[mqtt] Use a numeric scheduler id for the deferred state publish (#20359)

esphome/components/mqtt/mqtt_component.h

@@ -273,6 +273,8 @@ class MQTTComponent : public Component {
   void subscribe_json(const std::string &topic, const mqtt_json_callback_t &callback, uint8_t qos = 0);
 
  protected:
+  static constexpr uint32_t SEND_DEFER_ID = 0;
+
   /// Helper method to get the discovery topic for this component into a buffer.
   StringRef get_discovery_topic_to_(std::span<char, MQTT_DISCOVERY_TOPIC_MAX_LEN> buf,
                                     const MQTTDiscoveryInfo &discovery_info) const;

esphome/components/mqtt/mqtt_fan.cpp

@@ -121,7 +121,7 @@ void MQTTFanComponent::setup() {
                     });
   }
 
-  this->state_->add_on_state_callback([this]() { this->defer("send", [this]() { this->publish_state(); }); });
+  this->state_->add_on_state_callback([this]() { this->defer(SEND_DEFER_ID, [this]() { this->publish_state(); }); });
 }
 
 void MQTTFanComponent::dump_config() {

esphome/components/mqtt/mqtt_light.cpp

@@ -28,7 +28,7 @@ void MQTTJSONLightComponent::setup() {
 }
 
 void MQTTJSONLightComponent::on_light_remote_values_update() {
-  this->defer("send", [this]() { this->publish_state_(); });
+  this->defer(SEND_DEFER_ID, [this]() { this->publish_state_(); });
 }
 
 MQTTJSONLightComponent::MQTTJSONLightComponent(LightState *state) : state_(state) {}

esphome/components/mqtt/mqtt_lock.cpp

@@ -29,7 +29,7 @@ void MQTTLockComponent::setup() {
     }
   });
   this->lock_->add_on_state_callback(
-      [this](LockState /*state*/) { this->defer("send", [this]() { this->publish_state(); }); });
+      [this](LockState /*state*/) { this->defer(SEND_DEFER_ID, [this]() { this->publish_state(); }); });
 }
 void MQTTLockComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "MQTT Lock '%s': ", this->lock_->get_name().c_str());

esphome/components/mqtt/mqtt_switch.cpp

@@ -34,7 +34,7 @@ void MQTTSwitchComponent::setup() {
     }
   });
   this->switch_->add_on_state_callback(
-      [this](bool enabled) { this->defer("send", [this, enabled]() { this->publish_state(enabled); }); });
+      [this](bool enabled) { this->defer(SEND_DEFER_ID, [this, enabled]() { this->publish_state(enabled); }); });
 }
 void MQTTSwitchComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "MQTT Switch '%s': ", this->switch_->get_name().c_str());

esphome/components/mqtt/mqtt_update.cpp

@@ -24,7 +24,7 @@ void MQTTUpdateComponent::setup() {
     }
   });
 
-  this->update_->add_on_state_callback([this]() { this->defer("send", [this]() { this->publish_state(); }); });
+  this->update_->add_on_state_callback([this]() { this->defer(SEND_DEFER_ID, [this]() { this->publish_state(); }); });
 }
 
 bool MQTTUpdateComponent::publish_state() {