Redo "invalid extruder" to save 264 bytes

- Use `setTargetedHotend` in `M200`, as with other commands that use
`T` for the extruder
- Synthesize the "invalid extruder" message, obviating several long
strings

Marlin/Marlin_main.cpp

@@ -3938,20 +3938,14 @@ inline void gcode_M121() { enable_endstops(false); }
 #endif // BLINKM
 
 /**
- * M200: Set filament diameter and set E axis units to cubic millimeters (use S0 to set back to millimeters).
+ * M200: Set filament diameter and set E axis units to cubic millimeters
- *       T<extruder>
+ *
- *       D<millimeters>
+ *    T<extruder> - Optional extruder number. Current extruder if omitted.
+ *    D<mm> - Diameter of the filament. Use "D0" to set units back to millimeters.
  */
 inline void gcode_M200() {
-  int tmp_extruder = active_extruder;
+
-  if (code_seen('T')) {
+  if (setTargetedHotend(200)) return;
-    tmp_extruder = code_value_short();
-    if (tmp_extruder >= EXTRUDERS) {
-      SERIAL_ECHO_START;
-      SERIAL_ECHO(MSG_M200_INVALID_EXTRUDER);
-      return;
-    }
-  }
 
   if (code_seen('D')) {
     float diameter = code_value();
@@ -3960,7 +3954,7 @@ inline void gcode_M200() {
     // for all extruders
     volumetric_enabled = (diameter != 0.0);
     if (volumetric_enabled) {
-      filament_size[tmp_extruder] = diameter;
+      filament_size[target_extruder] = diameter;
       // make sure all extruders have some sane value for the filament size
       for (int i=0; i<EXTRUDERS; i++)
         if (! filament_size[i]) filament_size[i] = DEFAULT_NOMINAL_FILAMENT_DIA;
@@ -6529,25 +6523,20 @@ bool setTargetedHotend(int code){
   if (code_seen('T')) {
     target_extruder = code_value_short();
     if (target_extruder >= EXTRUDERS) {
-      SERIAL_ECHO_START;
       switch(code) {
         case 104:
-          SERIAL_ECHO(MSG_M104_INVALID_EXTRUDER);
-          break;
         case 105:
-          SERIAL_ECHO(MSG_M105_INVALID_EXTRUDER);
-          break;
         case 109:
-          SERIAL_ECHO(MSG_M109_INVALID_EXTRUDER);
-          break;
         case 218:
-          SERIAL_ECHO(MSG_M218_INVALID_EXTRUDER);
-          break;
         case 221:
-          SERIAL_ECHO(MSG_M221_INVALID_EXTRUDER);
+        case 200:
+          SERIAL_ECHO_START;
+          SERIAL_CHAR('M');
+          SERIAL_ECHO(code);
+          SERIAL_ECHOPGM(" " MSG_INVALID_EXTRUDER " ");
+          SERIAL_ECHOLN(target_extruder);
           break;
       }
-      SERIAL_ECHOLN(target_extruder);
       return true;
     }
   }

Marlin/configurator/config/language.h

@@ -121,12 +121,6 @@
 #define MSG_END_FILE_LIST                   "End file list"
 #define MSG_INVALID_EXTRUDER                "Invalid extruder"
 #define MSG_INVALID_SOLENOID                "Invalid solenoid"
-#define MSG_M104_INVALID_EXTRUDER           "M104 " MSG_INVALID_EXTRUDER " "
-#define MSG_M105_INVALID_EXTRUDER           "M105 " MSG_INVALID_EXTRUDER " "
-#define MSG_M109_INVALID_EXTRUDER           "M109 " MSG_INVALID_EXTRUDER " "
-#define MSG_M200_INVALID_EXTRUDER           "M200 " MSG_INVALID_EXTRUDER " "
-#define MSG_M218_INVALID_EXTRUDER           "M218 " MSG_INVALID_EXTRUDER " "
-#define MSG_M221_INVALID_EXTRUDER           "M221 " MSG_INVALID_EXTRUDER " "
 #define MSG_ERR_NO_THERMISTORS              "No thermistors - no temperature"
 #define MSG_HEATING                         "Heating..."
 #define MSG_HEATING_COMPLETE                "Heating done."

Marlin/language.h

@@ -122,12 +122,6 @@
 #define MSG_END_FILE_LIST                   "End file list"
 #define MSG_INVALID_EXTRUDER                "Invalid extruder"
 #define MSG_INVALID_SOLENOID                "Invalid solenoid"
-#define MSG_M104_INVALID_EXTRUDER           "M104 " MSG_INVALID_EXTRUDER " "
-#define MSG_M105_INVALID_EXTRUDER           "M105 " MSG_INVALID_EXTRUDER " "
-#define MSG_M109_INVALID_EXTRUDER           "M109 " MSG_INVALID_EXTRUDER " "
-#define MSG_M200_INVALID_EXTRUDER           "M200 " MSG_INVALID_EXTRUDER " "
-#define MSG_M218_INVALID_EXTRUDER           "M218 " MSG_INVALID_EXTRUDER " "
-#define MSG_M221_INVALID_EXTRUDER           "M221 " MSG_INVALID_EXTRUDER " "
 #define MSG_ERR_NO_THERMISTORS              "No thermistors - no temperature"
 #define MSG_HEATING                         "Heating..."
 #define MSG_HEATING_COMPLETE                "Heating done."