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/text_sensor/filter.h

@@ -131,11 +131,7 @@ bool substitute_filter_apply(const Substitution *substitutions, size_t count, st
 template<size_t N> class SubstituteFilter : public Filter {
  public:
   explicit SubstituteFilter(const std::initializer_list<Substitution> &substitutions) {
-    ESPHOME_DEBUG_ASSERT(substitutions.size() == N);
-    size_t i = 0;
-    for (const auto &s : substitutions) {
-      this->substitutions_[i++] = s;
-    }
+    init_array_from(this->substitutions_, substitutions);
   }
   bool new_value(std::string &value) override { return substitute_filter_apply(this->substitutions_.data(), N, value); }
 

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