Auto-update properties when replacing a node

[ajreckof]

Fixes #78299

The idea is to do something similar to what is done for auto updating NodePath

[Calinou]

With this PR, changing the node type from Node2D to Node does nothing – the node remains a Node2D.

Attempting to change from Node2D to Node3D prints:

  ./scene/main/node.cpp:1992 - Parameter "common_parent" is null.

While the latter case isn't expected to work, it should print an human-readable error message.

PS: I removed the cherrypick:4.0 label as I can't reproduce this on 4.0.3: #78299 (comment)

[ajreckof]

With this PR, changing the node type from Node2D to Node does nothing – the node remains a Node2D.

I can't reproduce locally. Did you check by removing the script because right now changing the type of a node that has a script feels like it is not working because icon does not change because the node still inherit the last type and the script now dictates the icon even without @icon. I don't know if there is an issue tracking this.

Attempting to change from Node2D to Node3D prints:

  ./scene/main/node.cpp:1992 - Parameter "common_parent" is null.

While the latter case isn't expected to work, it should print an human-readable error message.

I agree with you it should print a better error. I remember thinking about it but I didn't know what to do about it. I'm wondering maybe just removing the reference ?
Just for reference before this PR this was already a problem because the node would have still pointed to a Node that did not correspond to the filter.

Edit : I was able to reproduce the error but then it disappeared. There is something strange on how it appears :(.

[Calinou]

Tested locally (rebased on top of master dcd187d), it works as expected. The node type changes correctly and the exported variable reference is kept.

Code looks good to me at a glance.

[YuriSizov]

Thanks!