Add multi-extruder condition

Marlin/Configuration_adv.h

  * Universal tool change settings.
  * Applies to all types of extruders except where explicitly noted.
  */
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   // Z raise distance for tool-change, as needed for some extruders
   #define TOOLCHANGE_ZRAISE                 2 // (mm)
   //#define TOOLCHANGE_ZRAISE_BEFORE_RETRACT  // Apply raise before swap retraction (if enabled)
     //#define TOOLCHANGE_PARK_X_ONLY          // X axis only move
     //#define TOOLCHANGE_PARK_Y_ONLY          // Y axis only move
   #endif
-#endif // EXTRUDERS > 1
+#endif // HAS_MULTI_EXTRUDER
 
 /**
  * Advanced Pause

Marlin/src/HAL/DUE/HAL_SPI.cpp

       SPI_Enable(SPI0);
 
       SET_OUTPUT(DAC0_SYNC);
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         SET_OUTPUT(DAC1_SYNC);
         WRITE(DAC1_SYNC, HIGH);
       #endif

Marlin/src/HAL/LPC1768/inc/SanityCheck.h

     #error "Serial port pins (2) conflict with probe pin!"
   #elif IS_TX2(X_ENABLE_PIN) || IS_RX2(X_DIR_PIN) || IS_TX2(Y_ENABLE_PIN) || IS_RX2(Y_DIR_PIN)
     #error "Serial port pins (2) conflict with X/Y stepper pins!"
-  #elif EXTRUDERS > 1 && (IS_TX2(E1_ENABLE_PIN) || (AXIS_HAS_SPI(E1) && IS_TX2(E1_CS_PIN)))
+  #elif HAS_MULTI_EXTRUDER && (IS_TX2(E1_ENABLE_PIN) || (AXIS_HAS_SPI(E1) && IS_TX2(E1_CS_PIN)))
     #error "Serial port pins (2) conflict with E1 stepper pins!"
   #elif EXTRUDERS && (IS_RX2(E0_DIR_PIN) || IS_RX2(E0_STEP_PIN))
     #error "Serial port pins (2) conflict with E stepper pins!"
     #error "Serial port pins (3) conflict with Z3 pins!"
   #elif PIN_IS_TX3(Z4_DIR) || PIN_IS_RX3(Z4_STEP)
     #error "Serial port pins (3) conflict with Z4 pins!"
-  #elif EXTRUDERS > 1 && (PIN_IS_TX3(E1_DIR) || PIN_IS_RX3(E1_STEP))
+  #elif HAS_MULTI_EXTRUDER && (PIN_IS_TX3(E1_DIR) || PIN_IS_RX3(E1_STEP))
     #error "Serial port pins (3) conflict with E1 pins!"
   #endif
   #undef PIN_IS_TX3
       #error "One or more i2c (1) pins overlaps with Z3 pins! Disable i2c peripherals."
     #elif PIN_IS_SDA1(Z4_DIR) || PIN_IS_SCL1(Z4_STEP)
       #error "One or more i2c (1) pins overlaps with Z4 pins! Disable i2c peripherals."
-    #elif EXTRUDERS > 1 && (PIN_IS_SDA1(E1_DIR) || PIN_IS_SCL1(E1_STEP))
+    #elif HAS_MULTI_EXTRUDER && (PIN_IS_SDA1(E1_DIR) || PIN_IS_SCL1(E1_STEP))
       #error "One or more i2c (1) pins overlaps with E1 pins! Disable i2c peripherals."
     #endif
     #undef PIN_IS_SDA1
       #error "i2c SDA2 overlaps with Z3 enable pin! Disable i2c peripherals."
     #elif PIN_IS_SDA2(Z4_ENABLE)
       #error "i2c SDA2 overlaps with Z4 enable pin! Disable i2c peripherals."
-    #elif EXTRUDERS > 1 && PIN_IS_SDA2(E1_ENABLE)
+    #elif HAS_MULTI_EXTRUDER && PIN_IS_SDA2(E1_ENABLE)
       #error "i2c SDA2 overlaps with E1 enable pin! Disable i2c peripherals."
-    #elif EXTRUDERS > 1 && AXIS_HAS_SPI(E1) && PIN_IS_SDA2(E1_CS)
+    #elif HAS_MULTI_EXTRUDER && AXIS_HAS_SPI(E1) && PIN_IS_SDA2(E1_CS)
       #error "i2c SDA2 overlaps with E1 CS pin! Disable i2c peripherals."
     #elif EXTRUDERS && (PIN_IS_SDA2(E0_STEP) || PIN_IS_SDA2(E0_DIR))
       #error "i2c SCL2 overlaps with E0 STEP/DIR pin! Disable i2c peripherals."

Marlin/src/feature/dac/dac_dac084s085.cpp

 
   // All SPI chip-select HIGH
   SET_OUTPUT(DAC0_SYNC);
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     SET_OUTPUT(DAC1_SYNC);
   #endif
   cshigh();
   spiSend(SPI_CHAN_DAC, externalDac_buf, COUNT(externalDac_buf));
   WRITE(DAC0_SYNC, HIGH);
 
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     //init Piggy DAC
     DELAY_US(2);
     WRITE(DAC1_SYNC, LOW);
 
 void dac084s085::cshigh() {
   WRITE(DAC0_SYNC, HIGH);
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     WRITE(DAC1_SYNC, HIGH);
   #endif
   WRITE(SPI_EEPROM1_CS, HIGH);

Marlin/src/feature/fwretract.cpp

 
 // private:
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   bool FWRetract::retracted_swap[EXTRUDERS];          // Which extruders are swap-retracted
 #endif
 
 
   LOOP_L_N(i, EXTRUDERS) {
     retracted[i] = false;
-    #if EXTRUDERS > 1
-      retracted_swap[i] = false;
-    #endif
+    TERN_(HAS_MULTI_EXTRUDER, retracted_swap[i] = false);
     current_retract[i] = 0.0;
   }
 }
  *       included in the G-code. Use M207 Z0 to to prevent double hop.
  */
 void FWRetract::retract(const bool retracting
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     , bool swapping/*=false*/
   #endif
 ) {
   if (retracted[active_extruder] == retracting) return;
 
