get_connected_players wrongly returns empty list in register_on_shutdown

[appgurueu]

Minetest version

Reported by BluebirdGrey51 on IRC on version 5.9.0-dev-87232358d. I can also reproduce this.

Summary

get_connected_players wrongly returns an empty list in register_on_shutdown - 5.8.0 returned a list containing the connected players, as it should. There isn't even a good way for modders to work around this since register_on_leaveplayer doesn't get run on shutdown. Hence, if modders want to do something with players on shutdown (in BluebirdGrey51's example, setting some metadata values), they need this to work.

Steps to reproduce

minetest.register_on_shutdown(function()
	print("# connected players", #minetest.get_connected_players())
end)

On 5.8.0: Start singleplayer game. Exit to OS. Output on terminal: # connected players 1.

Now do the same on 5.9-dev. Output: # connected players 0.

[appgurueu]

Possible culprits (not tested yet): e7dbd32 and 32f68f3. @SmallJoker

[wsor4035]

related #14711

[sfan5]

Needless to say we should add some test code to devtest for these cases.

[SmallJoker]

Since ef0009a, the disconnected players are now unloaded properly explicitly before ServerEnvironment destruction. Hence these objects no longer appeared in get_connected_players because they are (and already in were in 5.8.0) - in fact - already disconnected at this point.

EDIT:

get_connected_players wrongly returns an empty list in register_on_shutdown - 5.8.0 returned a list containing the connected players, as it should.

This behaviour is not documented. Intuitively it would however indeed make sense to me to still have the player list available there - even if they're already gone.

[appgurueu]

This behaviour is not documented.

Indeed we should document it.

Intuitively it would however indeed make sense to me to still have the player list available there - even if they're already gone.

It's not just intuition. It's pretty much a necessity if you want to do any player-related things on shutdown, such as persisting data to player meta, since register_on_leaveplayer doesn't run on shutdown.