Cleanup and consolidate probe conditionals for clarity

Marlin/Conditionals.h

   #define HAS_Z_MAX (PIN_EXISTS(Z_MAX))
   #define HAS_Z2_MIN (PIN_EXISTS(Z2_MIN))
   #define HAS_Z2_MAX (PIN_EXISTS(Z2_MAX))
-  #define HAS_Z_PROBE (PIN_EXISTS(Z_MIN_PROBE))
+  #define HAS_Z_MIN_PROBE_PIN (PIN_EXISTS(Z_MIN_PROBE))
   #define HAS_SOLENOID_1 (PIN_EXISTS(SOL1))
   #define HAS_SOLENOID_2 (PIN_EXISTS(SOL2))
   #define HAS_SOLENOID_3 (PIN_EXISTS(SOL3))
     #endif
   #endif
 
-  #if  ( (HAS_Z_MIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)) || HAS_Z_PROBE ) \
-    && ( \
-         ENABLED(FIX_MOUNTED_PROBE) \
-      || ENABLED(MECHANICAL_PROBE) \
-      || HAS_Z_ENDSTOP_SERVO \
-      || ENABLED(Z_PROBE_ALLEN_KEY) \
-      || ENABLED(Z_PROBE_SLED) \
-    )
-    #define HAS_Z_MIN_PROBE
-  #endif
+  #define PROBE_SELECTED (ENABLED(FIX_MOUNTED_PROBE) || ENABLED(MECHANICAL_PROBE) || HAS_Z_ENDSTOP_SERVO || ENABLED(Z_PROBE_SLED))
+
+  #define PROBE_PIN_CONFIGURED (HAS_Z_MIN_PROBE_PIN || (HAS_Z_MIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)))
+
+  #define HAS_BED_PROBE (PROBE_SELECTED && PROBE_PIN_CONFIGURED)
 
   /**
    * Delta radius/rod trimmers

Marlin/Marlin_main.cpp

     refresh_cmd_timeout();
   }
 
-  #if ENABLED(HAS_Z_MIN_PROBE)
+  #if HAS_BED_PROBE
 
   static void deploy_z_probe() {
 
 
     endstops.enable_z_probe(false);
   }
-  #endif // HAS_Z_MIN_PROBE
+  #endif // HAS_BED_PROBE
 
   enum ProbeAction {
     ProbeStay          = 0,
         }
       #endif
       enqueue_and_echo_commands_P(PSTR(Z_PROBE_END_SCRIPT));
-      #if ENABLED(HAS_Z_MIN_PROBE)
+      #if HAS_BED_PROBE
         endstops.enable_z_probe(false);
       #endif
       stepper.synchronize();
    *  Z_MIN_PROBE_PIN, but here for clarity.
    */
   #if ENABLED(Z_MIN_PROBE_ENDSTOP)
-    #if !HAS_Z_PROBE
+    #if !HAS_Z_MIN_PROBE_PIN
       #error You must define Z_MIN_PROBE_PIN to enable Z probe repeatability calculation.
     #endif
   #elif !HAS_Z_MIN

Marlin/SanityCheck.h

  * Probes
  */
 
-/**
- * A probe needs a pin
- */
-#if (!((HAS_Z_MIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)) || HAS_Z_PROBE )) && ( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(MECHANICAL_PROBE) || ENABLED(Z_PROBE_SLED))
-  #error A probe needs a pin! [Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN || HAS_Z_PROBE]
-#endif
+#if PROBE_SELECTED
 
-#if ((HAS_Z_MIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)) && HAS_Z_PROBE) && ( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(MECHANICAL_PROBE) || ENABLED(Z_PROBE_SLED))
-  #error A probe should not be connected to more than one pin! [Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN || HAS_Z_PROBE]
-#endif
+  /**
+   * A probe needs a pin
+   */
+  #if !PROBE_PIN_CONFIGURED
+    #error A probe needs a pin! Use Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN or Z_MIN_PROBE_PIN.
+  #endif
 
-/**
-  * Require one kind of probe
-  */
-#if ENABLED(AUTO_BED_LEVELING_FEATURE) && !( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(MECHANICAL_PROBE) || ENABLED(Z_PROBE_SLED))
-  #error For AUTO_BED_LEVELING_FEATURE define one kind of probe! [Servo | MECHANICAL_PROBE | Z_PROBE_SLED | FIX_MOUNTED_PROBE]
-#endif
+  /**
+   * Z_MIN_PIN and Z_MIN_PROBE_PIN can't co-exist when Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+   */
+  #if HAS_Z_MIN && HAS_Z_MIN_PROBE_PIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)
+    #error A probe cannot have more than one pin! Use Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN or Z_MIN_PROBE_PIN.
+  #endif
 
