Replace GCC-specific attribute with [[nodiscard]] attribute (#6899)

Author: DennisOSRM

include/engine/guidance/collapse_turns.hpp

@@ -1,7 +1,6 @@
 #ifndef OSRM_ENGINE_GUIDANCE_COLLAPSE_HPP
 
 #include "engine/guidance/route_step.hpp"
-#include "util/attributes.hpp"
 
 #include <type_traits>
 #include <vector>
@@ -12,16 +11,15 @@ namespace osrm::engine::guidance
 // Multiple possible reasons can result in unnecessary/confusing instructions
 // Collapsing such turns into a single turn instruction, we give a clearer
 // set of instructions that is not cluttered by unnecessary turns/name changes.
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> collapseTurnInstructions(std::vector<RouteStep> steps);
+[[nodiscard]] std::vector<RouteStep> collapseTurnInstructions(std::vector<RouteStep> steps);
 
 // Multiple possible reasons can result in unnecessary/confusing instructions
 // A prime example would be a segregated intersection. Turning around at this
 // intersection would result in two instructions to turn left.
 // Collapsing such turns into a single turn instruction, we give a clearer
 // set of instructions that is not cluttered by unnecessary turns/name changes.
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> collapseSegregatedTurnInstructions(std::vector<RouteStep> steps);
+[[nodiscard]] std::vector<RouteStep>
+collapseSegregatedTurnInstructions(std::vector<RouteStep> steps);
 
 // A combined turn is a set of two instructions that actually form a single turn, as far as we
 // perceive it. A u-turn consisting of two left turns is one such example. But there are also lots

include/engine/guidance/collapsing_utility.hpp

@@ -3,7 +3,6 @@
 
 #include "guidance/turn_instruction.hpp"
 #include "engine/guidance/route_step.hpp"
-#include "util/attributes.hpp"
 #include "util/bearing.hpp"
 #include "util/guidance/name_announcements.hpp"
 
@@ -166,8 +165,7 @@ inline bool areSameSide(const RouteStep &lhs, const RouteStep &rhs)
 }
 
 // do this after invalidating any steps to compress the step array again
-OSRM_ATTR_WARN_UNUSED
-inline std::vector<RouteStep> removeNoTurnInstructions(std::vector<RouteStep> steps)
+[[nodiscard]] inline std::vector<RouteStep> removeNoTurnInstructions(std::vector<RouteStep> steps)
 {
     // finally clean up the post-processed instructions.
     // Remove all invalid instructions from the set of instructions.

include/engine/guidance/lane_processing.hpp

@@ -1,10 +1,9 @@
 #ifndef OSRM_ENGINE_GUIDANCE_LANE_PROCESSING_HPP_
 #define OSRM_ENGINE_GUIDANCE_LANE_PROCESSING_HPP_
 
-#include <vector>
-
 #include "engine/guidance/route_step.hpp"
-#include "util/attributes.hpp"
+
+#include <vector>
 
 namespace osrm::engine::guidance
 {
@@ -14,9 +13,9 @@ namespace osrm::engine::guidance
 // we anticipate lane changes emitting only matching lanes early on.
 // the second parameter describes the duration that we feel two segments need to be apart to count
 // as separate maneuvers.
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> anticipateLaneChange(std::vector<RouteStep> steps,
-                                            const double min_distance_needed_for_lane_change = 200);
+[[nodiscard]] std::vector<RouteStep>
+anticipateLaneChange(std::vector<RouteStep> steps,
+                     const double min_distance_needed_for_lane_change = 200);
 
 } // namespace osrm::engine::guidance
 

include/engine/guidance/post_processing.hpp

@@ -5,16 +5,14 @@
 #include "engine/guidance/leg_geometry.hpp"
 #include "engine/guidance/route_step.hpp"
 #include "engine/phantom_node.hpp"
-#include "util/attributes.hpp"
 
 #include <vector>
 
 namespace osrm::engine::guidance
 {
 
 // passed as none-reference to modify in-place and move out again
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> handleRoundabouts(std::vector<RouteStep> steps);
+[[nodiscard]] std::vector<RouteStep> handleRoundabouts(std::vector<RouteStep> steps);
 
