Advanced key:layer checking in the validator

[RicoZ]

Recently I came across a bridge with layer=-1 across a river with (implicit) layer=0. Surprisingly Mapnik and many other renderers draw it "correctly" - bridge above water despite obviously wrong layer. The JOSM validator does not produce any warning in this situation.

This may serve as an example, version 5 of the way if someone fixes it:
​http://www.openstreetmap.org/way/28590490#map=19/45.86651/10.93736&layers=D

To detect this kind of error it could be necessary to model the vertical stacking by key:layer and compare that to the vertical stacking resulting from the algorithm described here:

​http://wiki.openstreetmap.org/wiki/Key:layer#Data_consumers

[RicoZ]

example error

[RicoZ]

attached example as I intend to fix the error in the OSM database soon.

While tweaking ​​http://wiki.openstreetmap.org/wiki/Key:layer#Data_consumers I came to the conclusion that a test for

(bridge!=no && layer<0 && location!=underground && indoor!=yes)

should be sufficient to catch this situation without false positives (or extremely few of them at worst).

[Klumbumbus]

In 8754/josm:

fix #11837 - add validator warning Suspicious tag/value combination: bridge|tunnel and layer<0|layer>0

[Klumbumbus]

In 8761/josm:

see #11837 - improve validator warning text