Strange behavior when dragging&dropping from MTG creative inventory (since #13146)

[grorp]

Minetest version

Probably all versions since 252c79d (#13146)

Minetest 5.8.0-dev-252c79d53a (Linux)
Using Irrlicht 1.9.0mt11
Using LuaJIT 2.1.0-beta3
BUILD_TYPE=RelWithDebInfo
RUN_IN_PLACE=1
USE_CURL=1
USE_GETTEXT=1
USE_SOUND=1
STATIC_SHAREDIR="."
STATIC_LOCALEDIR="locale"

OS / Hardware

Operating system: Fedora Linux 37 (Workstation Edition)

Summary

I found the following issue that might be worth having a look into:

1. Use the MTG infinite source creative inventory
2. Drag & drop an ItemStack from the creative inventory onto another ItemStack of identical types
3. The ItemStack count combines but the dragged ItemStack is not released
4. When tapping again into any other empty or ItemStack of identical types, another copy is taken from the creative inventory.
   Expected: release the dragged ItemStack when releasing the finger press.

Originally posted by @SmallJoker in #13872 (comment)

This happens on desktop as well and seems to be a regression from 252c79d.

Video of the problem (252c79d)

Also notice that the size of the held itemstack increases beyond the maximum stack size when I move over multiple slots while dragging&dropping.

strange.creative.inventory.behavior.mp4

Video of the correct behavior (23f7aab)

correct.creative.inventory.behavior.mp4

Steps to reproduce

See the quote from SmallJoker above.

[rubenwardy]

Is anyone working on this / any progress?

[grorp]

Hey @OgelGames, any chance you could take a look at this?

[sfence]

Look like a server-side reaction to client code

minetest/src/gui/guiFormSpecMenu.cpp

Lines 4818 to 4829 in 6303334

	m_selected_amount += pickup_amount;
	infostream << "Handing IAction::Move to manager" << std::endl;
	IMoveAction *a = new IMoveAction();
	a->count = pickup_amount;
	a->from_inv = s.inventoryloc;
	a->from_list = s.listname;
	a->from_i = s.i;
	a->to_inv = m_selected_item->inventoryloc;
	a->to_list = m_selected_item->listname;
	a->to_i = m_selected_item->i;
	m_invmgr->inventoryAction(a);

where is not expected that the server can completely disallow move based on Lua callback return values:

INFO[Server]: IMoveAction::apply(): move was completely disallowed: move_count=3 from inv="player:singleplayer" list="main" i=3 to inv="detached:creative_singleplayer" list="main" i=27

minetest/src/inventorymanager.cpp

Lines 457 to 477 in 6303334

	/* If no items will be moved, don't go further */
	if (move_count == 0) {
	// Undo client prediction. See 'clientApply'
	if (from_inv.type == InventoryLocation::PLAYER)
	list_from->setModified();
	if (to_inv.type == InventoryLocation::PLAYER)
	list_to->setModified();
	infostream<<"IMoveAction::apply(): move was completely disallowed:"
	<<" move_count="<<old_move_count
	<<" from inv=\""<<from_inv.dump()<<"\""
	<<" list=\""<<from_list<<"\""
	<<" i="<<from_i
	<<" to inv=\""<<to_inv.dump()<<"\""
	<<" list=\""<<to_list<<"\""
	<<" i="<<to_i
	<<std::endl;
	return;
	}