From f3c175ab39288beb7b95d1c2c0e1735c1a16edd0 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sat, 28 Feb 2026 16:29:19 -1000
Subject: [PATCH] [api] Remove virtual destructor from ProtoMessage
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API protobuf messages are never deleted through base class pointers —
they are always stack-allocated and passed by reference. The virtual
destructor occupies 2 vtable slots (complete + deleting destructor)
on 32-bit platforms using the Itanium ABI, costing 8 bytes per vtable.

With 122 message classes, removing the virtual destructor saves
~976 bytes of flash. Each vtable shrinks from 24 bytes to 16 bytes.
---
 esphome/components/api/api_pb2.h    | 3 ---
 esphome/components/api/proto.h      | 3 ++-
 script/api_protobuf/api_protobuf.py | 3 +--
 3 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 22dc3de995d..2d4bdfbaece 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -316,7 +316,6 @@ enum ZWaveProxyRequestType : uint32_t {
 
 class InfoResponseProtoMessage : public ProtoMessage {
  public:
-  ~InfoResponseProtoMessage() override = default;
   StringRef object_id{};
   uint32_t key{0};
   StringRef name{};
@@ -334,7 +333,6 @@ class InfoResponseProtoMessage : public ProtoMessage {
 
 class StateResponseProtoMessage : public ProtoMessage {
  public:
-  ~StateResponseProtoMessage() override = default;
   uint32_t key{0};
 #ifdef USE_DEVICES
   uint32_t device_id{0};
@@ -345,7 +343,6 @@ class StateResponseProtoMessage : public ProtoMessage {
 
 class CommandProtoMessage : public ProtoDecodableMessage {
  public:
-  ~CommandProtoMessage() override = default;
   uint32_t key{0};
 #ifdef USE_DEVICES
   uint32_t device_id{0};
diff --git a/esphome/components/api/proto.h b/esphome/components/api/proto.h
index c34f7744e6b..ac6e707ee75 100644
--- a/esphome/components/api/proto.h
+++ b/esphome/components/api/proto.h
@@ -452,7 +452,8 @@ class DumpBuffer {
 
 class ProtoMessage {
  public:
-  virtual ~ProtoMessage() = default;
+  // No virtual destructor - messages are never deleted polymorphically
+  // (all are stack-allocated and used through references)
   // Default implementation for messages with no fields
   virtual void encode(ProtoWriteBuffer &buffer) const {}
   // Default implementation for messages with no fields
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 350947a8d69..081d5d23a88 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -2473,8 +2473,7 @@ def build_base_class(
     out = f"class {base_class_name} : public {parent_class} {{\n"
     out += " public:\n"
 
-    # Add destructor with override
-    public_content.insert(0, f"~{base_class_name}() override = default;")
+    # No virtual destructor - messages are never deleted polymorphically
 
     # Base classes don't implement encode/decode/calculate_size
     # Derived classes handle these with their specific field numbers