🚨 Fix some compiler warnings

Marlin/src/module/temperature.cpp

@@ -751,7 +751,7 @@ volatile bool Temperature::raw_temps_ready = false;
       // Report heater states every 2 seconds
       if (ELAPSED(ms, next_temp_ms)) {
         #if HAS_TEMP_SENSOR
-          print_heater_states(ischamber ? active_extruder : (isbed ? active_extruder : heater_id));
+          print_heater_states(heater_id < 0 ? active_extruder : (int8_t)heater_id);
           SERIAL_EOL();
         #endif
         next_temp_ms = ms + 2000UL;
@@ -2817,6 +2817,9 @@ void Temperature::init() {
 
 #if HAS_THERMAL_PROTECTION
 
+  #pragma GCC diagnostic push
+  #pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+
   Temperature::tr_state_machine_t Temperature::tr_state_machine[NR_HEATER_RUNAWAY]; // = { { TRInactive, 0 } };
 
   /**
@@ -2946,6 +2949,8 @@ void Temperature::init() {
     }
   }
 
+  #pragma GCC diagnostic pop
+
 #endif // HAS_THERMAL_PROTECTION
 
 void Temperature::disable_all_heaters() {
@@ -3669,6 +3674,9 @@ void Temperature::isr() {
 
   switch (adc_sensor_state) {
 
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+
     case SensorsReady: {
       // All sensors have been read. Stay in this state for a few
       // ISRs to save on calls to temp update/checking code below.
@@ -3686,6 +3694,8 @@ void Temperature::isr() {
       }
     }
 
+    #pragma GCC diagnostic pop
+
     case StartSampling:                                   // Start of sampling loops. Do updates/checks.
       if (++temp_count >= OVERSAMPLENR) {                 // 10 * 16 * 1/(16000000/64/256)  = 164ms.
         temp_count = 0;
@@ -3917,7 +3927,7 @@ void Temperature::isr() {
     delay(2);
   }
 
-  void Temperature::print_heater_states(const uint8_t target_extruder
+  void Temperature::print_heater_states(const int8_t target_extruder
     OPTARG(HAS_TEMP_REDUNDANT, const bool include_r/*=false*/)
   ) {
     #if HAS_TEMP_HOTEND