`hand` items use their `on_use` function

[tigersharke]

Luanti version

commit that caused the breakage: https://github.com/luanti-org/luanti/pull/15743

Luanti 5.12.0-dev (BSD)
Using LuaJIT 2.1.1736781742
Built by Clang 19.1
Running on FreeBSD/14.2 amd64
BUILD_TYPE=Release
RUN_IN_PLACE=0
USE_CURL=1
USE_GETTEXT=1
USE_SOUND=1
STATIC_SHAREDIR="/usr/local/share/luanti"
STATIC_LOCALEDIR="/usr/local/share/locale"

Operating system and version

FreeBSD/14.2 amd64

CPU model

No response

GPU model

No response

Active renderer

No response

Summary

When attempting to play on a NodeCore server or NodeCore in singleplayer, the usual action for left mouse click is ineffectual. There is animation for hand movement but no objects can be broken (dirt, leaves) or taken (flowers, any item on ground). If there is already a tool in hand, it may be used but if dropped or placed then it cannot be reclaimed.

This specifically affects NodeCore but could affect more.

Steps to reproduce

Build or install commit 15743, run luanti client to use a NodeCore server or NodeCore in singleplayer, attempt to break leaves from a tree or yank a flower, or break plain dirt to loose dirt, all use the left click of mouse for action.

[cx384]

Can confirm, e037873 is the first bad commit.
I'm not sure if this is an engine bug or if NodeCore is relying on undefined/undocumented behavior, since it works fine in MTG. Need to investigate.

[cx384]

Found the problem.
The hand in NodeCore has an on_use definition, which means on left click instead of digging, the on_use is called.
https://gitlab.com/sztest/nodecore/-/blob/master/mods/nc_player_hand/hand.lua?ref_type=heads#L35

Before #15743 this function could not have been executed anyway (except if you actually get the hand as an item), so I consider this NodeCore's fault.

We could easily fix this by ignoring on_use for hand items, but I suppose we don't want to do this.

[sfan5]

Yeah sounds like game issue.

[appgurueu]

related: luanti-org/docs.luanti.org#214

(we should remember to mention this in compatibility notes, similar to the bone thing.)