Restore position_float to fix LIN_ADVANCE

Marlin/src/inc/SanityCheck.h

   #endif
 #endif
 
+#if ENABLED(LIN_ADVANCE) && !IS_CARTESIAN
+  #error "Sorry! LIN_ADVANCE is only compatible with Cartesian."
+#endif
+
 /**
  * Parking Extruder requirements
  */

Marlin/src/module/planner.cpp

 
 #if ENABLED(LIN_ADVANCE)
   float Planner::extruder_advance_k, // Initialized by settings.load()
-        Planner::advance_ed_ratio;   // Initialized by settings.load()
+        Planner::advance_ed_ratio,   // Initialized by settings.load()
+        Planner::position_float[XYZE], // Needed for accurate maths. Steps cannot be used!
+        Planner::lin_dist_xy,
+        Planner::lin_dist_e;
 #endif
 
 #if ENABLED(ULTRA_LCD)
 void Planner::init() {
   block_buffer_head = block_buffer_tail = 0;
   ZERO(position);
+  #if ENABLED(LIN_ADVANCE)
+    ZERO(position_float);
+  #endif
   ZERO(previous_speed);
   previous_nominal_speed = 0.0;
   #if ABL_PLANAR
     SERIAL_ECHOLNPGM(" steps)");
   //*/
 
-  #if ENABLED(PREVENT_COLD_EXTRUSION) || ENABLED(PREVENT_LENGTHY_EXTRUDE)
+  // If LIN_ADVANCE is disabled then do E move prevention with integers
+  // Otherwise it's done in _buffer_segment.
+  #if DISABLED(LIN_ADVANCE) && (ENABLED(PREVENT_COLD_EXTRUSION) || ENABLED(PREVENT_LENGTHY_EXTRUDE))
     if (de) {
       #if ENABLED(PREVENT_COLD_EXTRUSION)
         if (thermalManager.tooColdToExtrude(extruder)) {
         }
       #endif // PREVENT_LENGTHY_EXTRUDE
     }
-  #endif // PREVENT_COLD_EXTRUSION || PREVENT_LENGTHY_EXTRUDE
+  #endif // !LIN_ADVANCE && (PREVENT_COLD_EXTRUSION || PREVENT_LENGTHY_EXTRUDE)
 
   // Compute direction bit-mask for this block
   uint8_t dm = 0;
      *                                      In that case, the retract and move will be executed together.
      *                                      This leads to too many advance steps due to a huge e_acceleration.
      *                                      The math is good, but we must avoid retract moves with advance!
-     * de > 0                             : Extruder is running forward (e.g., for "Wipe while retracting" (Slic3r) or "Combing" (Cura) moves)
+     * lin_dist_e > 0                     : Extruder is running forward (e.g., for "Wipe while retracting" (Slic3r) or "Combing" (Cura) moves)
      */
     block->use_advance_lead =  esteps && (block->steps[X_AXIS] || block->steps[Y_AXIS])
                             && extruder_advance_k
                             && (uint32_t)esteps != block->step_event_count
-                            && de > 0;
+                            && lin_dist_e > 0;
     if (block->use_advance_lead)
       block->abs_adv_steps_multiplier8 = LROUND(
         extruder_advance_k
-        * (UNEAR_ZERO(advance_ed_ratio) ? de * steps_to_mm[E_AXIS_N] / HYPOT(da * steps_to_mm[X_AXIS], db * steps_to_mm[Y_AXIS]) : advance_ed_ratio) // Use the fixed ratio, if set
+        * (UNEAR_ZERO(advance_ed_ratio) ? lin_dist_e / lin_dist_xy : advance_ed_ratio) // Use the fixed ratio, if set
         * (block->nominal_speed / (float)block->nominal_rate)
         * axis_steps_per_mm[E_AXIS_N] * 256.0
       );
     SERIAL_ECHOLNPGM(")");
   //*/
 