 // trim initial/final segment of very short length.
 // This function uses in/out parameter passing to modify both steps and geometry in place.
@@ -24,23 +22,21 @@ std::vector<RouteStep> handleRoundabouts(std::vector<RouteStep> steps);
 void trimShortSegments(std::vector<RouteStep> &steps, LegGeometry &geometry);
 
 // assign relative locations to depart/arrive instructions
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> assignRelativeLocations(std::vector<RouteStep> steps,
-                                               const LegGeometry &geometry,
-                                               const PhantomNode &source_node,
-                                               const PhantomNode &target_node);
+[[nodiscard]] std::vector<RouteStep> assignRelativeLocations(std::vector<RouteStep> steps,
+                                                             const LegGeometry &geometry,
+                                                             const PhantomNode &source_node,
+                                                             const PhantomNode &target_node);
 
 // collapse suppressed instructions remaining into intersections array
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> buildIntersections(std::vector<RouteStep> steps);
+[[nodiscard]] std::vector<RouteStep> buildIntersections(std::vector<RouteStep> steps);
 
 // postProcess will break the connection between the leg geometry
 // for which a segment is supposed to represent exactly the coordinates
 // between routing maneuvers and the route steps itself.
 // If required, we can get both in sync again using this function.
 // Move in LegGeometry for modification in place.
-OSRM_ATTR_WARN_UNUSED
-LegGeometry resyncGeometry(LegGeometry leg_geometry, const std::vector<RouteStep> &steps);
+[[nodiscard]] LegGeometry resyncGeometry(LegGeometry leg_geometry,
+                                         const std::vector<RouteStep> &steps);
 
 /**
  * Apply maneuver override relations to the selected route.

include/engine/guidance/verbosity_reduction.hpp

@@ -2,7 +2,6 @@
 #define OSRM_ENGINE_GUIDANCE_VERBOSITY_REDUCTION_HPP_
 
 #include "engine/guidance/route_step.hpp"
-#include "util/attributes.hpp"
 
 #include <vector>
 
@@ -13,8 +12,7 @@ namespace osrm::engine::guidance
 // to announce them. All these that are not collapsed into a single turn (think segregated
 // intersection) have to be checked for the length they are active in. If they are active for a
 // short distance only, we don't announce them
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> suppressShortNameSegments(std::vector<RouteStep> steps);
+[[nodiscard]] std::vector<RouteStep> suppressShortNameSegments(std::vector<RouteStep> steps);
 
 } // namespace osrm::engine::guidance
 

include/extractor/intersection/coordinate_extractor.hpp

@@ -1,16 +1,15 @@
 #ifndef OSRM_EXTRACTOR_INTERSECTION_COORDINATE_EXTRACTOR_HPP_
 #define OSRM_EXTRACTOR_INTERSECTION_COORDINATE_EXTRACTOR_HPP_
 
-#include <utility>
-#include <vector>
-
 #include "extractor/compressed_edge_container.hpp"
 #include "extractor/query_node.hpp"
 
-#include "util/attributes.hpp"
 #include "util/coordinate.hpp"
 #include "util/node_based_graph.hpp"
 
+#include <utility>
+#include <vector>
+
 namespace osrm::extractor::intersection
 {
 
@@ -27,17 +26,16 @@ class CoordinateExtractor
      * Note: The segment between intersection and turn coordinate can be zero, if the OSM modelling
      * is unfortunate. See https://github.com/Project-OSRM/osrm-backend/issues/3470
      */
-    OSRM_ATTR_WARN_UNUSED
-    util::Coordinate GetCoordinateAlongRoad(const NodeID intersection_node,
-                                            const EdgeID turn_edge,
-                                            const bool traversed_in_reverse,
-                                            const NodeID to_node,
-                                            const std::uint8_t number_of_in_lanes) const;
+    [[nodiscard]] util::Coordinate
+    GetCoordinateAlongRoad(const NodeID intersection_node,
+                           const EdgeID turn_edge,
+                           const bool traversed_in_reverse,
+                           const NodeID to_node,
+                           const std::uint8_t number_of_in_lanes) const;
 
     // Given a set of precomputed coordinates, select the representative coordinate along the road
     // that best describes the turn
-    OSRM_ATTR_WARN_UNUSED
-    util::Coordinate
+    [[nodiscard]] util::Coordinate
     ExtractRepresentativeCoordinate(const NodeID intersection_node,
                                     const EdgeID turn_edge,
                                     const bool traversed_in_reverse,
@@ -47,28 +45,26 @@ class CoordinateExtractor
 
