[core] Optimize DelayAction for no-argument case using if constexpr

esphome/components/api/user_services.h

@@ -51,14 +51,13 @@ template<typename... Ts> class UserServiceBase : public UserServiceDescriptor {
       return false;
     if (req.args.size() != sizeof...(Ts))
       return false;
-    this->execute_(req.args, std::make_index_sequence<sizeof...(Ts)>{});
+    this->execute_(req.args, typename gens<sizeof...(Ts)>::type());
     return true;
   }
 
  protected:
   virtual void execute(Ts... x) = 0;
-  template<typename ArgsContainer, size_t... S>
-  void execute_(const ArgsContainer &args, std::index_sequence<S...> type) {
+  template<typename ArgsContainer, int... S> void execute_(const ArgsContainer &args, seq<S...> type) {
     this->execute((get_execute_arg_value<Ts>(args[S]))...);
   }
 
@@ -96,14 +95,13 @@ template<typename... Ts> class UserServiceDynamic : public UserServiceDescriptor
       return false;
     if (req.args.size() != sizeof...(Ts))
       return false;
-    this->execute_(req.args, std::make_index_sequence<sizeof...(Ts)>{});
+    this->execute_(req.args, typename gens<sizeof...(Ts)>::type());
     return true;
   }
 
  protected:
   virtual void execute(Ts... x) = 0;
-  template<typename ArgsContainer, size_t... S>
-  void execute_(const ArgsContainer &args, std::index_sequence<S...> type) {
+  template<typename ArgsContainer, int... S> void execute_(const ArgsContainer &args, seq<S...> type) {
     this->execute((get_execute_arg_value<Ts>(args[S]))...);
   }
 

esphome/components/script/script.h

@@ -46,14 +46,14 @@ template<typename... Ts> class Script : public ScriptLogger, public Trigger<Ts..
 
   // execute this script using a tuple that contains the arguments
   void execute_tuple(const std::tuple<Ts...> &tuple) {
-    this->execute_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
+    this->execute_tuple_(tuple, typename gens<sizeof...(Ts)>::type());
   }
 
   // Internal function to give scripts readable names.
   void set_name(const LogString *name) { name_ = name; }
 
  protected:
-  template<size_t... S> void execute_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void execute_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->execute(std::get<S>(tuple)...);
   }
 
@@ -157,7 +157,7 @@ template<typename... Ts> class QueueingScript : public Script<Ts...>, public Com
       const size_t queue_capacity = static_cast<size_t>(this->max_runs_ - 1);
       auto tuple_ptr = std::move(this->var_queue_[this->queue_front_]);
       this->queue_front_ = (this->queue_front_ + 1) % queue_capacity;
-      this->trigger_tuple_(*tuple_ptr, std::make_index_sequence<sizeof...(Ts)>{});
+      this->trigger_tuple_(*tuple_ptr, typename gens<sizeof...(Ts)>::type());
     }
   }
 
@@ -174,7 +174,7 @@ template<typename... Ts> class QueueingScript : public Script<Ts...>, public Com
     }
   }
 
-  template<size_t... S> void trigger_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void trigger_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->trigger(std::get<S>(tuple)...);
   }
 
@@ -305,7 +305,7 @@ template<class C, typename... Ts> class ScriptWaitAction : public Action<Ts...>,
 
     while (!this->param_queue_.empty()) {
       auto &params = this->param_queue_.front();
-      this->play_next_tuple_(params, std::make_index_sequence<sizeof...(Ts)>{});
+      this->play_next_tuple_(params, typename gens<sizeof...(Ts)>::type());
       this->param_queue_.pop_front();
     }
     // Queue is now empty - disable loop until next play_complex
@@ -321,7 +321,7 @@ template<class C, typename... Ts> class ScriptWaitAction : public Action<Ts...>,
   }
 
  protected:
-  template<size_t... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->play_next_(std::get<S>(tuple)...);
   }
 

esphome/core/automation.h

@@ -11,26 +11,10 @@
 
 namespace esphome {
 
-// C++20 std::index_sequence is now used for tuple unpacking
-// Legacy seq<>/gens<> pattern deprecated but kept for backwards compatibility
 // https://stackoverflow.com/questions/7858817/unpacking-a-tuple-to-call-a-matching-function-pointer/7858971#7858971
-// Remove before 2026.6.0
-// NOLINTBEGIN(readability-identifier-naming)
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-#endif
-
-template<int...> struct ESPDEPRECATED("Use std::index_sequence instead. Removed in 2026.6.0", "2025.12.0") seq {};
-template<int N, int... S>
-struct ESPDEPRECATED("Use std::make_index_sequence instead. Removed in 2026.6.0", "2025.12.0") gens
-    : gens<N - 1, N - 1, S...> {};
-template<int... S> struct gens<0, S...> { using type = seq<S...>; };
-
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
-// NOLINTEND(readability-identifier-naming)
+template<int...> struct seq {};                                       // NOLINT
+template<int N, int... S> struct gens : gens<N - 1, N - 1, S...> {};  // NOLINT
+template<int... S> struct gens<0, S...> { using type = seq<S...>; };  // NOLINT
 
