Move extruder-specific DC settings

CURA-4708

Read code comments.

cura/Settings/ExtruderStack.py

@@ -8,6 +8,7 @@ from UM.MimeTypeDatabase import MimeType, MimeTypeDatabase
 from UM.Settings.ContainerStack import ContainerStack
 from UM.Settings.ContainerRegistry import ContainerRegistry
 from UM.Settings.Interfaces import ContainerInterface, PropertyEvaluationContext
+from UM.Settings.SettingInstance import SettingInstance
 
 from . import Exceptions
 from .CuraContainerStack import CuraContainerStack
@@ -16,6 +17,11 @@ from .ExtruderManager import ExtruderManager
 if TYPE_CHECKING:
     from cura.Settings.GlobalStack import GlobalStack
 
+
+_EXTRUDER_SPECIFIC_DEFINITION_CHANGES_SETTINGS = ["machine_nozzle_size",
+                                                  "material_diameter"]
+
+
 ##  Represents an Extruder and its related containers.
 #
 #
@@ -39,6 +45,29 @@ class ExtruderStack(CuraContainerStack):
         # For backward compatibility: Register the extruder with the Extruder Manager
         ExtruderManager.getInstance().registerExtruder(self, stack.id)
 
+        # Now each machine will have at least one extruder stack. If this is the first extruder, the extruder-specific
+        # settings such as nozzle size and material diameter should be moved from the machine's definition_changes to
+        # the this extruder's definition_changes.
+        #
+        # We do this here because it is tooooo expansive to do it in the version upgrade: During the version upgrade,
+        # when we are upgrading a definition_changes container file, there is NO guarantee that other files such as
+        # machine an extruder stack files are upgraded before this, so we cannot read those files assuming they are in
+        # the latest format.
+        if self.getMetaDataEntry("position") == "0":
+            for key in _EXTRUDER_SPECIFIC_DEFINITION_CHANGES_SETTINGS:
+                setting_value = stack.definitionChanges.getProperty(key, "value")
+                if setting_value is None:
+                    continue
+
+                setting_definition = stack.getSettingDefinition(key)
+                new_instance = SettingInstance(setting_definition, self.definitionChanges)
+                new_instance.setProperty("value", setting_value)
+                new_instance.resetState()  # Ensure that the state is not seen as a user state.
+                self.definitionChanges.addInstance(new_instance)
+                self.definitionChanges.setDirty(True)
+
+                stack.definitionChanges.removeInstance(key, postpone_emit = True)
+
     @override(ContainerStack)
     def getNextStack(self) -> Optional["GlobalStack"]:
         return super().getNextStack()