   // Prevent two swap-retract or recovers in a row
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     // Allow G10 S1 only after G11
     if (swapping && retracted_swap[active_extruder] == retracting) return;
     // G11 priority to recover the long retract if activated
     );
     LOOP_L_N(i, EXTRUDERS) {
       SERIAL_ECHOLNPAIR("retracted[", i, "] ", retracted[i]);
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         SERIAL_ECHOLNPAIR("retracted_swap[", i, "] ", retracted_swap[i]);
       #endif
     }
   retracted[active_extruder] = retracting;                // Active extruder now retracted / recovered
 
   // If swap retract/recover update the retracted_swap flag too
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     if (swapping) retracted_swap[active_extruder] = retracting;
   #endif
 
     SERIAL_ECHOLNPAIR("active_extruder ", active_extruder);
     LOOP_L_N(i, EXTRUDERS) {
       SERIAL_ECHOLNPAIR("retracted[", i, "] ", retracted[i]);
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         SERIAL_ECHOLNPAIR("retracted_swap[", i, "] ", retracted_swap[i]);
       #endif
     }

Marlin/src/feature/fwretract.h

 
 class FWRetract {
 private:
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     static bool retracted_swap[EXTRUDERS];         // Which extruders are swap-retracted
   #endif
 
   }
 
   static void retract(const bool retracting
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       , bool swapping = false
     #endif
   );

Marlin/src/feature/powerloss.cpp

     TERN_(HAS_POSITION_SHIFT, info.position_shift = position_shift);
     info.feedrate = uint16_t(feedrate_mm_s * 60.0f);
 
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       info.active_extruder = active_extruder;
     #endif
 
     #if DISABLED(NO_VOLUMETRICS)
       info.volumetric_enabled = parser.volumetric_enabled;
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         for (int8_t e = 0; e < EXTRUDERS; e++) info.filament_size[e] = planner.filament_size[e];
       #else
         if (parser.volumetric_enabled) info.filament_size[0] = planner.filament_size[active_extruder];
 
   // Recover volumetric extrusion state
   #if DISABLED(NO_VOLUMETRICS)
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       for (int8_t e = 0; e < EXTRUDERS; e++) {
         sprintf_P(cmd, PSTR("M200 T%i D%s"), e, dtostrf(info.filament_size[e], 1, 3, str_1));
         gcode.process_subcommands_now(cmd);
   #endif
 
   // Select the previously active tool (with no_move)
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     sprintf_P(cmd, PSTR("T%i S"), info.active_extruder);
     gcode.process_subcommands_now(cmd);
   #endif
 
         DEBUG_ECHOLNPAIR("feedrate: ", info.feedrate);
 
-        #if EXTRUDERS > 1
+        #if HAS_MULTI_EXTRUDER
           DEBUG_ECHOLNPAIR("active_extruder: ", int(info.active_extruder));
         #endif
 

Marlin/src/feature/powerloss.h

 
   uint16_t feedrate;
 
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     uint8_t active_extruder;
   #endif
 

Marlin/src/gcode/config/M217.cpp

 
 #include "../../inc/MarlinConfigPre.h"
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
 
 #include "../gcode.h"
 #include "../../module/tool_change.h"
   M217_report();
 }
 
-#endif // EXTRUDERS > 1
+#endif // HAS_MULTI_EXTRUDER

Marlin/src/gcode/control/T.cpp

 #include "../gcode.h"
 #include "../../module/tool_change.h"
 
-#if ENABLED(DEBUG_LEVELING_FEATURE) || EXTRUDERS > 1
+#if EITHER(HAS_MULTI_EXTRUDER, DEBUG_LEVELING_FEATURE)
   #include "../../module/motion.h"
 #endif
 

Marlin/src/gcode/feature/fwretract/G10_G11.cpp

  *       TODO: Handle 'G10 P' for tool settings and 'G10 L' for workspace settings
  */
 void GcodeSuite::G10() {
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     const bool rs = parser.boolval('S');
   #endif
   fwretract.retract(true
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       , rs
     #endif
   );

Marlin/src/gcode/feature/pause/M600.cpp

 #include "../../../module/motion.h"
 #include "../../../module/printcounter.h"
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   #include "../../../module/tool_change.h"
 #endif
 
     if (!all_axes_known()) home_all_axes();
   #endif
 
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     // Change toolhead if specified
     const uint8_t active_extruder_before_filament_change = active_extruder;
     if (active_extruder != target_extruder && TERN1(DUAL_X_CARRIAGE, !dxc_is_duplicating()))
     #endif
   }
 
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     // Restore toolhead if it was changed
     if (active_extruder_before_filament_change != active_extruder)
       tool_change(active_extruder_before_filament_change, false);

Marlin/src/gcode/feature/pause/M603.cpp

 #include "../../../module/motion.h"
 #include "../../../module/printcounter.h"
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   #include "../../../module/tool_change.h"
 #endif
 

Marlin/src/gcode/feature/pause/M701_M702.cpp

 #include "../../../module/temperature.h"
 #include "../../../feature/pause.h"
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   #include "../../../module/tool_change.h"
 #endif
 
   // Show initial "wait for load" message
   TERN_(HAS_LCD_MENU, lcd_pause_show_message(PAUSE_MESSAGE_LOAD, PAUSE_MODE_LOAD_FILAMENT, target_extruder));
 
-  #if EXTRUDERS > 1 && DISABLED(PRUSA_MMU2)
+  #if HAS_MULTI_EXTRUDER && DISABLED(PRUSA_MMU2)
     // Change toolhead if specified
     uint8_t active_extruder_before_filament_change = active_extruder;
     if (active_extruder != target_extruder)
   if (park_point.z > 0)
     do_blocking_move_to_z(_MAX(current_position.z - park_point.z, 0), feedRate_t(NOZZLE_PARK_Z_FEEDRATE));
 