     // instead of finding only a single coordinate, we can also list all coordinates along a
     // road.
-    OSRM_ATTR_WARN_UNUSED std::vector<util::Coordinate>
+    [[nodiscard]] std::vector<util::Coordinate>
     GetCoordinatesAlongRoad(const NodeID intersection_node,
                             const EdgeID turn_edge,
                             const bool traversed_in_reverse,
                             const NodeID to_node) const;
 
     // wrapper in case of normal forward edges (traversed_in_reverse = false, to_node =
     // node_based_graph.GetTarget(turn_edge)
-    OSRM_ATTR_WARN_UNUSED
-    std::vector<util::Coordinate> GetForwardCoordinatesAlongRoad(const NodeID from,
-                                                                 const EdgeID turn_edge) const;
+    [[nodiscard]] std::vector<util::Coordinate>
+    GetForwardCoordinatesAlongRoad(const NodeID from, const EdgeID turn_edge) const;
 
     // a less precise way to compute coordinates along a route. Due to the heavy interaction of
     // graph traversal and turn instructions, we often don't care for high precision. We only want
     // to check for available connections in order, or find (with room for error) the straightmost
     // turn. This function will offer a bit more error potential but allow for much higher
     // performance
-    OSRM_ATTR_WARN_UNUSED
-    util::Coordinate GetCoordinateCloseToTurn(const NodeID from_node,
-                                              const EdgeID turn_edge,
-                                              const bool traversed_in_reverse,
-                                              const NodeID to_node) const;
+    [[nodiscard]] util::Coordinate GetCoordinateCloseToTurn(const NodeID from_node,
+                                                            const EdgeID turn_edge,
+                                                            const bool traversed_in_reverse,
+                                                            const NodeID to_node) const;
 
     /* When extracting the coordinates, we first extract all coordinates. We don't care about most
      * of them, though.
@@ -90,22 +86,19 @@ class CoordinateExtractor
      * The optional length cache needs to store the accumulated distance up to the respective
      * coordinate index [0,d(0,1),...]
      */
-    OSRM_ATTR_WARN_UNUSED
-    std::vector<util::Coordinate>
+    [[nodiscard]] std::vector<util::Coordinate>
     TrimCoordinatesToLength(std::vector<util::Coordinate> coordinates,
                             const double desired_length,
                             const std::vector<double> &length_cache = {}) const;
 
-    OSRM_ATTR_WARN_UNUSED
-    std::vector<double> PrepareLengthCache(const std::vector<util::Coordinate> &coordinates,
-                                           const double limit) const;
+    [[nodiscard]] std::vector<double>
+    PrepareLengthCache(const std::vector<util::Coordinate> &coordinates, const double limit) const;
 
     /* when looking at a set of coordinates, this function allows trimming the vector to a smaller,
      * only containing coordinates up to a given distance along the path. The last coordinate might
      * be interpolated
      */
-    OSRM_ATTR_WARN_UNUSED
-    std::vector<util::Coordinate>
+    [[nodiscard]] std::vector<util::Coordinate>
     TrimCoordinatesByLengthFront(std::vector<util::Coordinate> coordinates,
                                  const double desired_length) const;
 
@@ -130,10 +123,9 @@ class CoordinateExtractor
      *
      * for fixpoint `b`, vector_base `d` and vector_head `e`
      */
-    OSRM_ATTR_WARN_UNUSED
-    util::Coordinate GetCorrectedCoordinate(const util::Coordinate fixpoint,
-                                            const util::Coordinate vector_base,
-                                            const util::Coordinate vector_head) const;
+    [[nodiscard]] util::Coordinate GetCorrectedCoordinate(const util::Coordinate fixpoint,
+                                                          const util::Coordinate vector_base,
+                                                          const util::Coordinate vector_head) const;
 
