use std::nullopt

src/guidance/intersection_handler.cpp

@@ -450,7 +450,7 @@ IntersectionHandler::getNextIntersection(const NodeID at, const EdgeID via) cons
     if (intersection_parameters.node == SPECIAL_NODEID ||
         intersection_parameters.edge == SPECIAL_EDGEID)
     {
-        return {};
+        return std::nullopt;
     }
 
     auto intersection = extractor::intersection::getConnectedRoads<false>(node_based_graph,
@@ -465,7 +465,7 @@ IntersectionHandler::getNextIntersection(const NodeID at, const EdgeID via) cons
 
     if (intersection.size() <= 2 || intersection.isTrafficSignalOrBarrier())
     {
-        return {};
+        return std::nullopt;
     }
 
     return std::make_optional(IntersectionViewAndNode{std::move(intersection), intersection_node});

src/guidance/sliproad_handler.cpp

@@ -652,7 +652,7 @@ std::optional<std::size_t> SliproadHandler::getObviousIndexWithSliproads(
     // then the non-Sliproad is the obvious one.
     if (intersection.size() != 3)
     {
-        return {};
+        return std::nullopt;
     }
 
     const auto forking = intersection[1].instruction.type == TurnType::Fork &&
@@ -660,7 +660,7 @@ std::optional<std::size_t> SliproadHandler::getObviousIndexWithSliproads(
 
     if (!forking)
     {
-        return {};
+        return std::nullopt;
     }
 
     const auto first = getNextIntersection(at, intersection.getRightmostRoad().eid);
@@ -668,12 +668,12 @@ std::optional<std::size_t> SliproadHandler::getObviousIndexWithSliproads(
 
     if (!first || !second)
     {
-        return {};
+        return std::nullopt;
     }
 
     if (first->intersection.isDeadEnd() || second->intersection.isDeadEnd())
     {
-        return {};
+        return std::nullopt;
     }
 
     // In case of loops at the end of the road, we will arrive back at the intersection
@@ -688,7 +688,7 @@ std::optional<std::size_t> SliproadHandler::getObviousIndexWithSliproads(
         return std::make_optional(std::size_t{1});
     }
 
-    return {};
+    return std::nullopt;
 }
 
 bool SliproadHandler::nextIntersectionIsTooFarAway(const NodeID start, const EdgeID onto) const

src/guidance/turn_handler.cpp

@@ -647,7 +647,7 @@ TurnHandler::findForkCandidatesByGeometry(Intersection &intersection) const
             }
         }
     }
-    return {};
+    return std::nullopt;
 }
 
 // check if the fork candidates (all roads between left and right) and the
@@ -740,7 +740,7 @@ std::optional<TurnHandler::Fork> TurnHandler::findFork(const EdgeID via_edge,
         }
     }
 
-    return {};
+    return std::nullopt;
 }
 
 void TurnHandler::handleDistinctConflict(const EdgeID via_edge,

src/util/coordinate_calculation.cpp

@@ -181,7 +181,7 @@ circleCenter(const Coordinate C1, const Coordinate C2, const Coordinate C3)
     // require three distinct points
     if (C1 == C2 || C2 == C3 || C1 == C3)
     {
-        return {};
+        return std::nullopt;
     }
 
     // define line through c1, c2 and c2,c3
@@ -196,7 +196,7 @@ circleCenter(const Coordinate C1, const Coordinate C2, const Coordinate C3)
         (std::abs(C2C1_lat) < std::numeric_limits<double>::epsilon() &&
          std::abs(C3C2_lat) < std::numeric_limits<double>::epsilon()))
     {
-        return {};
+        return std::nullopt;
     }
     else if (std::abs(C2C1_lon) < std::numeric_limits<double>::epsilon())
     {
@@ -234,7 +234,7 @@ circleCenter(const Coordinate C1, const Coordinate C2, const Coordinate C3)
 
         // can this ever happen?
         if (std::abs(C2C1_slope - C3C2_slope) < std::numeric_limits<double>::epsilon())
-            return {};
+            return std::nullopt;
 
         const double C1_y = static_cast<double>(toFloating(C1.lat));
         const double C1_x = static_cast<double>(toFloating(C1.lon));
@@ -248,7 +248,7 @@ circleCenter(const Coordinate C1, const Coordinate C2, const Coordinate C3)
                            (2 * (C3C2_slope - C2C1_slope));
         const double lat = (0.5 * (C1_x + C2_x) - lon) / C2C1_slope + 0.5 * (C1_y + C2_y);
         if (lon < -180.0 || lon > 180.0 || lat < -90.0 || lat > 90.0)
-            return {};
+            return std::nullopt;
         else
             return Coordinate(FloatLongitude{lon}, FloatLatitude{lat});
     }

src/util/timezones.cpp

@@ -168,6 +168,6 @@ std::optional<struct tm> Timezoner::operator()(const point_t &point) const
         if (boost::geometry::within(point, local_times[index].first))
             return local_times[index].second;
     }
-    return {};
+    return std::nullopt;
 }
 } // namespace osrm::updater