Destinations ignored on two-way roads

[1ec5]

OSRM ignores destination tags on ways that are tagged oneway=no or that lack a oneway tag. For example, @abhisheksaikia found that this way appears without a destination in this route despite having destination:backward and destination:ref:backward tags.

The cause is that the following code calls get_destination() only if the road is a one-way road:

osrm-backend/profiles/lib/way_handlers.lua

Lines 103 to 109 in 979ec7f

	-- handle destination tags
	function WayHandlers.destinations(profile,way,result,data)
	if data.is_forward_oneway or data.is_reverse_oneway then
	local destination = get_destination(way, data.is_forward_oneway)
	result.destinations = canonicalizeStringList(destination, ",")
	end
	end

This code originally lived in the one-way handler:

osrm-backend/profiles/car.lua

Lines 637 to 645 in 0fbd18b

	function handle_oneway(way,result)
	local oneway = way:get_value_by_key("oneway")
	if obey_oneway then
	if oneway == "-1" then
	result.forward_mode = mode.inaccessible
	local is_forward = false
	local destination = get_destination(way, is_forward)
	result.destinations = canonicalizeStringList(destination, ",")

It looks like this behavior was introduced intentionally in c7e1939 for #2328 to work around tagging mistakes like using destination instead of destination:forward on a two-way road. While mappers can still be prone to that kind of mistake, it’s better to rely on linters to catch these issues. Also, #3061 implemented support for destination:forward and destination:backward in the meantime.

/cc @ghoshkaj @daniel-j-h

[1ec5]

228 two-way ways are tagged with destination, destination:ref, or destination:street in the contiguous U.S. and vicinity. The number of steps affected in OSRM output is probably lower, since a ramp instruction only includes the destination of the link way that touches the maneuver point. Also, this query includes motorways with implied oneway tags, which OSRM probably handles correctly already.

[daniel-j-h]

See #4590. We store destinations without forward/backward split here:

osrm-backend/include/extractor/extraction_way.hpp

Line 110 in 979ec7f

std::string destinations;

same for name, pronunciation, etc.

We need to properly split these first, pull through the pipeline. Then expose them to the Lua profiles.

[1ec5]

Also related: #4544.