     /* generate a uniform vector of coordinates in same range distances
      *
@@ -143,8 +135,7 @@ class CoordinateExtractor
      * Into:
      * x -- x -- x -- x -- x - x
      */
-    OSRM_ATTR_WARN_UNUSED
-    std::vector<util::Coordinate>
+    [[nodiscard]] std::vector<util::Coordinate>
     SampleCoordinates(const std::vector<util::Coordinate> &coordinates,
                       const double length,
                       const double rate) const;

include/guidance/motorway_handler.hpp

@@ -7,7 +7,6 @@
 #include "guidance/intersection_handler.hpp"
 #include "guidance/is_through_street.hpp"
 
-#include "util/attributes.hpp"
 #include "util/node_based_graph.hpp"
 
 #include <vector>
@@ -42,18 +41,14 @@ class MotorwayHandler final : public IntersectionHandler
                             Intersection intersection) const override final;
 
   private:
-    OSRM_ATTR_WARN_UNUSED
-    Intersection handleSliproads(const NodeID intersection_node_id,
-                                 Intersection intersection) const;
+    [[nodiscard]] Intersection handleSliproads(const NodeID intersection_node_id,
+                                               Intersection intersection) const;
 
-    OSRM_ATTR_WARN_UNUSED
-    Intersection fromMotorway(const EdgeID via_edge, Intersection intersection) const;
+    [[nodiscard]] Intersection fromMotorway(const EdgeID via_edge, Intersection intersection) const;
 
-    OSRM_ATTR_WARN_UNUSED
-    Intersection fromRamp(const EdgeID via_edge, Intersection intersection) const;
+    [[nodiscard]] Intersection fromRamp(const EdgeID via_edge, Intersection intersection) const;
 
-    OSRM_ATTR_WARN_UNUSED
-    Intersection fallback(Intersection intersection) const;
+    [[nodiscard]] Intersection fallback(Intersection intersection) const;
 };
 
 } // namespace osrm::guidance

include/guidance/parsing_toolkit.hpp

@@ -7,8 +7,6 @@
 #include <boost/algorithm/string.hpp>
 #include <boost/tokenizer.hpp>
 
-#include "util/attributes.hpp"
-
 namespace osrm::extractor::guidance
 {
 
@@ -21,8 +19,7 @@ namespace osrm::extractor::guidance
 // will be corrected to left|throught, since the final lane is not drivable.
 // This is in contrast to a situation with lanes:psv:forward=0 (or not set) where left|through|
 // represents left|through|through
-OSRM_ATTR_WARN_UNUSED
-inline std::string
+[[nodiscard]] inline std::string
 trimLaneString(std::string lane_string, std::int32_t count_left, std::int32_t count_right)
 {
     if (count_left)
@@ -68,8 +65,8 @@ trimLaneString(std::string lane_string, std::int32_t count_left, std::int32_t co
 // turn:lanes=left|through|through|right
 // vehicle:lanes=yes|yes|no|yes
 // bicycle:lanes=yes|no|designated|yes
-OSRM_ATTR_WARN_UNUSED
-inline std::string applyAccessTokens(std::string lane_string, const std::string &access_tokens)
+[[nodiscard]] inline std::string applyAccessTokens(std::string lane_string,
+                                                   const std::string &access_tokens)
 {
     using tokenizer = boost::tokenizer<boost::char_separator<char>>;
     boost::char_separator<char> sep("|", "", boost::keep_empty_tokens);

include/guidance/turn_analysis.hpp

@@ -17,7 +17,6 @@
 #include "guidance/turn_classification.hpp"
 #include "guidance/turn_handler.hpp"
 
-#include "util/attributes.hpp"
 #include "util/node_based_graph.hpp"
 
 #include <cstdint>
@@ -47,13 +46,11 @@ class TurnAnalysis
 
     /* Full Analysis Process for a single node/edge combination. Use with caution, as the process is
      * relatively expensive */
-    OSRM_ATTR_WARN_UNUSED
-    Intersection operator()(const NodeID node_prior_to_intersection,
-                            const EdgeID entering_via_edge) const;
+    [[nodiscard]] Intersection operator()(const NodeID node_prior_to_intersection,
+                                          const EdgeID entering_via_edge) const;
 
     // Select turn types based on the intersection shape
-    OSRM_ATTR_WARN_UNUSED
-    Intersection
+    [[nodiscard]] Intersection
     AssignTurnTypes(const NodeID from_node,
                     const EdgeID via_eid,
                     const extractor::intersection::IntersectionView &intersection) const;