id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
19312	detect circular dependencies in relations	GerdP	GerdP	"The shortest possible loop is a relation that contains itself as a member. Bigger loops may be formed when a relation A contains relation B as member and B contains A. Or a seqeance like A-B-C-D-A.
I don't think that there is any situation where this makes sense, so this should be flagged as an error.
Of, JOSM can only detect the loops when the corresponding relations are loaded.
I coded this test to find a loop in type=waterway relations and thought it might be useful.
Two new messages are produced:
`Relation contains itself as a member` 
or for the complexer cases:
`Relations build a dependency loop`
I think the first is clear, the 2nd might be improved. Possible alternative:
`Relations build a parent/child dependency loop`

For the simple case we can offer an autofix, for the complex case this needs expert knowledge.
"	enhancement	closed	normal	20.06	Core validator		fixed