-// To do: Fail with more than one probe defined
+  /**
+   * Make sure the plug is enabled if it's used
+   */
+  #if ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && DISABLED(USE_ZMIN_PLUG)
+    #error You must enable USE_ZMIN_PLUG if any probe or endstop is connected to the ZMIN plug.
+  #endif
 
-/**
- * Auto Bed Leveling
- */
-#if ENABLED(AUTO_BED_LEVELING_FEATURE)
+  /**
+   * Only allow one probe option to be defined
+   */
+  #if (ENABLED(FIX_MOUNTED_PROBE) && (ENABLED(MECHANICAL_PROBE) || HAS_Z_ENDSTOP_SERVO || ENABLED(Z_PROBE_SLED))) \
+       || (ENABLED(MECHANICAL_PROBE) && (HAS_Z_ENDSTOP_SERVO || ENABLED(Z_PROBE_SLED))) \
+       || (HAS_Z_ENDSTOP_SERVO && ENABLED(Z_PROBE_SLED))
+    #error Please define only one type of probe: Z Servo, MECHANICAL_PROBE, Z_PROBE_SLED, or FIX_MOUNTED_PROBE.
+  #endif
 
   /**
-   * Require a Z min pin
+   * Don't allow nonsense probe-pin settings
    */
-  #if !PIN_EXISTS(Z_MIN)
-    #if !PIN_EXISTS(Z_MIN_PROBE) || (DISABLED(Z_MIN_PROBE_ENDSTOP) || ENABLED(DISABLE_Z_MIN_PROBE_ENDSTOP)) // It's possible for someone to set a pin for the Z probe, but not enable it.
-      #if ENABLED(Z_MIN_PROBE_REPEATABILITY_TEST)
-        #error You must have a Z_MIN or Z_PROBE endstop to enable Z_MIN_PROBE_REPEATABILITY_TEST.
-      #else
-        #error AUTO_BED_LEVELING_FEATURE requires a Z_MIN or Z_PROBE endstop. Z_MIN_PIN or Z_MIN_PROBE_PIN must point to a valid hardware pin.
-      #endif
-    #endif
+  #if ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(Z_MIN_PROBE_ENDSTOP)
+    #error You can't enable both Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN and Z_MIN_PROBE_ENDSTOP.
+  #elif ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(DISABLE_Z_MIN_PROBE_ENDSTOP)
+    #error Don't enable DISABLE_Z_MIN_PROBE_ENDSTOP with Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN.
+  #elif ENABLED(DISABLE_Z_MIN_PROBE_ENDSTOP) && DISABLED(Z_MIN_PROBE_ENDSTOP)
+    #error DISABLE_Z_MIN_PROBE_ENDSTOP requires Z_MIN_PROBE_ENDSTOP to be set.
   #endif
 
   /**
    * Require a Z probe pin if Z_MIN_PROBE_ENDSTOP is enabled.
    */
   #if ENABLED(Z_MIN_PROBE_ENDSTOP)
-    #if !PIN_EXISTS(Z_MIN_PROBE)
-      #error You must have a Z_MIN_PROBE_PIN defined in your pins_XXXX.h file if you enable Z_MIN_PROBE_ENDSTOP.
+    #if !HAS_Z_MIN_PROBE_PIN
+      #error Z_MIN_PROBE_ENDSTOP requires a Z_MIN_PROBE_PIN in your board's pins_XXXX.h file.
     #endif
     // Forcing Servo definitions can break some hall effect sensor setups. Leaving these here for further comment.
     //#ifndef NUM_SERVOS
     //  #error You must have SERVO_ENDSTOP_ANGLES defined for Z Extend and Retract to use Z_MIN_PROBE_ENDSTOP.
     //#endif
   #endif
+
+#else
+
+  /**
+   * Require some kind of probe for bed leveling
+   */
+  #if ENABLED(AUTO_BED_LEVELING_FEATURE)
+    #error AUTO_BED_LEVELING_FEATURE requires a probe! Define a Z Servo, MECHANICAL_PROBE, Z_PROBE_SLED, or FIX_MOUNTED_PROBE.
+  #endif
+
+#endif
+
+/**
+ * Auto Bed Leveling
+ */
+#if ENABLED(AUTO_BED_LEVELING_FEATURE)
+
+  /**
+   * Require a Z min pin
+   */
+  #if !PIN_EXISTS(Z_MIN)
+    #if !PIN_EXISTS(Z_MIN_PROBE) || (DISABLED(Z_MIN_PROBE_ENDSTOP) || ENABLED(DISABLE_Z_MIN_PROBE_ENDSTOP)) // It's possible for someone to set a pin for the Z probe, but not enable it.
+      #if ENABLED(Z_MIN_PROBE_REPEATABILITY_TEST)
+        #error You must have a Z_MIN or Z_PROBE endstop to enable Z_MIN_PROBE_REPEATABILITY_TEST.
+      #else
+        #error AUTO_BED_LEVELING_FEATURE requires a Z_MIN or Z_PROBE endstop. Z_MIN_PIN or Z_MIN_PROBE_PIN must point to a valid hardware pin.
+      #endif
+    #endif
+  #endif
+
   /**
    * Check if Probe_Offset * Grid Points is greater than Probing Range
    */