-  #if EXTRUDERS > 1 && DISABLED(PRUSA_MMU2)
+  #if HAS_MULTI_EXTRUDER && DISABLED(PRUSA_MMU2)
     // Restore toolhead if it was changed
     if (active_extruder_before_filament_change != active_extruder)
       tool_change(active_extruder_before_filament_change, false);
   // Show initial "wait for unload" message
   TERN_(HAS_LCD_MENU, lcd_pause_show_message(PAUSE_MESSAGE_UNLOAD, PAUSE_MODE_UNLOAD_FILAMENT, target_extruder));
 
-  #if EXTRUDERS > 1 && DISABLED(PRUSA_MMU2)
+  #if HAS_MULTI_EXTRUDER && DISABLED(PRUSA_MMU2)
     // Change toolhead if specified
     uint8_t active_extruder_before_filament_change = active_extruder;
     if (active_extruder != target_extruder)
   #if ENABLED(PRUSA_MMU2)
     mmu2.unload();
   #else
-    #if EXTRUDERS > 1 && ENABLED(FILAMENT_UNLOAD_ALL_EXTRUDERS)
+    #if BOTH(HAS_MULTI_EXTRUDER, FILAMENT_UNLOAD_ALL_EXTRUDERS)
       if (!parser.seenval('T')) {
         HOTEND_LOOP() {
           if (e != active_extruder) tool_change(e, false);
   if (park_point.z > 0)
     do_blocking_move_to_z(_MAX(current_position.z - park_point.z, 0), feedRate_t(NOZZLE_PARK_Z_FEEDRATE));
 
-  #if EXTRUDERS > 1 && DISABLED(PRUSA_MMU2)
+  #if HAS_MULTI_EXTRUDER && DISABLED(PRUSA_MMU2)
     // Restore toolhead if it was changed
     if (active_extruder_before_filament_change != active_extruder)
       tool_change(active_extruder_before_filament_change, false);

Marlin/src/gcode/gcode.cpp

         case 211: M211(); break;                                  // M211: Enable, Disable, and/or Report software endstops
       #endif
 
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         case 217: M217(); break;                                  // M217: Set filament swap parameters
       #endif
 

Marlin/src/gcode/gcode.h

 
   static void M211();
 
-  #if EXTRUDERS > 1
-    static void M217();
-  #endif
+  TERN_(HAS_MULTI_EXTRUDER, static void M217());
 
   TERN_(HAS_HOTEND_OFFSET, static void M218());
 

Marlin/src/inc/Conditionals_LCD.h

   #undef MK2_MULTIPLEXER
   #undef PRUSA_MMU2
   #undef HOTEND_IDLE_TIMEOUT
+#elif EXTRUDERS > 1
+  #define HAS_MULTI_EXTRUDER 1
 #endif
 
 #if ENABLED(SWITCHING_EXTRUDER)   // One stepper for every two EXTRUDERS

Marlin/src/inc/Conditionals_post.h

   #define FILAMENT_CHANGE_SLOW_LOAD_LENGTH 0
 #endif
 
-#if EXTRUDERS > 1 && !defined(TOOLCHANGE_FS_EXTRA_PRIME)
+#if HAS_MULTI_EXTRUDER && !defined(TOOLCHANGE_FS_EXTRA_PRIME)
   #define TOOLCHANGE_FS_EXTRA_PRIME 0
 #endif
 

Marlin/src/inc/SanityCheck.h

 /**
  * Options only for EXTRUDERS > 1
  */
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
 
   #if EXTRUDERS > 8
     #error "Marlin supports a maximum of 8 EXTRUDERS."
  * Mixing Extruder requirements
  */
 #if ENABLED(MIXING_EXTRUDER)
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     #error "For MIXING_EXTRUDER set MIXING_STEPPERS > 1 instead of EXTRUDERS > 1."
   #elif MIXING_STEPPERS < 2
     #error "You must set MIXING_STEPPERS >= 2 for a mixing extruder."

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/endstop_state_screen.cpp

   #else
     PIN_DISABLED(1, 4, GET_TEXT_F(MSG_RUNOUT_1), FIL_RUNOUT)
   #endif
-  #if ENABLED(FILAMENT_RUNOUT_SENSOR) && PIN_EXISTS(FIL_RUNOUT2) && EXTRUDERS > 1
+  #if BOTH(HAS_MULTI_EXTRUDER, FILAMENT_RUNOUT_SENSOR) && PIN_EXISTS(FIL_RUNOUT2)
     PIN_ENABLED (3, 4, GET_TEXT_F(MSG_RUNOUT_2), FIL_RUNOUT2, FIL_RUNOUT_STATE)
   #else
     PIN_DISABLED(3, 4, GET_TEXT_F(MSG_RUNOUT_2), FIL_RUNOUT2)

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/linear_advance_screen.cpp

   widgets_t w(what);
   w.precision(2, DEFAULT_LOWEST).color(e_axis);
   w.heading(           GET_TEXT_F(MSG_LINEAR_ADVANCE));
-  #if EXTRUDERS == 1
+  #if !HAS_MULTI_EXTRUDER
     w.adjuster(     2, GET_TEXT_F(MSG_LINEAR_ADVANCE_K),    getLinearAdvance_mm_mm_s(E0) );
   #else
     w.adjuster(     2, GET_TEXT_F(MSG_LINEAR_ADVANCE_K1), getLinearAdvance_mm_mm_s(E0) );
   switch (tag) {
     case  2: UI_DECREMENT(LinearAdvance_mm_mm_s, E0); break;
     case  3: UI_INCREMENT(LinearAdvance_mm_mm_s, E0); break;
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       case  4: UI_DECREMENT(LinearAdvance_mm_mm_s, E1);  break;
       case  5: UI_INCREMENT(LinearAdvance_mm_mm_s, E1); break;
       #if EXTRUDERS > 2

