When not in custom vtable mode, strip the initializer code via prepro…

…cessor.

The noop code was causing big .proto files to time out even though it had no
effect in the compilation after optimizing.

We tried avoiding the extra complexity of preprocessor checks on each use, but
it seems necessary for now.

PiperOrigin-RevId: 642691974

src/google/protobuf/arena_unittest.cc

@@ -182,20 +182,21 @@ void TestCtorAndDtorTraits(std::vector<absl::string_view> def,
       : std::conditional_t<arena_ctor, ArenaCtorBase, EmptyBase<0>>,
         std::conditional_t<arena_dtor, ArenaDtorBase, EmptyBase<1>>,
         Message {
-    TraitsProber() : Message(nullptr) { actions.push_back("()"); }
-    TraitsProber(const TraitsProber&) : Message(nullptr) {
+    TraitsProber() : Message(nullptr, nullptr) { actions.push_back("()"); }
+    TraitsProber(const TraitsProber&) : Message(nullptr, nullptr) {
       actions.push_back("(const T&)");
     }
-    explicit TraitsProber(int) : Message(nullptr) {
+    explicit TraitsProber(int) : Message(nullptr, nullptr) {
       actions.push_back("(int)");
     }
-    explicit TraitsProber(Arena* arena) : Message(nullptr) {
+    explicit TraitsProber(Arena* arena) : Message(nullptr, nullptr) {
       actions.push_back("(Arena)");
     }
-    TraitsProber(Arena* arena, const TraitsProber&) : Message(nullptr) {
+    TraitsProber(Arena* arena, const TraitsProber&)
+        : Message(nullptr, nullptr) {
       actions.push_back("(Arena, const T&)");
     }
-    TraitsProber(Arena* arena, int) : Message(nullptr) {
+    TraitsProber(Arena* arena, int) : Message(nullptr, nullptr) {
       actions.push_back("(Arena, int)");
     }
     ~TraitsProber() { actions.push_back("~()"); }
@@ -519,9 +520,12 @@ class DispatcherTestProto : public Message {
   using InternalArenaConstructable_ = void;
   using DestructorSkippable_ = void;
   // For the test below to construct.
-  explicit DispatcherTestProto(absl::in_place_t) : Message(nullptr) {}
-  explicit DispatcherTestProto(Arena*) : Message(nullptr) { ABSL_LOG(FATAL); }
-  DispatcherTestProto(Arena*, const DispatcherTestProto&) : Message(nullptr) {
+  explicit DispatcherTestProto(absl::in_place_t) : Message(nullptr, nullptr) {}
+  explicit DispatcherTestProto(Arena*) : Message(nullptr, nullptr) {
+    ABSL_LOG(FATAL);
+  }
+  DispatcherTestProto(Arena*, const DispatcherTestProto&)
+      : Message(nullptr, nullptr) {
     ABSL_LOG(FATAL);
   }
   DispatcherTestProto* New(Arena*) const PROTOBUF_FINAL { ABSL_LOG(FATAL); }

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

@@ -2143,9 +2143,14 @@ void MessageGenerator::GenerateClassMethods(io::Printer* p) {
               }},
              {"class_data", [&] { GenerateClassData(p); }}},
             R"cc(
+#if defined(PROTOBUF_CUSTOM_VTABLE)
               $classname$::$classname$() : SuperType(_class_data_.base()) {}
               $classname$::$classname$(::$proto_ns$::Arena* arena)
                   : SuperType(arena, _class_data_.base()) {}
+#else   // PROTOBUF_CUSTOM_VTABLE
+              $classname$::$classname$() : SuperType() {}
+              $classname$::$classname$(::$proto_ns$::Arena* arena) : SuperType(arena) {}
+#endif  // PROTOBUF_CUSTOM_VTABLE
               $annotate_accessors$;
               $verify$;
               $class_data$;
@@ -2859,7 +2864,12 @@ void MessageGenerator::GenerateConstexprConstructor(io::Printer* p) {
               //~ gcc 12 (warning in gcc 13).
               template <typename>
               $constexpr$ $classname$::$classname$(::_pbi::ConstantInitialized)
-                  : $base$(_class_data_.base()) {}
+#if defined(PROTOBUF_CUSTOM_VTABLE)
+                  : $base$(_class_data_.base()){}
+#else   // PROTOBUF_CUSTOM_VTABLE
+                  : $base$() {
+              }
+#endif  // PROTOBUF_CUSTOM_VTABLE
             )cc");
     return;
   }
@@ -2881,8 +2891,13 @@ void MessageGenerator::GenerateConstexprConstructor(io::Printer* p) {
       R"cc(
         template <typename>
         $constexpr$ $classname$::$classname$(::_pbi::ConstantInitialized)
+#if defined(PROTOBUF_CUSTOM_VTABLE)
             : $superclass$(_class_data_.base()),
-              _impl_(::_pbi::ConstantInitialized()) {}
+#else   // PROTOBUF_CUSTOM_VTABLE
+            : $superclass$(),
+#endif  // PROTOBUF_CUSTOM_VTABLE
+              _impl_(::_pbi::ConstantInitialized()) {
+        }
       )cc");
 }
 
@@ -3145,7 +3160,11 @@ void MessageGenerator::GenerateArenaEnabledCopyConstructor(io::Printer* p) {
                 ::$proto_ns$::Arena* arena,
                 //~ force alignment
                 const $classname$& from)
+#if defined(PROTOBUF_CUSTOM_VTABLE)
                 : $superclass$(arena, _class_data_.base()) {
+#else   // PROTOBUF_CUSTOM_VTABLE
+                : $superclass$(arena) {
+#endif  // PROTOBUF_CUSTOM_VTABLE
               $classname$* const _this = this;
               (void)_this;
               _internal_metadata_.MergeFrom<$unknown_fields_type$>(
@@ -3191,7 +3210,11 @@ void MessageGenerator::GenerateStructors(io::Printer* p) {
       },
       R"cc(
         $classname$::$classname$(::$proto_ns$::Arena* arena)
+#if defined(PROTOBUF_CUSTOM_VTABLE)
             : $superclass$(arena, _class_data_.base()) {
+#else   // PROTOBUF_CUSTOM_VTABLE
+            : $superclass$(arena) {
+#endif  // PROTOBUF_CUSTOM_VTABLE
           $ctor_body$;
           // @@protoc_insertion_point(arena_constructor:$full_name$)
         }
@@ -3733,9 +3756,11 @@ void MessageGenerator::GenerateClassData(io::Printer* p) {
                       $on_demand_register_arena_dtor$,
                       $is_initialized$,
                       &$classname$::MergeImpl,
+#if defined(PROTOBUF_CUSTOM_VTABLE)
                       $superclass$::GetDeleteImpl<$classname$>(),
                       $superclass$::GetNewImpl<$classname$>(),
                       $custom_vtable_methods$,
+#endif  // PROTOBUF_CUSTOM_VTABLE
                       PROTOBUF_FIELD_OFFSET($classname$, $cached_size$),
                       false,
                   },
@@ -3768,9 +3793,11 @@ void MessageGenerator::GenerateClassData(io::Printer* p) {
                       $on_demand_register_arena_dtor$,
                       $is_initialized$,
                       &$classname$::MergeImpl,
+#if defined(PROTOBUF_CUSTOM_VTABLE)
                       $superclass$::GetDeleteImpl<$classname$>(),
                       $superclass$::GetNewImpl<$classname$>(),
                       $custom_vtable_methods$,
+#endif  // PROTOBUF_CUSTOM_VTABLE
                       PROTOBUF_FIELD_OFFSET($classname$, $cached_size$),
                       true,
                   },