The old metatable was used as the metatable of the new element's
metatable, which doesn't make any sense at all.
Fixes#4079
(cherry picked from commit 56131f14c4)
This removes the Lua deprecation_message function in favour of exposing the C++ variant to Lua instead.
It also moves all deprecation messages to a separate logdomain, making them easily enabled en masse.
* Some improvements to the messages
* Don't clobber existing metatables on deprecated subtables
* Fix Lua deprecation messages not even being logged
* Fix deprecation of Lua subtables
* Don't clobber the metatable when deprecating a subtable
actual bugs found:
* backwards_compatibility.lua (undeclared global "helper")
* core.lua (use of undeclared global "helper")
* wml_tags.transform_unit had wrong code to deal with recall_cost
* wrong variable name in cave_map_generator
The implementation differs from already-existing
wml.variable.proxy in that it does not try to proxy table sub-fields,
and is fast & simple.
Example usage:
wml.variables.test = 123
print(wml.variables.test)
(as proposed by @DeFender1031)
All existing deprecation messages in the Lua code have been changed to
use the new deprecation system.
The goal is to eventually use an equivalent system for ALL areas of the API.
