View source for CompatibilityBreakingChanges

This lists removed WML functionality and helpful hints for avoiding pitfalls.

The previous list is available [https://forums.wesnoth.org/viewtopic.php?t=58532 here].

== Compatibility breaking changes between 1.18 and 1.19/1.20 ==

=== Compatibility breaking (requires updates to work) ===

* '''[kill]''' now reduces target unit hitpoints to 0 before triggering '''last_breath, die''' events. This affects mentioned events that rely on [have_unit] conditions.
* WFL Removed properties '''unit.side''' and '''terrain.owner'''. Use '''unit.side_number''' and '''terrain.owner_side''' instead. They return 1-indexed side, removed properties returned 0-indexed side.
* Abilities with both '''add''' and '''sub''' now calculate value differently
* rotate_loc_around formula now works
* [era] with id=era_dunefolk does not exist anymore
* [side]'s leader attribute has been removed
* [side]'s [variables] tag is now used to set side variables. Use [side]'s [leader] tag to set a unit variable.
* Setting gold to decimal value fails with error. Previously it was converted to int automatically. As of 1.19.21, automatic conversion is only done in [gold], but not in Lua or [modify_side].
* The following macros were removed ([https://github.com/wesnoth/wesnoth/pull/11126 #11126])
** EARLY_FINISH_BONUS_NOTE
** NO_EARLY_FINISH_BONUS_NOTE
** NO_GOLD_CARRYOVER_NOTE
** NEW_GOLD_CARRYOVER_NOTE_100
** NEW_GOLD_CARRYOVER_NOTE_40
** NEW_GOLD_CARRYOVER_NOTE_20
** MISSILE_FRAME_FIREBALL
** MESSAGE
** STORY_PART_SPEECH
** LOYAL_UNDEAD_UNIT
** ON_SIGHTING
** MAKE_AI_SIDE_PERSISTENT
** DRAKE_FLYING_ANIM
** NO_INTERRUPT_NO_UNDO
** ENABLE_NIGHTBLADE
* Parsing of << in quotes has been fixed. This means cases like '''key="<<"''' do not error anymore and cases like '''key="<<" {MACRO} ">>"''' now expand the macro.
* Fire Guardian line images have been moved from units/monsters/ to units/monsters/fireghost/

=== Deprecations (will continue to work for now) ===
* rechange [experimental_filter_ability/active] and [experimental_filter_specials] to [filter_ability] and [filter_specials] and make "experimental_" deprecated.
* the default value of [drains] is deprecated and might be removed in 1.21, specify value=50 explicitly.
* u.abilities in lua and formula was renamed to u.ability_ids, u.abilities continues to work during 1.20

=== New features (help fill this list, https://wiki.wesnoth.org/Special:WhatLinksHere/Template:DevFeature1.19) ===
* StandardAbilityFilter, including [https://github.com/wesnoth/wesnoth/pull/7814 7814]
* [resistance] min_value
* [attack] alignment
* New events '''unit_hits''', '''unit_misses'''
* Positive '''attack_weight''' now affects weapon selection
* Unit attack [effect]+Lua+formula API min_range and max_range
* Lua unit attributes fearless and healthy
* wesnoth.game_config shows some color-related values
* wesnoth.units.rebuild
* stringx.ends_with, stringx.starts_with
* Unit formula new attributes objects, advancements_taken, traits_count, objects_count, advancements_taken_count, fearless, healthy
* Formula functions lerp_index, ends_with, replace_all, starts_with, get_palette
* Custom themes https://wiki.wesnoth.org/GUIToolkit#Custom_themes
* Abilities and specials now support [event] (does not work correctly due to [issue]10819[/issue])
* Ability & Weapon specials registry ([https://github.com/wesnoth/wesnoth/pull/10644 10644]) (does not work correctly if ability contains [event] due to [issue]10819[/issue])
* [effect][remove_specials]
* Expose unit pick dialog to Lua as a simple API call ([https://github.com/wesnoth/wesnoth/pull/8829 8829])
* [fire_event][data] can be accessed from other event as $data
* Unit Type Editor
* [era]auto_sort allows to use custom faction ordering
* [terrain_defaults] formula is now working as expected in case formula evaluates to null
* [set_menu_item] description substitutes variables when rightclick is used
* [defense]
* [resistance_defaults] is not causing OOS in random maps anymore
* Ability/weapon special descriptions support po variables in descriptions like '''$add''', '''$sub''' etc that contain the value of the relevant key. ([https://github.com/wesnoth/wesnoth/pull/10053 10053], [https://github.com/wesnoth/wesnoth/pull/10293 10293], [https://github.com/wesnoth/wesnoth/pull/10749 10749])
* Ability/weapon special help page ids now follow the format: '''ability_<unique_id>''' or '''weaponspecial_<unique_id>''' ([https://github.com/wesnoth/wesnoth/pull/11012 11012]).
* A lot more functions were added to https://wiki.wesnoth.org/LuaAPI/types/widget with https://wiki.wesnoth.org/index.php?title=LuaAPI%2Ftypes%2Fwidget&type=revision&diff=74843&oldid=74842