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/max_velocity_screen.cpp

   w.color(z_axis)    .adjuster(  6, GET_TEXT_F(MSG_VMAX_Z), getAxisMaxFeedrate_mm_s(Z) );
   #if EXTRUDERS == 1 || DISABLED(DISTINCT_E_FACTORS)
     w.color(e_axis)  .adjuster(  8, GET_TEXT_F(MSG_VMAX_E), getAxisMaxFeedrate_mm_s(E0) );
-  #elif EXTRUDERS > 1
+  #elif HAS_MULTI_EXTRUDER
     w.heading(GET_TEXT_F(MSG_VMAX_E));
     w.color(e_axis)  .adjuster(  8, F(LCD_STR_E0), getAxisMaxFeedrate_mm_s(E0) );
     w.color(e_axis)  .adjuster( 10, F(LCD_STR_E1), getAxisMaxFeedrate_mm_s(E1) );

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/move_axis_screen.cpp

   w.color(Theme::e_axis);
   #if EXTRUDERS == 1
     w.adjuster(  8, GET_TEXT_F(MSG_AXIS_E),  screen_data.MoveAxisScreen.e_rel[0], canMove(E0));
-  #elif EXTRUDERS > 1
+  #elif HAS_MULTI_EXTRUDER
     w.adjuster(  8, GET_TEXT_F(MSG_AXIS_E1), screen_data.MoveAxisScreen.e_rel[0], canMove(E0));
     w.adjuster( 10, GET_TEXT_F(MSG_AXIS_E2), screen_data.MoveAxisScreen.e_rel[1], canMove(E1));
     #if EXTRUDERS > 2
     // For extruders, also update relative distances.
     case  8: UI_DECREMENT_AXIS(E0); screen_data.MoveAxisScreen.e_rel[0] -= increment; break;
     case  9: UI_INCREMENT_AXIS(E0); screen_data.MoveAxisScreen.e_rel[0] += increment; break;
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
     case 10: UI_DECREMENT_AXIS(E1); screen_data.MoveAxisScreen.e_rel[1] -= increment; break;
     case 11: UI_INCREMENT_AXIS(E1); screen_data.MoveAxisScreen.e_rel[1] += increment; break;
     #endif

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/nudge_nozzle_screen.cpp

 
 void NudgeNozzleScreen::onEntry() {
   screen_data.NudgeNozzleScreen.show_offsets = false;
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     screen_data.NudgeNozzleScreen.link_nozzles = true;
   #endif
   screen_data.NudgeNozzleScreen.rel.reset();
   #endif
   w.color(z_axis).adjuster(6, GET_TEXT_F(MSG_AXIS_Z), screen_data.NudgeNozzleScreen.rel.z / getAxisSteps_per_mm(Z));
   w.increments();
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     w.toggle(8, GET_TEXT_F(MSG_ADJUST_BOTH_NOZZLES), screen_data.NudgeNozzleScreen.link_nozzles);
   #endif
 
-  #if EXTRUDERS > 1 || HAS_BED_PROBE
+  #if HAS_MULTI_EXTRUDER || HAS_BED_PROBE
     w.toggle(9, GET_TEXT_F(MSG_SHOW_OFFSETS), screen_data.NudgeNozzleScreen.show_offsets);
 
     if (screen_data.NudgeNozzleScreen.show_offsets) {
 
 bool NudgeNozzleScreen::onTouchHeld(uint8_t tag) {
   const float inc = getIncrement();
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     const bool link = screen_data.NudgeNozzleScreen.link_nozzles;
   #else
     constexpr bool link = true;
     case 5: steps = mmToWholeSteps(inc, Y); smartAdjustAxis_steps( steps, Y, link); screen_data.NudgeNozzleScreen.rel.y += steps; break;
     case 6: steps = mmToWholeSteps(inc, Z); smartAdjustAxis_steps(-steps, Z, link); screen_data.NudgeNozzleScreen.rel.z -= steps; break;
     case 7: steps = mmToWholeSteps(inc, Z); smartAdjustAxis_steps( steps, Z, link); screen_data.NudgeNozzleScreen.rel.z += steps; break;
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       case 8: screen_data.NudgeNozzleScreen.link_nozzles = !link; break;
     #endif
     case 9: screen_data.NudgeNozzleScreen.show_offsets = !screen_data.NudgeNozzleScreen.show_offsets; break;
     default: return false;
   }
-  #if EXTRUDERS > 1 || HAS_BED_PROBE
+  #if HAS_MULTI_EXTRUDER || HAS_BED_PROBE
     SaveSettingsDialogBox::settingsChanged();
   #endif
   return true;

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/screen_data.h

     struct {
       struct base_numeric_adjustment_t placeholder;
       xyz_int_t rel;
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         bool link_nozzles;
       #endif
       bool show_offsets;

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/stepper_current_screen.cpp

   w.color(z_axis)  .adjuster( 6, GET_TEXT_F(MSG_AXIS_Z),  getAxisCurrent_mA(Z) );
   #if EXTRUDERS == 1
     w.color(e_axis).adjuster( 8, GET_TEXT_F(MSG_AXIS_E),  getAxisCurrent_mA(E0) );
-  #elif EXTRUDERS > 1
+  #elif HAS_MULTI_EXTRUDER
     w.color(e_axis).adjuster( 8, GET_TEXT_F(MSG_AXIS_E1), getAxisCurrent_mA(E0) );
     w.color(e_axis).adjuster(10, GET_TEXT_F(MSG_AXIS_E2), getAxisCurrent_mA(E1) );
     #if EXTRUDERS > 2
     case  7: UI_INCREMENT(AxisCurrent_mA, Z ); break;
     case  8: UI_DECREMENT(AxisCurrent_mA, E0); break;
     case  9: UI_INCREMENT(AxisCurrent_mA, E0); break;
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
     case 10: UI_DECREMENT(AxisCurrent_mA, E1); break;
     case 11: UI_INCREMENT(AxisCurrent_mA, E1); break;
     #endif

