Validator doesn't correctly diagnose/fix way with multiply-listed nodes

[AM909]

1. Go to the area ​http://www.openstreetmap.org/?lat=33.596117&lon=-117.789975&zoom=19 with Ctrl-G and download it.

2. Run the validator.

It will complain that the Newport Beach closed way is a "Self-intersecting way", but not correctly explain what the actual problem is. If you right-click and choose "Zoom to problem", you get a section of the way with 7 nodes. If you move them around, it seems that the way never crosses itself.

Looking at the underlying data, the problem is actually that 3 of the nodes are listed twice in the list of nodes. I'm assuming that it is normal for a closed way to have the first and last node the same (id 374701236), but the other two are apparently the problem (374624132 and 374707009). Because they immediately follow each other twice, moving them doesn't show the problem.

The validator should explain that this is the actual problem (the presence of the nodes more than once in the nodelist), and provide a means of fixing it.

[HamishB <hamish_b@…>]

see also #3715, #3720, #4445

[stoecker]

No longer reproducable. A duplicate nodeis a kind of self-intersection, so the warning is correct. If I remember right, the validator will also shown another error for this, where fix button can be used to solve the issue.

[AM909]

The attached .OSM demonstrates the problem. The way (-1408) goes along these nodes -1400, -1402, -1404, -1402, -1404, -1406. If you run the validator against it, it generates two warnings (Overlapping highways and Self-intersecting ways), but if you select either error in the validator dialog, the Fix button is not enabled and it does not provide any further detail about the problem.

It would be good if it gave you the IDs of the nodes at which it encountered the problem, like "Node -1402 is in way -1408 2 times" + "Node -1404 is in way -1408 2 times".

I do notice that there was a change in the rendering such that, if you look carefully, the portion of the way from -1402 to/from -1404 has a somewhat thicker and more jagged appearance than the others, which is somewhat helpful now that I know what to look for.

[simon04]

In 6574/josm:

fix #4959 - Validator: check and fix ways with duplicate way segments

For instance, a way with nodes 0 2 4 2 4 6 is fixed to 0 2 4 6.