relay: minimal build warnings

code/espurna/relay.cpp

@@ -253,6 +253,14 @@ constexpr RelayProvider provider(size_t index) {
     );
 }
 
+#if MQTT_SUPPORT || API_SUPPORT
+PROGMEM_STRING(PayloadOn, RELAY_MQTT_ON);
+PROGMEM_STRING(PayloadOff, RELAY_MQTT_OFF);
+PROGMEM_STRING(PayloadToggle, RELAY_MQTT_TOGGLE);
+#endif
+
+#if MQTT_SUPPORT
+
 constexpr RelayMqttTopicMode mqttTopicMode(size_t index) {
     return (
         (index == 0) ? (RELAY1_MQTT_TOPIC_MODE) :
@@ -266,10 +274,6 @@ constexpr RelayMqttTopicMode mqttTopicMode(size_t index) {
     );
 }
 
-PROGMEM_STRING(PayloadOn, RELAY_MQTT_ON);
-PROGMEM_STRING(PayloadOff, RELAY_MQTT_OFF);
-PROGMEM_STRING(PayloadToggle, RELAY_MQTT_TOGGLE);
-
 #define RELAY_SETTING_STRING_RESULT(FIRST, SECOND, THIRD, FOURTH, FIFTH, SIXTH, SEVENTH, EIGHTH)\
     (index == 0) ? STRING_VIEW_SETTING(FIRST) :\
     (index == 1) ? STRING_VIEW_SETTING(SECOND) :\
@@ -321,6 +325,8 @@ constexpr PayloadStatus mqttDisconnectionStatus(size_t index) {
     );
 }
 
+#endif
+
 } // namespace
 } // namespace build
 
@@ -968,20 +974,19 @@ RelaySync syncMode() {
     return getSetting(keys::Sync, build::syncMode());
 }
 
-[[gnu::unused]]
+#if MQTT_SUPPORT || API_SUPPORT
 String payloadOn() {
     return getSetting(keys::PayloadOn, StringView(build::PayloadOn));
 }
 
-[[gnu::unused]]
 String payloadOff() {
     return getSetting(keys::PayloadOff, StringView(build::PayloadOff));
 }
 
-[[gnu::unused]]
 String payloadToggle() {
     return getSetting(keys::PayloadToggle, StringView(build::PayloadToggle));
 }
+#endif
 
 #if MQTT_SUPPORT
 String mqttTopicSub(size_t index) {