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/steps_screen.cpp

   w.color(z_axis)     .adjuster( 6, GET_TEXT_F(MSG_AXIS_Z),  getAxisSteps_per_mm(Z) );
   #if EXTRUDERS == 1 || DISABLED(DISTINCT_E_FACTORS)
     w.color(e_axis)   .adjuster( 8, GET_TEXT_F(MSG_AXIS_E),  getAxisSteps_per_mm(E0) );
-  #elif EXTRUDERS > 1
+  #elif HAS_MULTI_EXTRUDER
     w.color(e_axis)   .adjuster( 8, GET_TEXT_F(MSG_AXIS_E1), getAxisSteps_per_mm(E0) );
     w.color(e_axis)   .adjuster(10, GET_TEXT_F(MSG_AXIS_E2), getAxisSteps_per_mm(E1) );
     #if EXTRUDERS > 2
     case  7: UI_INCREMENT(AxisSteps_per_mm, Z);  break;
     case  8: UI_DECREMENT(AxisSteps_per_mm, E0); break;
     case  9: UI_INCREMENT(AxisSteps_per_mm, E0); break;
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
     case 10: UI_DECREMENT(AxisSteps_per_mm, E1); break;
     case 11: UI_INCREMENT(AxisSteps_per_mm, E1); break;
     #endif

Marlin/src/lcd/extui/lib/ftdi_eve_touch_ui/screens/stress_test_screen.cpp

       injectCommands_P(PSTR(
         "G0 X100 Y100 Z100 F6000\n"
         "T0\nG4 S1"
-        #if EXTRUDERS > 1
-          "\nT1\nG4 S1"
-        #endif
+        TERN_(HAS_MULTI_EXTRUDER, "\nT1\nG4 S1")
         "\nG0 X150 Y150 Z150"
       ));
     }

Marlin/src/lcd/extui/lib/mks_ui/draw_change_speed.cpp

           //planner.flow_percentage[1] = planner.flow_percentage[0];
           //planner.e_factor[1]= planner.flow_percentage[1]*0.01;
           planner.refresh_e_factor(0);
-          if (EXTRUDERS == 2) {
+          #if HAS_MULTI_EXTRUDER
             planner.flow_percentage[1] = planner.flow_percentage[0];
             planner.refresh_e_factor(1);
           }

Marlin/src/lcd/extui/lib/mks_ui/draw_dialog.cpp

             //saved_feedrate_percentage = feedrate_percentage;
             planner.flow_percentage[0] = 100;
             planner.e_factor[0]        = planner.flow_percentage[0] * 0.01f;
-            #if EXTRUDERS == 2
+            #if HAS_MULTI_EXTRUDER
               planner.flow_percentage[1] = 100;
               planner.e_factor[1]        = planner.flow_percentage[1] * 0.01f;
             #endif

Marlin/src/lcd/extui/lib/mks_ui/draw_extrusion.cpp

         // nothing to do
       }
       else if (event == LV_EVENT_RELEASED) {
-        if (EXTRUDERS == 2) {
+        if (ENABLED(HAS_MULTI_EXTRUDER)) {
           if (uiCfg.curSprayerChoose == 0) {
             uiCfg.curSprayerChoose = 1;
             queue.inject_P(PSTR("T1"));

Marlin/src/lcd/extui/lib/mks_ui/draw_preHeat.cpp

               thermalManager.start_watching_hotend(uiCfg.curSprayerChoose);
             }
           }
-          #if !defined(SINGLENOZZLE) && EXTRUDERS >= 2
+          #if !defined(SINGLENOZZLE) && HAS_MULTI_EXTRUDER
             else if ((int)thermalManager.temp_hotend[uiCfg.curSprayerChoose].target > (HEATER_1_MAXTEMP - (WATCH_TEMP_INCREASE + TEMP_HYSTERESIS + 1))) {
               thermalManager.temp_hotend[uiCfg.curSprayerChoose].target = (float)HEATER_1_MAXTEMP - (WATCH_TEMP_INCREASE + TEMP_HYSTERESIS + 1);
               thermalManager.start_watching_hotend(uiCfg.curSprayerChoose);
       }
       else if (event == LV_EVENT_RELEASED) {
         if (uiCfg.curTempType == 0) {
-          if (EXTRUDERS == 2) {
+          if (ENABLED(HAS_MULTI_EXTRUDER)) {
             if (uiCfg.curSprayerChoose == 0) {
               uiCfg.curSprayerChoose = 1;
             }

Marlin/src/lcd/extui/lib/mks_ui/draw_printing.cpp

   #endif // if 1
 
   lv_obj_set_pos(buttonExt1, 205, 136);
-  if (EXTRUDERS == 2)
+
+  #if HAS_MULTI_EXTRUDER
     lv_obj_set_pos(buttonExt2, 350, 136);
+  #endif
 
   #if HAS_HEATED_BED
     lv_obj_set_pos(buttonBedstate, 205, 186);
   lv_obj_set_style(labelExt1, &tft_style_label_rel);
   lv_obj_set_pos(labelExt1, 250, 146);
 
-  if (EXTRUDERS == 2) {
+  #if HAS_MULTI_EXTRUDER
     labelExt2 = lv_label_create(scr, NULL);
     lv_obj_set_style(labelExt2, &tft_style_label_rel);
     lv_obj_set_pos(labelExt2, 395, 146);
-  }
+  #endif
 
   #if HAS_HEATED_BED
     labelBed = lv_label_create(scr, NULL);
   sprintf(public_buf_l, printing_menu.temp1, (int)thermalManager.temp_hotend[0].celsius, (int)thermalManager.temp_hotend[0].target);
   lv_label_set_text(labelExt1, public_buf_l);
 
-  if (EXTRUDERS == 2) {
+  #if HAS_MULTI_EXTRUDER
     ZERO(public_buf_l);
     sprintf(public_buf_l, printing_menu.temp1, (int)thermalManager.temp_hotend[1].celsius, (int)thermalManager.temp_hotend[1].target);
     lv_label_set_text(labelExt2, public_buf_l);
-  }
+  #endif
 }
 
 void disp_bed_temp() {

Marlin/src/lcd/extui/ui_api.cpp

   #include "../../libs/numtostr.h"
 #endif
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   #include "../../module/tool_change.h"
 #endif
 
