterable range for the fields of a