-  // DRYRUN ignores all temperature constraints and assures that the extruder is instantly satisfied
-  if (DEBUGGING(DRYRUN))
+  // DRYRUN prevents E moves from taking place
+  if (DEBUGGING(DRYRUN)) {
     position[E_AXIS] = target[E_AXIS];
+    #if ENABLED(LIN_ADVANCE)
+      position_float[E_AXIS] = e;
+    #endif
+  }
+
+  #if ENABLED(LIN_ADVANCE)
+    lin_dist_e = e - position_float[E_AXIS];
+  #endif
+
+  // If LIN_ADVANCE is enabled then do E move prevention with floats
+  // Otherwise it's done in _buffer_steps.
+  #if ENABLED(LIN_ADVANCE) && (ENABLED(PREVENT_COLD_EXTRUSION) || ENABLED(PREVENT_LENGTHY_EXTRUDE))
+    if (lin_dist_e) {
+      #if ENABLED(PREVENT_COLD_EXTRUSION)
+        if (thermalManager.tooColdToExtrude(extruder)) {
+          position_float[E_AXIS] = e; // Behave as if the move really took place, but ignore E part
+          position[E_AXIS] = target[E_AXIS];
+          lin_dist_e = 0;
+          SERIAL_ECHO_START();
+          SERIAL_ECHOLNPGM(MSG_ERR_COLD_EXTRUDE_STOP);
+        }
+      #endif // PREVENT_COLD_EXTRUSION
+      #if ENABLED(PREVENT_LENGTHY_EXTRUDE)
+        if (lin_dist_e * e_factor[extruder] > (EXTRUDE_MAXLENGTH)) {
+          position_float[E_AXIS] = e; // Behave as if the move really took place, but ignore E part
+          position[E_AXIS] = target[E_AXIS];
+          lin_dist_e = 0;
+          SERIAL_ECHO_START();
+          SERIAL_ECHOLNPGM(MSG_ERR_LONG_EXTRUDE_STOP);
+        }
+      #endif // PREVENT_LENGTHY_EXTRUDE
+    }
+  #endif // LIN_ADVANCE && (PREVENT_COLD_EXTRUSION || PREVENT_LENGTHY_EXTRUDE)
+
+  #if ENABLED(LIN_ADVANCE)
+    if (lin_dist_e > 0)
+      lin_dist_xy = HYPOT(a - position_float[X_AXIS], b - position_float[Y_AXIS]);
+  #endif
 
   // Always split the first move into two (if not homing or probing)
   if (!blocks_queued()) {
+
     #define _BETWEEN(A) (position[A##_AXIS] + target[A##_AXIS]) >> 1
     const int32_t between[XYZE] = { _BETWEEN(X), _BETWEEN(Y), _BETWEEN(Z), _BETWEEN(E) };
     DISABLE_STEPPER_DRIVER_INTERRUPT();
+
+    #if ENABLED(LIN_ADVANCE)
+      lin_dist_xy *= 0.5;
+      lin_dist_e *= 0.5;
+    #endif
+
     _buffer_steps(between, fr_mm_s, extruder);
+
+    #if ENABLED(LIN_ADVANCE)
+      position_float[X_AXIS] = (position_float[X_AXIS] + a) * 0.5;
+      position_float[Y_AXIS] = (position_float[Y_AXIS] + b) * 0.5;
+      //position_float[Z_AXIS] = (position_float[Z_AXIS] + c) * 0.5;
+      position_float[E_AXIS] = (position_float[E_AXIS] + e) * 0.5;
+    #endif
+
     const uint8_t next = block_buffer_head;
     _buffer_steps(target, fr_mm_s, extruder);
     SBI(block_buffer[next].flag, BLOCK_BIT_CONTINUED);
 
   stepper.wake_up();
 
+  #if ENABLED(LIN_ADVANCE)
+    position_float[X_AXIS] = a;
+    position_float[Y_AXIS] = b;
+    //position_float[Z_AXIS] = c;
+    position_float[E_AXIS] = e;
+  #endif
 } // buffer_segment()
 
 /**
                 nb = position[Y_AXIS] = LROUND(b * axis_steps_per_mm[Y_AXIS]),
                 nc = position[Z_AXIS] = LROUND(c * axis_steps_per_mm[Z_AXIS]),
                 ne = position[E_AXIS] = LROUND(e * axis_steps_per_mm[_EINDEX]);
+  #if ENABLED(LIN_ADVANCE)
+    position_float[X_AXIS] = a;
+    position_float[Y_AXIS] = b;
+    //position_float[Z_AXIS] = c;
+    position_float[E_AXIS] = e;
+  #endif
   stepper.set_position(na, nb, nc, ne);
   previous_nominal_speed = 0.0; // Resets planner junction speeds. Assumes start from rest.
   ZERO(previous_speed);
  * Sync from the stepper positions. (e.g., after an interrupted move)
  */
 void Planner::sync_from_steppers() {
-  LOOP_XYZE(i)
+  LOOP_XYZE(i) {
     position[i] = stepper.position((AxisEnum)i);
+    #if ENABLED(LIN_ADVANCE)
+      position_float[i] = position[i] * steps_to_mm[i
+        #if ENABLED(DISTINCT_E_FACTORS)
+          + (i == E_AXIS ? active_extruder : 0)
+        #endif
+      ];
+    #endif
+  }
 }
 
 /**
     const uint8_t axis_index = axis;
   #endif
   position[axis] = LROUND(v * axis_steps_per_mm[axis_index]);
+  #if ENABLED(LIN_ADVANCE)
+    position_float[axis] = v;
+  #endif
   stepper.set_position(axis, v);
   previous_speed[axis] = 0.0;
 }

Marlin/src/module/planner.h

     #endif
 
     #if ENABLED(LIN_ADVANCE)
-      static float extruder_advance_k, advance_ed_ratio;
+      static float extruder_advance_k, advance_ed_ratio,
+                   position_float[XYZE],
+                   lin_dist_xy, lin_dist_e;
     #endif
 
     #if ENABLED(SKEW_CORRECTION)