   }
 
   void setActiveTool(const extruder_t extruder, bool no_move) {
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       const uint8_t e = extruder - E0;
       if (e != active_extruder) tool_change(e, no_move);
       active_extruder = e;
      */
     void smartAdjustAxis_steps(const int16_t steps, const axis_t axis, bool linked_nozzles) {
       const float mm = steps * planner.steps_to_mm[axis];
+      UNUSED(mm);
 
       if (!babystepAxis_steps(steps, axis)) return;
 
       #if ENABLED(BABYSTEP_ZPROBE_OFFSET)
         // Make it so babystepping in Z adjusts the Z probe offset.
-        if (axis == Z
-          #if EXTRUDERS > 1
-            && (linked_nozzles || active_extruder == 0)
-          #endif
-        ) probe.offset.z += mm;
-      #else
-        UNUSED(mm);
+        if (axis == Z && TERN1(HAS_MULTI_EXTRUDER, linked_nozzles || active_extruder == 0))
+          probe.offset.z += mm;
       #endif
 
-      #if EXTRUDERS > 1 && HAS_HOTEND_OFFSET
+      #if HAS_MULTI_EXTRUDER && HAS_HOTEND_OFFSET
         /**
          * When linked_nozzles is false, as an axis is babystepped
          * adjust the hotend offsets so that the other nozzles are
         }
       #else
         UNUSED(linked_nozzles);
-        UNUSED(mm);
       #endif
     }
 

Marlin/src/lcd/menu/menu_advanced.cpp

     #if ENABLED(LIN_ADVANCE)
       #if EXTRUDERS == 1
         EDIT_ITEM(float42_52, MSG_ADVANCE_K, &planner.extruder_advance_K[0], 0, 999);
-      #elif EXTRUDERS > 1
+      #elif HAS_MULTI_EXTRUDER
         LOOP_L_N(n, EXTRUDERS)
           EDIT_ITEM_N(float42_52, n, MSG_ADVANCE_K_E, &planner.extruder_advance_K[n], 0, 999);
       #endif
 
       #if ENABLED(VOLUMETRIC_EXTRUDER_LIMIT)
         EDIT_ITEM_FAST(float42_52, MSG_VOLUMETRIC_LIMIT, &planner.volumetric_extruder_limit[active_extruder], 0.0f, 20.0f, planner.calculate_volumetric_extruder_limits);
-        #if EXTRUDERS > 1
+        #if HAS_MULTI_EXTRUDER
           LOOP_L_N(n, EXTRUDERS)
             EDIT_ITEM_FAST_N(float42_52, n, MSG_VOLUMETRIC_LIMIT_E, &planner.volumetric_extruder_limit[n], 0.0f, 20.00f, planner.calculate_volumetric_extruder_limits);
         #endif
 
       if (parser.volumetric_enabled) {
         EDIT_ITEM_FAST(float43, MSG_FILAMENT_DIAM, &planner.filament_size[active_extruder], 1.5f, 3.25f, planner.calculate_volumetric_multipliers);
-        #if EXTRUDERS > 1
+        #if HAS_MULTI_EXTRUDER
           LOOP_L_N(n, EXTRUDERS)
             EDIT_ITEM_FAST_N(float43, n, MSG_FILAMENT_DIAM_E, &planner.filament_size[n], 1.5f, 3.25f, planner.calculate_volumetric_multipliers);
         #endif
       constexpr float extrude_maxlength = TERN(PREVENT_LENGTHY_EXTRUDE, EXTRUDE_MAXLENGTH, 999);
 
       EDIT_ITEM_FAST(float3, MSG_FILAMENT_UNLOAD, &fc_settings[active_extruder].unload_length, 0, extrude_maxlength);
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         LOOP_L_N(n, EXTRUDERS)
           EDIT_ITEM_FAST_N(float3, n, MSG_FILAMENTUNLOAD_E, &fc_settings[n].unload_length, 0, extrude_maxlength);
       #endif
 
       EDIT_ITEM_FAST(float3, MSG_FILAMENT_LOAD, &fc_settings[active_extruder].load_length, 0, extrude_maxlength);
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         LOOP_L_N(n, EXTRUDERS)
           EDIT_ITEM_FAST_N(float3, n, MSG_FILAMENTLOAD_E, &fc_settings[n].load_length, 0, extrude_maxlength);
       #endif
   #elif ENABLED(LIN_ADVANCE)
     #if EXTRUDERS == 1
       EDIT_ITEM(float42_52, MSG_ADVANCE_K, &planner.extruder_advance_K[0], 0, 999);
-    #elif EXTRUDERS > 1
+    #elif HAS_MULTI_EXTRUDER
       LOOP_L_N(n, E_STEPPERS)
         EDIT_ITEM_N(float42_52, n, MSG_ADVANCE_K_E, &planner.extruder_advance_K[n], 0, 999);
     #endif

Marlin/src/lcd/menu/menu_configuration.cpp

 
 #endif
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
 
   #include "../../module/tool_change.h"
 
