♻️ Refactor, comment endstop/probe enums

Marlin/src/lcd/menu/menu_bed_corners.cpp

     if (verify) do_blocking_move_to_z(current_position.z + LEVEL_CORNERS_Z_HOP); // do clearance if needed
     TERN_(BLTOUCH_SLOW_MODE, bltouch.deploy()); // Deploy in LOW SPEED MODE on every probe action
     do_blocking_move_to_z(last_z - LEVEL_CORNERS_PROBE_TOLERANCE, MMM_TO_MMS(Z_PROBE_FEEDRATE_SLOW)); // Move down to lower tolerance
-    if (TEST(endstops.trigger_state(), TERN(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN, Z_MIN, Z_MIN_PROBE))) { // check if probe triggered
+    if (TEST(endstops.trigger_state(), Z_MIN_PROBE)) { // check if probe triggered
       endstops.hit_on_purpose();
       set_current_from_steppers_for_axis(Z_AXIS);
       sync_plan_position();

Marlin/src/module/endstops.cpp

   }
 }
 
+#if GCC_VERSION <= 50000
+  #pragma GCC diagnostic push
+  #pragma GCC diagnostic ignored "-Wunused-function"
+#endif
+
 static void print_es_state(const bool is_hit, PGM_P const label=nullptr) {
   if (label) SERIAL_ECHOPGM_P(label);
   SERIAL_ECHOPGM(": ");
   SERIAL_ECHOLNPGM_P(is_hit ? PSTR(STR_ENDSTOP_HIT) : PSTR(STR_ENDSTOP_OPEN));
 }
 
+#if GCC_VERSION <= 50000
+  #pragma GCC diagnostic pop
+#endif
+
 void _O2 Endstops::report_states() {
   TERN_(BLTOUCH, bltouch._set_SW_mode());
   SERIAL_ECHOLNPGM(STR_M119_REPORT);

Marlin/src/module/endstops.h

 #define _ES_ITEM(K,N) TERN_(K,DEFER4(__ES_ITEM)(N))
 
 enum EndstopEnum : char {
+  // Common XYZ (ABC) endstops. Defined according to USE_[XYZ](MIN|MAX)_PLUG settings.
   _ES_ITEM(HAS_X_MIN, X_MIN)
   _ES_ITEM(HAS_X_MAX, X_MAX)
   _ES_ITEM(HAS_Y_MIN, Y_MIN)
   _ES_ITEM(HAS_Y_MAX, Y_MAX)
   _ES_ITEM(HAS_Z_MIN, Z_MIN)
   _ES_ITEM(HAS_Z_MAX, Z_MAX)
+
+  // Extra Endstops for XYZ
   #if ENABLED(X_DUAL_ENDSTOPS)
     _ES_ITEM(HAS_X_MIN, X2_MIN)
     _ES_ITEM(HAS_X_MAX, X2_MAX)
       _ES_ITEM(HAS_Z_MAX, Z4_MAX)
     #endif
   #endif
-  _ES_ITEM(HAS_Z_MIN_PROBE_PIN, Z_MIN_PROBE)
+
+  // Bed Probe state is distinct or shared with Z_MIN (i.e., when the probe is the only Z endstop)
+  _ES_ITEM(HAS_BED_PROBE, Z_MIN_PROBE IF_DISABLED(HAS_CUSTOM_PROBE_PIN, = Z_MIN))
+
+  // The total number of states
   NUM_ENDSTOP_STATES
-};
 
-#define X_ENDSTOP TERN(X_HOME_TO_MAX, X_MAX, X_MIN)
-#define Y_ENDSTOP TERN(Y_HOME_TO_MAX, Y_MAX, Y_MIN)
-#define Z_ENDSTOP TERN(Z_HOME_TO_MAX, Z_MAX, TERN(HOMING_Z_WITH_PROBE, Z_MIN_PROBE, Z_MIN))
+  // Endstops can be either MIN or MAX but not both
+  #if HAS_X_MIN || HAS_X_MAX
+    , X_ENDSTOP = TERN(X_HOME_TO_MAX, X_MAX, X_MIN)
+  #endif
+  #if HAS_Y_MIN || HAS_Y_MAX
+    , Y_ENDSTOP = TERN(Y_HOME_TO_MAX, Y_MAX, Y_MIN)
+  #endif
+  #if HAS_Z_MIN || HAS_Z_MAX
+    , Z_ENDSTOP = TERN(Z_HOME_TO_MAX, Z_MAX, TERN(HOMING_Z_WITH_PROBE, Z_MIN_PROBE, Z_MIN))
+  #endif
+};
 
 #undef __ES_ITEM
 #undef _ES_ITEM

Marlin/src/module/probe.cpp

     #if BOTH(DELTA, SENSORLESS_PROBING)
       endstops.trigger_state() & (_BV(X_MAX) | _BV(Y_MAX) | _BV(Z_MAX))
     #else
-      TEST(endstops.trigger_state(), TERN(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN, Z_MIN, Z_MIN_PROBE))
+      TEST(endstops.trigger_state(), Z_MIN_PROBE)
     #endif
   ;