Marlin/endstops.cpp

     #endif
   );
   enable(true);
-  #if ENABLED(HAS_Z_MIN_PROBE)
+  #if HAS_BED_PROBE
     enable_z_probe(false);
   #endif
 } // Endstops::Endstops
     #endif
   #endif
 
-  #if HAS_Z_PROBE && ENABLED(Z_MIN_PROBE_ENDSTOP) // Check for Z_MIN_PROBE_ENDSTOP so we don't pull a pin high unless it's to be used.
+  #if HAS_Z_MIN_PROBE_PIN && ENABLED(Z_MIN_PROBE_ENDSTOP) // Check for Z_MIN_PROBE_ENDSTOP so we don't pull a pin high unless it's to be used.
     SET_INPUT(Z_MIN_PROBE_PIN);
     #if ENABLED(ENDSTOPPULLUP_ZMIN_PROBE)
       WRITE(Z_MIN_PROBE_PIN,HIGH);
     SERIAL_PROTOCOLPGM(MSG_Z2_MAX);
     SERIAL_PROTOCOLLN(((READ(Z2_MAX_PIN)^Z2_MAX_ENDSTOP_INVERTING) ? MSG_ENDSTOP_HIT : MSG_ENDSTOP_OPEN));
   #endif
-  #if HAS_Z_PROBE
+  #if HAS_Z_MIN_PROBE_PIN
     SERIAL_PROTOCOLPGM(MSG_Z_PROBE);
     SERIAL_PROTOCOLLN(((READ(Z_MIN_PROBE_PIN)^Z_MIN_PROBE_ENDSTOP_INVERTING) ? MSG_ENDSTOP_HIT : MSG_ENDSTOP_OPEN));
   #endif
 
           #else // !Z_DUAL_ENDSTOPS
 
-            #if ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
+            #if HAS_BED_PROBE && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)
               if (z_probe_enabled) UPDATE_ENDSTOP(Z, MIN);
             #else
               UPDATE_ENDSTOP(Z, MIN);
 
         #endif // HAS_Z_MIN
 
-        #if ENABLED(Z_MIN_PROBE_ENDSTOP) && DISABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
+        #if HAS_BED_PROBE && ENABLED(Z_MIN_PROBE_ENDSTOP) && DISABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)
           if (z_probe_enabled) {
             UPDATE_ENDSTOP(Z, MIN_PROBE);
             if (TEST_ENDSTOP(Z_MIN_PROBE)) SBI(endstop_hit_bits, Z_MIN_PROBE);

Marlin/endstops.h

     FORCE_INLINE void hit_on_purpose() { endstop_hit_bits = 0; }
 
     // Enable / disable endstop z-probe checking
-    #if ENABLED(HAS_Z_MIN_PROBE)
+    #if HAS_BED_PROBE
       volatile bool z_probe_enabled = false;
       FORCE_INLINE void enable_z_probe(bool onoff=true) { z_probe_enabled = onoff; }
     #endif

Marlin/stepper.cpp

   if (current_block != NULL) {
 
     // Update endstops state, if enabled
-    #if ENABLED(HAS_Z_MIN_PROBE)
+    #if HAS_BED_PROBE
       if (endstops.enabled || endstops.z_probe_enabled) endstops.update();
     #else
       if (endstops.enabled) endstops.update();