id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
20451	Warn about supermassive avoidable multipolygons (landuse=farmland for start)	mkoniecz	team	"==== What steps will reproduce the problem?
1. Download https://www.openstreetmap.org/relation/10953749 (multipolygon `landuse=farmland` constructed from 933 ways, around 68 000 nodes in total). 
2. Run validator

==== What is the expected result?
Validator complains about this supermassive multipolygon that has no reason to exist.

==== What happens instead?
Nothing.

==== Please provide any additional information below. Attach a screenshot if possible.

Warning should not be emitted for named landuses, where supermassive multipolygons would be justifiable.

I already notified https://wiki.openstreetmap.org/wiki/Unite_Maps_Initiative/UN_Mappers about issues with their mapping (see https://wiki.openstreetmap.org/wiki/Mechanical_Edits/Mateusz_Konieczny/deimport_landuse_in_central_Africa,_mostly_East_Congo ) and I got reply via email.

They claim that it is not import, but manual tracing from imagery.

Warning from JOSM would help in such case to provide early feedback that they are making a mistake.

BTW, is there any sane way to split that monster into smaller parts? My typical methods ""remove some ways multipolygon, add it to another new one"" or ""delete multipolygon, construct new areas from its ways"" would be horrific here.
{{{
Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2021-01-21 23:33:21 +0100 (Thu, 21 Jan 2021)
Revision:17474
Build-Date:2021-01-22 02:30:49
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (17474 en) Linux Ubuntu 20.04.2 LTS
Memory Usage: 660 MB / 3974 MB (405 MB allocated, but free)
Java version: 11.0.9.1+1-Ubuntu-0ubuntu1.20.04, Ubuntu, OpenJDK 64-Bit Server VM
Look and Feel: javax.swing.plaf.metal.MetalLookAndFeel
Screen: :0.0 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→16×16, 32×32→32×32
Desktop environment: LXQt
Java package: openjdk-11-jre:amd64-11.0.9.1+1-0ubuntu1~20.04
Java ATK Wrapper package: libatk-wrapper-java:all-0.37.1-1
Environment variable LANG: en_US.UTF-8
libcommons-logging-java: libcommons-logging-java:all-1.2-2
fonts-noto: fonts-noto:-
Dataset consistency test: No problems found

Plugins:
+ buildings_tools (35669)
+ reverter (35688)
+ todo (30306)

Validator rules:
+ https://josm.openstreetmap.de/josmfile?page=Rules/OSMLint&zip=1
+ ${HOME}/Documents/install_moje/OSM software/manual editing and discussions/josm/resources/data/validator/deprecated.mapcss
}}}
"	enhancement	new	normal		Core validator			template_report