       EDIT_ITEM(bool, MSG_AUTORETRACT, &fwretract.autoretract_enabled, fwretract.refresh_autoretract);
     #endif
     EDIT_ITEM(float52sign, MSG_CONTROL_RETRACT, &fwretract.settings.retract_length, 0, 100);
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       EDIT_ITEM(float52sign, MSG_CONTROL_RETRACT_SWAP, &fwretract.settings.swap_retract_length, 0, 100);
     #endif
     EDIT_ITEM(float3, MSG_CONTROL_RETRACTF, &fwretract.settings.retract_feedrate_mm_s, 1, 999);
     EDIT_ITEM(float52sign, MSG_CONTROL_RETRACT_ZHOP, &fwretract.settings.retract_zraise, 0, 999);
     EDIT_ITEM(float52sign, MSG_CONTROL_RETRACT_RECOVER, &fwretract.settings.retract_recover_extra, -100, 100);
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       EDIT_ITEM(float52sign, MSG_CONTROL_RETRACT_RECOVER_SWAP, &fwretract.settings.swap_retract_recover_extra, -100, 100);
     #endif
     EDIT_ITEM(float3, MSG_CONTROL_RETRACT_RECOVERF, &fwretract.settings.retract_recover_feedrate_mm_s, 1, 999);
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       EDIT_ITEM(float3, MSG_CONTROL_RETRACT_RECOVER_SWAPF, &fwretract.settings.swap_retract_recover_feedrate_mm_s, 1, 999);
     #endif
     END_MENU();
   //
   // Set single nozzle filament retract and prime length
   //
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     SUBMENU(MSG_TOOL_CHANGE, menu_tool_change);
     #if ENABLED(TOOLCHANGE_MIGRATION_FEATURE)
       SUBMENU(MSG_TOOL_MIGRATION, menu_toolchange_migration);

Marlin/src/lcd/menu/menu_tune.cpp

   #if EXTRUDERS
     EDIT_ITEM(int3, MSG_FLOW, &planner.flow_percentage[active_extruder], 10, 999, []{ planner.refresh_e_factor(active_extruder); });
     // Flow En:
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       LOOP_L_N(n, EXTRUDERS)
         EDIT_ITEM_N(int3, n, MSG_FLOW_N, &planner.flow_percentage[n], 10, 999, []{ planner.refresh_e_factor(MenuItemBase::itemIndex); });
     #endif
   #if ENABLED(LIN_ADVANCE) && DISABLED(SLIM_LCD_MENUS)
     #if EXTRUDERS == 1
       EDIT_ITEM(float42_52, MSG_ADVANCE_K, &planner.extruder_advance_K[0], 0, 999);
-    #elif EXTRUDERS > 1
+    #elif HAS_MULTI_EXTRUDER
       LOOP_L_N(n, EXTRUDERS)
         EDIT_ITEM_N(float42_52, n, MSG_ADVANCE_K_E, &planner.extruder_advance_K[n], 0, 999);
     #endif

Marlin/src/lcd/ultralcd.cpp

 
       #if IS_KINEMATIC
 
-        #if EXTRUDERS > 1
+        #if HAS_MULTI_EXTRUDER
           const int8_t old_extruder = active_extruder;
           if (axis == E_AXIS) active_extruder = e_index;
         #endif
         prepare_internal_move_to_destination(fr_mm_s);  // will set current_position from destination
         processing = false;
 
-        #if EXTRUDERS > 1
-          active_extruder = old_extruder;
-        #endif
+        TERN_(HAS_MULTI_EXTRUDER, active_extruder = old_extruder);
 
       #else
 

Marlin/src/module/endstops.cpp

 
   // With Dual X, endstops are only checked in the homing direction for the active extruder
   #if ENABLED(DUAL_X_CARRIAGE)
-    #define E0_ACTIVE stepper.movement_extruder() == 0
+    #define E0_ACTIVE stepper.last_moved_extruder == 0
     #define X_MIN_TEST() ((X_HOME_DIR < 0 && E0_ACTIVE) || (X2_HOME_DIR < 0 && !E0_ACTIVE))
     #define X_MAX_TEST() ((X_HOME_DIR > 0 && E0_ACTIVE) || (X2_HOME_DIR > 0 && !E0_ACTIVE))
   #else

Marlin/src/module/motion.cpp

 #endif
 
 // The active extruder (tool). Set with T<extruder> command.
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   uint8_t active_extruder = 0; // = 0
 #endif
 

Marlin/src/module/motion.h

 extern int16_t feedrate_percentage;
 
 // The active extruder (tool). Set with T<extruder> command.
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   extern uint8_t active_extruder;
 #else
   constexpr uint8_t active_extruder = 0;

Marlin/src/module/planner.cpp

     block->e_to_p_pressure = baricuda_e_to_p_pressure;
   #endif
 
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     block->extruder = extruder;
   #endif
 
       FANS_LOOP(i) block->fan_speed[i] = thermalManager.fan_speed[i];
     #endif
 
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       block->extruder = extruder;
     #endif
 

Marlin/src/module/planner.h

   };
   uint32_t step_event_count;                // The number of step events required to complete this block
 
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     uint8_t extruder;                       // The extruder to move (if E move)
   #else
     static constexpr uint8_t extruder = 0;

Marlin/src/module/settings.cpp

   extern float other_extruder_advance_K[EXTRUDERS];
 #endif
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   #include "tool_change.h"
   void M217_report(const bool eeprom);
 #endif
   //
   // Tool-change settings
   //
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     toolchange_settings_t toolchange_settings;          // M217 S P R
   #endif
 
     // Multiple Extruders
     //
 
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       _FIELD_TEST(toolchange_settings);
       EEPROM_WRITE(toolchange_settings);
     #endif
       //
       // Tool-change settings
       //
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         _FIELD_TEST(toolchange_settings);
         EEPROM_READ(toolchange_settings);
       #endif
   // Tool-change Settings
   //
 
-  #if EXTRUDERS > 1
+  #if HAS_MULTI_EXTRUDER
     #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)
       toolchange_settings.swap_length     = TOOLCHANGE_FS_LENGTH;
       toolchange_settings.extra_resume    = TOOLCHANGE_FS_EXTRA_RESUME_LENGTH;
       #endif
     #endif
 
-    #if EXTRUDERS > 1
+    #if HAS_MULTI_EXTRUDER
       CONFIG_ECHO_HEADING("Tool-changing:");
       CONFIG_ECHO_START();
       M217_report(true);

Marlin/src/module/stepper.cpp

 
 bool Stepper::abort_current_block;
 
-#if DISABLED(MIXING_EXTRUDER) && EXTRUDERS > 1
+#if DISABLED(MIXING_EXTRUDER) && HAS_MULTI_EXTRUDER
   uint8_t Stepper::last_moved_extruder = 0xFF;
 #endif
 
