[preferences] Compile out loop() when flash_write_interval is non-zero (#14943)

esphome/components/preferences/__init__.py

@@ -21,5 +21,9 @@ CONFIG_SCHEMA = cv.Schema(
 @coroutine_with_priority(CoroPriority.PREFERENCES)
 async def to_code(config):
     var = cg.new_Pvariable(config[CONF_ID])
-    cg.add(var.set_write_interval(config[CONF_FLASH_WRITE_INTERVAL]))
+    write_interval = config[CONF_FLASH_WRITE_INTERVAL]
+    if write_interval.total_milliseconds == 0:
+        cg.add_define("USE_PREFERENCES_SYNC_EVERY_LOOP")
+    else:
+        cg.add(var.set_write_interval(write_interval))
     await cg.register_component(var, config)

esphome/components/preferences/syncer.h

@@ -8,24 +8,21 @@ namespace preferences {
 
 class IntervalSyncer final : public Component {
  public:
+#ifdef USE_PREFERENCES_SYNC_EVERY_LOOP
+  void loop() override { global_preferences->sync(); }
+#else
   void set_write_interval(uint32_t write_interval) { this->write_interval_ = write_interval; }
   void setup() override {
-    if (this->write_interval_ != 0) {
-      set_interval(this->write_interval_, []() { global_preferences->sync(); });
-      // When using interval-based syncing, we don't need the loop
-      this->disable_loop();
-    }
-  }
-  void loop() override {
-    if (this->write_interval_ == 0) {
-      global_preferences->sync();
-    }
+    this->set_interval(this->write_interval_, []() { global_preferences->sync(); });
   }
+#endif
   void on_shutdown() override { global_preferences->sync(); }
   float get_setup_priority() const override { return setup_priority::BUS; }
 
+#ifndef USE_PREFERENCES_SYNC_EVERY_LOOP
  protected:
   uint32_t write_interval_{60000};
+#endif
 };
 
 }  // namespace preferences

esphome/core/defines.h

@@ -118,6 +118,7 @@
 #define USE_NUMBER
 #define USE_OUTPUT
 #define USE_POWER_SUPPLY
+#define USE_PREFERENCES_SYNC_EVERY_LOOP
 #define USE_QR_CODE
 #define USE_SAFE_MODE_CALLBACK
 #define USE_SELECT