deprecate use-lane -- the information can be found in the intersections array

include/engine/api/route_api.hpp

@@ -174,14 +174,13 @@ class RouteAPI : public BaseAPI
                 guidance::trimShortSegments(steps, leg_geometry);
                 leg.steps = guidance::postProcess(std::move(steps));
                 leg.steps = guidance::collapseTurnInstructions(std::move(leg.steps));
+                leg.steps = guidance::anticipateLaneChange(std::move(leg.steps));
                 leg.steps = guidance::buildIntersections(std::move(leg.steps));
                 leg.steps = guidance::suppressShortNameSegments(std::move(leg.steps));
                 leg.steps = guidance::assignRelativeLocations(std::move(leg.steps),
                                                               leg_geometry,
                                                               phantoms.source_phantom,
                                                               phantoms.target_phantom);
-                leg.steps = guidance::anticipateLaneChange(std::move(leg.steps));
-                leg.steps = guidance::collapseUseLane(std::move(leg.steps));
                 leg_geometry = guidance::resyncGeometry(std::move(leg_geometry), leg.steps);
             }
 

include/engine/guidance/verbosity_reduction.hpp

@@ -20,16 +20,6 @@ namespace guidance
 OSRM_ATTR_WARN_UNUSED
 std::vector<RouteStep> suppressShortNameSegments(std::vector<RouteStep> steps);
 
-// remove use lane information that is not actually a turn. For post-processing, we need to
-// associate lanes with every turn. Some of these use-lane instructions are not required after lane
-// anticipation anymore. This function removes all use lane instructions that are not actually used
-// anymore since all lanes going straight are used anyhow.
-// FIXME this is currently only a heuristic. We need knowledge on which lanes actually might become
-// turn lanes. If a straight lane becomes a turn lane, this might be something to consider. Right
-// now we bet on lane-anticipation to catch this.
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> collapseUseLane(std::vector<RouteStep> steps);
-
 } // namespace guidance
 } // namespace engine
 } // namespace osrm

include/extractor/guidance/turn_instruction.hpp

@@ -207,7 +207,9 @@ inline bool isSilent(const extractor::guidance::TurnInstruction instruction)
 {
     return instruction.type == extractor::guidance::TurnType::NoTurn ||
            instruction.type == extractor::guidance::TurnType::Suppressed ||
-           instruction.type == extractor::guidance::TurnType::StayOnRoundabout;
+           instruction.type == extractor::guidance::TurnType::StayOnRoundabout ||
+           // it is enough to output them within the intersections array
+           instruction.type == extractor::guidance::TurnType::UseLane;
 }
 
 inline bool hasRampType(const extractor::guidance::TurnInstruction instruction)