id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
20130	[Patch] Use mapcss rules instead of CrossingWays java code to find overlapping areas	GerdP	GerdP	"Today we use the java code in `CrossingWays` to find e.g. ""Crossing building/residential area"".
This should better be done using a rule like this
{{{
#!mapcss
/* Building overlapping landuse residential (spatial test) */
area[building][building!~/no|entrance/] ⧉ area[landuse=residential]{
  throwWarning: tr(""Overlapping buildings/residential area"");
}
}}}

Reasoning: 
- it also handles multipolygons (if they are complete)
- ~~it marks the overlapping area, not the crossing segments~~ in fact this is a contra argument
- it also handles overlaps where the two areas share nodes

In !r17084 `CrossingWays` also finds crossings between 
- building/waterway=riverbank (""Crossing building/waterway"")
- building/railway=platform (""Crossing building/railway"" (false positive?)
It doesn't find other crossing like those between building/natural=water, see #20121

Maybe it is possible to create a single mapcss test to catch different types of areas which shouldn't overlap a building?

I didn't test the impact on performance, I assume it is rather small."	enhancement	assigned	normal		Core validator			crossing	Klumbumbus simon04