Use ifdef to split pre_setup signatures for const correctness

When MAC suffix is not used, pre_setup takes const char* parameters
so string literals stay in flash. When MAC suffix is used, it takes
mutable char* for the static buffers that get overwritten with the
actual MAC address. This avoids const_cast entirely.

Also adds ESPHOME_NAME_ADD_MAC_SUFFIX define for static analysis.

esphome/core/application.h

@@ -138,26 +138,35 @@ static constexpr uint32_t TEARDOWN_TIMEOUT_REBOOT_MS = 1000;  // 1 second for qu
 
 class Application {
  public:
-  void pre_setup(char *name, size_t name_len, char *friendly_name, size_t friendly_name_len, bool name_add_mac_suffix) {
+#ifdef ESPHOME_NAME_ADD_MAC_SUFFIX
+  /// Pre-setup with MAC suffix: overwrites placeholder in mutable static buffers with actual MAC.
+  void pre_setup(char *name, size_t name_len, char *friendly_name, size_t friendly_name_len) {
     arch_init();
-    this->name_add_mac_suffix_ = name_add_mac_suffix;
-    if (name_add_mac_suffix) {
-      // MAC address length: 12 hex chars + null terminator
-      constexpr size_t mac_address_len = 13;
-      // MAC address suffix length (last 6 characters of 12-char MAC address string)
-      constexpr size_t mac_address_suffix_len = 6;
-      char mac_addr[mac_address_len];
-      get_mac_address_into_buffer(mac_addr);
-      // Overwrite the placeholder suffix in the static buffers with actual MAC
-      memcpy(name + name_len - mac_address_suffix_len, mac_addr + mac_address_suffix_len, mac_address_suffix_len);
-      if (friendly_name_len > 0) {
-        memcpy(friendly_name + friendly_name_len - mac_address_suffix_len, mac_addr + mac_address_suffix_len,
-               mac_address_suffix_len);
-      }
+    this->name_add_mac_suffix_ = true;
+    // MAC address length: 12 hex chars + null terminator
+    constexpr size_t mac_address_len = 13;
+    // MAC address suffix length (last 6 characters of 12-char MAC address string)
+    constexpr size_t mac_address_suffix_len = 6;
+    char mac_addr[mac_address_len];
+    get_mac_address_into_buffer(mac_addr);
+    // Overwrite the placeholder suffix in the mutable static buffers with actual MAC
+    memcpy(name + name_len - mac_address_suffix_len, mac_addr + mac_address_suffix_len, mac_address_suffix_len);
+    if (friendly_name_len > 0) {
+      memcpy(friendly_name + friendly_name_len - mac_address_suffix_len, mac_addr + mac_address_suffix_len,
+             mac_address_suffix_len);
     }
     this->name_ = StringRef(name, name_len);
     this->friendly_name_ = StringRef(friendly_name, friendly_name_len);
   }
+#else
+  /// Pre-setup without MAC suffix: StringRef points directly at const string literals in flash.
+  void pre_setup(const char *name, size_t name_len, const char *friendly_name, size_t friendly_name_len) {
+    arch_init();
+    this->name_add_mac_suffix_ = false;
+    this->name_ = StringRef(name, name_len);
+    this->friendly_name_ = StringRef(friendly_name, friendly_name_len);
+  }
+#endif
 
 #ifdef USE_DEVICES
   void register_device(Device *device) { this->devices_.push_back(device); }

esphome/core/config.py

@@ -568,11 +568,11 @@ async def to_code(config: ConfigType) -> None:
         """Create a name expression for pre_setup.
 
         With MAC suffix: emits a static mutable buffer with placeholder suffix.
-        Without: casts the string literal to char*.
+        Without: passes the string literal directly as const char*.
         Returns (expression, length).
         """
         if not value:
-            return cg.RawExpression('(char *) ""'), 0
+            return cg.RawExpression('""'), 0
         if name_add_mac_suffix:
             value_with_placeholder = f"{value}{sep}XXXXXX"
             cg.add_global(
@@ -581,10 +581,7 @@ async def to_code(config: ConfigType) -> None:
                 )
             )
             return cg.RawExpression(var_name), len(value_with_placeholder)
-        return (
-            cg.RawExpression(f"(char *) {cpp_string_escape(value)}"),
-            len(value),
-        )
+        return cg.RawExpression(cpp_string_escape(value)), len(value)
 
     name_expr, name_len = _make_app_name_expr(
         name, _APP_NAME_BUF_VAR, _APP_NAME_MAC_SEP
@@ -592,11 +589,9 @@ async def to_code(config: ConfigType) -> None:
     friendly_expr, friendly_len = _make_app_name_expr(
         friendly_name, _APP_FRIENDLY_NAME_BUF_VAR, _APP_FRIENDLY_NAME_MAC_SEP
     )
-    cg.add(
-        cg.App.pre_setup(
-            name_expr, name_len, friendly_expr, friendly_len, name_add_mac_suffix
-        )
-    )
+    if name_add_mac_suffix:
+        cg.add_define("ESPHOME_NAME_ADD_MAC_SUFFIX")
+    cg.add(cg.App.pre_setup(name_expr, name_len, friendly_expr, friendly_len))
     # Define component count for static allocation
     cg.add_define("ESPHOME_COMPONENT_COUNT", len(CORE.component_ids))
 

esphome/core/defines.h

@@ -13,6 +13,7 @@
 #define ESPHOME_PROJECT_VERSION "v2"
 #define ESPHOME_PROJECT_VERSION_30 "v2"
 #define ESPHOME_VARIANT "ESP32"
+#define ESPHOME_NAME_ADD_MAC_SUFFIX
 #define ESPHOME_DEBUG_SCHEDULER
 #define ESPHOME_DEBUG_API