Breaking change: Remove MutableRepeatedFieldRef::Reserve() in reflection (roll forward)

An upcoming performance improvement in RepeatedPtrField is incompatible with this API. The improvement is projected to accelerate repeated access to the elements of `RepeatedPtrField`, in particular and especially sequential access.

PA: https://protobuf.dev/news/2024-12-13/
PiperOrigin-RevId: 708439051

Author: protobuf-github-bot

src/google/protobuf/reflection.h

@@ -97,9 +97,6 @@ class MutableRepeatedFieldRef<
   }
   void Add(const T& value) const { accessor_->template Add<T>(data_, value); }
   void RemoveLast() const { accessor_->RemoveLast(data_); }
-  // TODO: Remove.
-  ABSL_DEPRECATED("Do not use. Will be removed in a future release.")
-  void Reserve(int size) const { accessor_->Reserve(data_, size); }
   void SwapElements(int index1, int index2) const {
     accessor_->SwapElements(data_, index1, index2);
   }
@@ -218,9 +215,6 @@ class MutableRepeatedFieldRef<
   }
   void Add(const T& value) const { accessor_->Add(data_, &value); }
   void RemoveLast() const { accessor_->RemoveLast(data_); }
-  // TODO: Remove.
-  ABSL_DEPRECATED("Do not use. Will be removed in a future release.")
-  void Reserve(int size) const { accessor_->Reserve(data_, size); }
   void SwapElements(int index1, int index2) const {
     accessor_->SwapElements(data_, index1, index2);
   }
@@ -308,9 +302,6 @@ class PROTOBUF_EXPORT RepeatedFieldAccessor {
   virtual void Set(Field* data, int index, const Value* value) const = 0;
   virtual void Add(Field* data, const Value* value) const = 0;
   virtual void RemoveLast(Field* data) const = 0;
-  // TODO: Remove.
-  ABSL_DEPRECATED("Do not use. Will be removed in a future release.")
-  virtual void Reserve(Field* data, int size) const = 0;
   virtual void SwapElements(Field* data, int index1, int index2) const = 0;
   virtual void Swap(Field* data, const RepeatedFieldAccessor* other_mutator,
                     Field* other_data) const = 0;

src/google/protobuf/reflection_internal.h

@@ -93,10 +93,6 @@ class RepeatedFieldWrapper : public RandomAccessRepeatedFieldAccessor {
   void RemoveLast(Field* data) const override {
     MutableRepeatedField(data)->RemoveLast();
   }
-  // TODO: Remove.
-  void Reserve(Field* data, int size) const override {
-    MutableRepeatedField(data)->Reserve(size);
-  }
   void SwapElements(Field* data, int index1, int index2) const override {
     MutableRepeatedField(data)->SwapElements(index1, index2);
   }
@@ -153,10 +149,6 @@ class RepeatedPtrFieldWrapper : public RandomAccessRepeatedFieldAccessor {
   void RemoveLast(Field* data) const override {
     MutableRepeatedField(data)->RemoveLast();
   }
-  // TODO: Remove.
-  void Reserve(Field* data, int size) const override {
-    MutableRepeatedField(data)->Reserve(size);
-  }
   void SwapElements(Field* data, int index1, int index2) const override {
     MutableRepeatedField(data)->SwapElements(index1, index2);
   }
@@ -220,9 +212,6 @@ class MapFieldAccessor final : public RandomAccessRepeatedFieldAccessor {
   void RemoveLast(Field* data) const override {
     MutableRepeatedField(data)->RemoveLast();
   }
-  void Reserve(Field* data, int size) const override {
-    MutableRepeatedField(data)->Reserve(size);
-  }
   void SwapElements(Field* data, int index1, int index2) const override {
     MutableRepeatedField(data)->SwapElements(index1, index2);
   }

src/google/protobuf/repeated_field_reflection_unittest.inc

@@ -339,12 +339,6 @@ TEST(REFLECTION_TEST, RepeatedFieldRefForRegularFields) {
   }
   EXPECT_EQ(10, index);
 
-  // Test MutableRepeatedFieldRef::Reserve()
-  mrf_int32.Reserve(mrf_int32.size() + 1);
-  mrf_double.Reserve(mrf_double.size() + 1);
-  mrf_string.Reserve(mrf_string.size() + 1);
-  mrf_foreign_message.Reserve(mrf_foreign_message.size() + 1);
-
   // Test MutableRepeatedFieldRef::Add()
   mrf_int32.Add(1234);
   mrf_double.Add(1234.0);