 #define TEMPLATABLE_VALUE_(type, name) \
  protected: \
@@ -168,11 +152,11 @@ template<typename... Ts> class Condition {
 
   /// Call check with a tuple of values as parameter.
   bool check_tuple(const std::tuple<Ts...> &tuple) {
-    return this->check_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
+    return this->check_tuple_(tuple, typename gens<sizeof...(Ts)>::type());
   }
 
  protected:
-  template<size_t... S> bool check_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> bool check_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     return this->check(std::get<S>(tuple)...);
   }
 };
@@ -247,11 +231,11 @@ template<typename... Ts> class Action {
       }
     }
   }
-  template<size_t... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->play_next_(std::get<S>(tuple)...);
   }
   void play_next_tuple_(const std::tuple<Ts...> &tuple) {
-    this->play_next_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
+    this->play_next_tuple_(tuple, typename gens<sizeof...(Ts)>::type());
   }
 
   virtual void stop() {}
@@ -293,9 +277,7 @@ template<typename... Ts> class ActionList {
     if (this->actions_begin_ != nullptr)
       this->actions_begin_->play_complex(x...);
   }
-  void play_tuple(const std::tuple<Ts...> &tuple) {
-    this->play_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
-  }
+  void play_tuple(const std::tuple<Ts...> &tuple) { this->play_tuple_(tuple, typename gens<sizeof...(Ts)>::type()); }
   void stop() {
     if (this->actions_begin_ != nullptr)
       this->actions_begin_->stop_complex();
@@ -316,7 +298,7 @@ template<typename... Ts> class ActionList {
   }
 
  protected:
-  template<size_t... S> void play_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void play_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->play(std::get<S>(tuple)...);
   }
 

esphome/core/base_automation.h

@@ -178,7 +178,6 @@ template<typename... Ts> class DelayAction : public Action<Ts...>, public Compon
   TEMPLATABLE_VALUE(uint32_t, delay)
 
   void play_complex(const Ts &...x) override {
-    auto f = std::bind(&DelayAction<Ts...>::play_next_, this, x...);
     this->num_running_++;
 
     // If num_running_ > 1, we have multiple instances running in parallel
@@ -187,9 +186,22 @@ template<typename... Ts> class DelayAction : public Action<Ts...>, public Compon
     // WARNING: This can accumulate delays if scripts are triggered faster than they complete!
     // Users should set max_runs on parallel scripts to limit concurrent executions.
     // Issue #10264: This is a workaround for parallel script delays interfering with each other.
-    App.scheduler.set_timer_common_(this, Scheduler::SchedulerItem::TIMEOUT,
-                                    /* is_static_string= */ true, "delay", this->delay_.value(x...), std::move(f),
-                                    /* is_retry= */ false, /* skip_cancel= */ this->num_running_ > 1);
+
+    // Optimization: For no-argument delays (most common case), use direct lambda
+    // instead of std::bind to avoid bind overhead (~16 bytes heap + faster execution)
+    if constexpr (sizeof...(Ts) == 0) {
+      App.scheduler.set_timer_common_(
+          this, Scheduler::SchedulerItem::TIMEOUT,
+          /* is_static_string= */ true, "delay", this->delay_.value(), [this]() { this->play_next_(); },
+          /* is_retry= */ false, /* skip_cancel= */ this->num_running_ > 1);
+    } else {
+      // For delays with arguments, use std::bind to preserve argument values
+      // Arguments must be copied because original references may be invalid after delay
+      auto f = std::bind(&DelayAction<Ts...>::play_next_, this, x...);
+      App.scheduler.set_timer_common_(this, Scheduler::SchedulerItem::TIMEOUT,
+                                      /* is_static_string= */ true, "delay", this->delay_.value(x...), std::move(f),
+                                      /* is_retry= */ false, /* skip_cancel= */ this->num_running_ > 1);
+    }
   }
   float get_setup_priority() const override { return setup_priority::HARDWARE; }