Upgrade to clang-tidy 18 (#6919)

unit_tests/library/route.cpp

@@ -239,7 +239,6 @@ void test_route_same_coordinates(bool use_json_only_api)
                 BOOST_CHECK(((void)name, true));
 
                 // nothing can be said about mode, contains mode of transportation
-                const auto mode = std::get<json::String>(step_object.values.at("mode")).value;
                 BOOST_CHECK(!name.empty());
 
                 const auto &maneuver =

unit_tests/partitioner/bisection_graph_view.cpp

@@ -16,12 +16,15 @@ using namespace osrm::util;
 
 BOOST_AUTO_TEST_SUITE(graph_view)
 
-static void shuffle(std::vector<EdgeWithSomeAdditionalData> &grid_edges)
+namespace
+{
+void shuffle(std::vector<EdgeWithSomeAdditionalData> &grid_edges)
 {
     std::random_device rd;
     std::mt19937 rng(rd());
     std::shuffle(grid_edges.begin(), grid_edges.end(), rng);
 }
+} // namespace
 
 BOOST_AUTO_TEST_CASE(separate_top_bottom)
 {

unit_tests/util/static_rtree.cpp

@@ -235,8 +235,6 @@ auto make_rtree(const boost::filesystem::path &path, FixtureT &fixture)
 template <typename RTreeT = TestStaticRTree, typename FixtureT>
 void construction_test(const std::string &path, FixtureT &fixture)
 {
-    std::string leaves_path;
-    std::string nodes_path;
     auto rtree = make_rtree<RTreeT>(path, fixture);
     LinearSearchNN<TestData> lsnn(fixture.coords, fixture.edges);