From a20b0a96b90f21f32b4a9325abc1ea6ed41312e6 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Fri, 27 Mar 2026 16:14:55 -1000
Subject: [PATCH] Use init_array_from helper for optimal codegen

Uses memcpy for trivially copyable types, element-wise copy otherwise.
ESPHOME_DEBUG_ASSERT catches size mismatches in integration tests.
---
 esphome/components/binary_sensor/automation.h |  6 +-----
 esphome/core/helpers.h                        | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/esphome/components/binary_sensor/automation.h b/esphome/components/binary_sensor/automation.h
index aa3d5d7fa4..1875910aff 100644
--- a/esphome/components/binary_sensor/automation.h
+++ b/esphome/components/binary_sensor/automation.h
@@ -131,11 +131,7 @@ template<size_t N> class MultiClickTrigger : public MultiClickTriggerBase {
  public:
   MultiClickTrigger(BinarySensor *parent, std::initializer_list<MultiClickTriggerEvent> timing)
       : MultiClickTriggerBase(parent) {
-    ESPHOME_DEBUG_ASSERT(timing.size() == N);
-    size_t i = 0;
-    for (const auto &t : timing) {
-      this->timing_storage_[i++] = t;
-    }
+    init_array_from(this->timing_storage_, timing);
     this->timing_ = this->timing_storage_.data();
     this->timing_count_ = N;
   }
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 82c6b3833c..51feaa57c5 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -497,6 +497,21 @@ template<typename T, size_t MAX_CAPACITY = std::numeric_limits<uint16_t>::max()>
   index_type capacity_{0};
 };
 
+/// Initialize a std::array from an initializer_list. Uses memcpy for trivially copyable types (optimal codegen),
+/// falls back to element-wise copy for non-trivially copyable types (e.g. TemplatableValue).
+/// N is set by code generation; ESPHOME_DEBUG_ASSERT catches mismatches in debug/integration tests.
+template<typename T, size_t N> inline void init_array_from(std::array<T, N> &dest, std::initializer_list<T> src) {
+  ESPHOME_DEBUG_ASSERT(src.size() == N);
+  if constexpr (std::is_trivially_copyable_v<T>) {
+    __builtin_memcpy(dest.data(), src.begin(), N * sizeof(T));
+  } else {
+    size_t i = 0;
+    for (const auto &v : src) {
+      dest[i++] = v;
+    }
+  }
+}
+
 /// Fixed-capacity vector - allocates once at runtime, never reallocates
 /// This avoids std::vector template overhead (_M_realloc_insert, _M_default_append)
 /// when size is known at initialization but not at compile time