From 6d0c61dc738c46b8ccaedd47d309bd4da606b2e2 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 7 Apr 2026 14:17:41 -1000
Subject: [PATCH] [core] Use TemplatableStorage alias to select TemplatableFn
 or TemplatableValue

TEMPLATABLE_VALUE macro now uses TemplatableStorage<T, Ts...> which
selects TemplatableFn for non-string types (4 bytes) and
TemplatableValue for std::string (full PROGMEM/FlashStringHelper support).

Fixes ESP8266 compile failure where __FlashStringHelper* couldn't
assign to TemplatableFn<std::string>.
---
 esphome/core/automation.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/esphome/core/automation.h b/esphome/core/automation.h
index 3b04373fc6..d286782293 100644
--- a/esphome/core/automation.h
+++ b/esphome/core/automation.h
@@ -62,9 +62,18 @@ template<typename T, typename... X> class TemplatableFn {
   T (*f_)(X...){nullptr};
 };
 
+// Forward declaration for TemplatableValue (string specialization needs it)
+template<typename T, typename... X> class TemplatableValue;
+
+/// Selects TemplatableFn (4 bytes) for non-string types, TemplatableValue (8 bytes) for std::string.
+/// std::string needs TemplatableValue for const char*, __FlashStringHelper*, and PROGMEM support.
+template<typename T, typename... X>
+using TemplatableStorage =
+    std::conditional_t<std::same_as<T, std::string>, TemplatableValue<T, X...>, TemplatableFn<T, X...>>;
+
 #define TEMPLATABLE_VALUE_(type, name) \
  protected: \
-  TemplatableFn<type, Ts...> name##_{}; \
+  TemplatableStorage<type, Ts...> name##_{}; \
 \
  public: \
   template<typename V> void set_##name(V name) { this->name##_ = name; }