[PATCH] IAE: Invalid number of points in LinearRing

[bagage]

What steps will reproduce the problem?

1. Open the bug.osm attached file. Select the way as reference layer
2. Use anything as subject layer
3. Hit "Generate matches"

What is the expected result?

Matches are generated.

What happens instead?

Exception is thrown "java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)".

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

Build-Date:2017-04-10 14:26:00
Revision:11883
Is-Local-Build:true

Identification: JOSM/1.5 (11883 SVN en) Linux Debian GNU/Linux 9.0 (stretch)
Memory Usage: 823 MB / 1760 MB (142 MB allocated, but free)
Java version: 1.8.0_121-8u121-b13-4-b13, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Java package: openjdk-8-jre:amd64-8u121-b13-4
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-13
Program arguments: [--language=en, ${HOME}/majcadastre/CL325-SAINT-RAMBERT-D ALBON/CL325-SAINT-RAMBERT-D ALBON-houses-simplifie.osm]
Dataset consistency test: No problems found

Plugins:
+ PicLayer (33148)
+ buildings_tools (33004)
+ conflation (0.5.3)
+ jts (32699)
+ rex (26)
+ todo (30000)
+ utilsplugin2 (33212)

Last errors/warnings:
- W: Old style SideButton usage for action org.openstreetmap.josm.plugins.todo.TodoDialog$MarkAction@4d2adbc0
- W: Old style SideButton usage for action org.openstreetmap.josm.plugins.todo.TodoDialog$MarkSelectedAction@383a536
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
- E: Handled by bug report queue: java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)


=== REPORTED CRASH DATA ===
BugReportExceptionHandler#handleException:
No data collected.

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: AWT-EventQueue-0 (17) of main
java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
	at com.vividsolutions.jts.geom.LinearRing.validateConstruction(LinearRing.java:114)
	at com.vividsolutions.jts.geom.LinearRing.<init>(LinearRing.java:106)
	at org.openstreetmap.josm.plugins.jts.JTSConverter.convertWay(JTSConverter.java:93)
	at org.openstreetmap.josm.plugins.jts.JTSConverter.convert(JTSConverter.java:104)
	at org.openstreetmap.josm.plugins.conflation.OsmFeature.<init>(OsmFeature.java:35)
	at org.openstreetmap.josm.plugins.conflation.MatchesComputation.createFeatureCollection(MatchesComputation.java:119)
	at org.openstreetmap.josm.plugins.conflation.MatchesComputation.generateMatches(MatchesComputation.java:48)
	at org.openstreetmap.josm.plugins.conflation.ConflationToggleDialog$2.realRun(ConflationToggleDialog.java:1142)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.doRealRun(PleaseWaitRunnable.java:95)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.run(PleaseWaitRunnable.java:143)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

[bagage]

the bogus item that raises the exception

[bagage]

patch

[bagage]

I've added a patch to stop the IAE - and in my case for conflation it works great (eg as expected).

[GerdP]

I'd rather say that a way with only 2 distinct nodes is not closed. Or maybe the check should be changed to Way.isArea()
which seems to catch also duplicated notes.

[bagage]

I'm not sure I can argue much here about the better approach. Indeed 2-nodes way should not be considered closed IMO but I do not know side effects it may have. I believe you are in a better position to know the best fix here :-).