          Stepper::decelerate_after,          // The count at which to start decelerating
          Stepper::step_event_count;          // The total event count for the current block
 
-#if EXTRUDERS > 1 || ENABLED(MIXING_EXTRUDER)
+#if EITHER(HAS_MULTI_EXTRUDER, MIXING_EXTRUDER)
   uint8_t Stepper::stepper_extruder;
 #else
   constexpr uint8_t Stepper::stepper_extruder;
 #elif ENABLED(DUAL_X_CARRIAGE)
   #define X_APPLY_DIR(v,ALWAYS) do{ \
     if (extruder_duplication_enabled || ALWAYS) { X_DIR_WRITE(v); X2_DIR_WRITE(mirrored_duplication_mode ? !(v) : v); } \
-    else if (movement_extruder()) X2_DIR_WRITE(v); else X_DIR_WRITE(v); \
+    else if (last_moved_extruder) X2_DIR_WRITE(v); else X_DIR_WRITE(v); \
   }while(0)
   #define X_APPLY_STEP(v,ALWAYS) do{ \
     if (extruder_duplication_enabled || ALWAYS) { X_STEP_WRITE(v); X2_STEP_WRITE(v); } \
-    else if (movement_extruder()) X2_STEP_WRITE(v); else X_STEP_WRITE(v); \
+    else if (last_moved_extruder) X2_STEP_WRITE(v); else X_STEP_WRITE(v); \
   }while(0)
 #else
   #define X_APPLY_DIR(v,Q) X_DIR_WRITE(v)
         MIXER_STEPPER_SETUP();
       #endif
 
-      #if EXTRUDERS > 1
+      #if HAS_MULTI_EXTRUDER
         stepper_extruder = current_block->extruder;
       #endif
 
         || TERN(MIXING_EXTRUDER, false, stepper_extruder != last_moved_extruder)
       ) {
         last_direction_bits = current_block->direction_bits;
-        #if EXTRUDERS > 1
+        #if HAS_MULTI_EXTRUDER
           last_moved_extruder = stepper_extruder;
         #endif
 

Marlin/src/module/stepper.h

     static bool abort_current_block;        // Signals to the stepper that current block should be aborted
 
     // Last-moved extruder, as set when the last movement was fetched from planner
-    #if EXTRUDERS < 2
-      static constexpr uint8_t last_moved_extruder = 0;
-    #elif DISABLED(MIXING_EXTRUDER)
+    #if HAS_MULTI_EXTRUDER
       static uint8_t last_moved_extruder;
+    #else
+      static constexpr uint8_t last_moved_extruder = 0;
     #endif
 
     #if ENABLED(X_DUAL_ENDSTOPS)
                     decelerate_after,       // The point from where we need to start decelerating
                     step_event_count;       // The total event count for the current block
 
-    #if EXTRUDERS > 1 || ENABLED(MIXING_EXTRUDER)
+    #if EITHER(HAS_MULTI_EXTRUDER, MIXING_EXTRUDER)
       static uint8_t stepper_extruder;
     #else
       static constexpr uint8_t stepper_extruder = 0;
     // The last movement direction was not null on the specified axis. Note that motor direction is not necessarily the same.
     FORCE_INLINE static bool axis_is_moving(const AxisEnum axis) { return TEST(axis_did_move, axis); }
 
-    // The extruder associated to the last movement
-    FORCE_INLINE static uint8_t movement_extruder() {
-      return (EXTRUDERS > 1 && DISABLED(MIXING_EXTRUDER)) ? last_moved_extruder : 0;
-    }
-
     // Handle a triggered endstop
     static void endstop_triggered(const AxisEnum axis);
 

Marlin/src/module/tool_change.cpp

 #define DEBUG_OUT ENABLED(DEBUG_TOOL_CHANGE)
 #include "../core/debug_out.h"
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
   toolchange_settings_t toolchange_settings;  // Initialized by settings.load()
 #endif
 
     if (new_tool) invalid_extruder_error(new_tool);
     return;
 
-  #else // EXTRUDERS > 1
+  #elif HAS_MULTI_EXTRUDER
 
     planner.synchronize();
 
     SERIAL_ECHO_START();
     SERIAL_ECHOLNPAIR(STR_ACTIVE_EXTRUDER, int(active_extruder));
 
-  #endif // EXTRUDERS > 1
+  #endif // HAS_MULTI_EXTRUDER
 }
 
 #if ENABLED(TOOLCHANGE_MIGRATION_FEATURE)

Marlin/src/module/tool_change.h

 #include "../inc/MarlinConfigPre.h"
 #include "../core/types.h"
 
-#if EXTRUDERS > 1
+#if HAS_MULTI_EXTRUDER
 
   typedef struct {
     #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)

Marlin/src/pins/sensitive_pins.h

     #endif
   #endif
 
-#elif EXTRUDERS > 1 || ENABLED(MIXING_EXTRUDER)
+#elif EITHER(HAS_MULTI_EXTRUDER, MIXING_EXTRUDER)
 
   #undef _E1_PINS
   #define _E1_PINS E1_STEP_PIN, E1_DIR_PIN, E1_ENABLE_PIN, _E1_CS _E1_MS1 _E1_MS2 _E1_MS3
     #endif // EXTRUDERS > 3 || MIXING_EXTRUDER > 3
   #endif // EXTRUDERS > 2 || MIXING_EXTRUDER > 2
 
-#endif // EXTRUDERS > 1 || MIXING_EXTRUDER
+#endif // HAS_MULTI_EXTRUDER || MIXING_EXTRUDER
 
 //
 // Heaters, Fans, Temp Sensors

buildroot/share/PlatformIO/scripts/common-dependencies.h

 
 #if EXTRUDERS
   #define HAS_EXTRUDERS
-  #if EXTRUDERS > 1
-    #define HAS_MULTI_EXTRUDER
-  #endif
 #endif
 
 #if HAS_LCD_MENU