Fix Linux build & some warnings (#6438)

* Fix linux deps debug build

* Use the same DL_CACHE for release build when building debug version of deps on Linux.
This prevents downloading the same source packages twice, and avoid downloading again after deleting the build dir.

* Fix debug build

* Fix warnings "loop variable creates a copy from type" and "loop variable binds to a temporary constructed from type"

src/libslic3r/Clipper2Utils.cpp

@@ -23,7 +23,7 @@ Clipper2Lib::Paths64 Slic3rPoints_to_Paths64(const std::vector<T>& in)
 {
     Clipper2Lib::Paths64 out;
     out.reserve(in.size());
-    for (const T item: in) {
+    for (const T& item: in) {
         Clipper2Lib::Path64 path;
         path.reserve(item.size());
         for (const Slic3r::Point& point : item.points)

src/libslic3r/Emboss.cpp

@@ -334,8 +334,8 @@ bool Emboss::divide_segments_for_close_point(ExPolygons &expolygons, double dist
                 const Points &poly_pts = poly.points;
                 const Point &line_a = poly_pts[id.point_index];
                 const Point &line_b = (!ids.is_last_point(id)) ? poly_pts[id.point_index + 1] : poly_pts.front();
-                assert(line_a == lines[index].a.cast<int>());
-                assert(line_b == lines[index].b.cast<int>());
+                assert(line_a == lines[index].a.cast<coord_t>());
+                assert(line_b == lines[index].b.cast<coord_t>());
                 if (p == line_a || p == line_b) continue;
 
                 divs.emplace_back(p, index);

src/libslic3r/Format/bbs_3mf.cpp

@@ -4622,7 +4622,7 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
                 its.vertices.assign(sub_object->geometry.vertices.begin(), sub_object->geometry.vertices.end());
 
                 // BBS
-                for (const std::string prop_str : sub_object->geometry.face_properties) {
+                for (const std::string& prop_str : sub_object->geometry.face_properties) {
                     FaceProperty face_prop;
                     face_prop.from_string(prop_str);
                     its.properties.push_back(face_prop);

src/libslic3r/Model.cpp

@@ -3538,7 +3538,7 @@ void check_model_ids_validity(const Model &model)
         for (const ModelInstance *model_instance : model_object->instances)
             check(model_instance->id());
     }
-    for (const auto mm : model.materials) {
+    for (const auto& mm : model.materials) {
         check(mm.second->id());
         check(mm.second->config.id());
     }

src/libslic3r/Preset.cpp

@@ -340,7 +340,7 @@ void Preset::normalize(DynamicPrintConfig &config)
                 static_cast<ConfigOptionVectorBase*>(opt)->resize(n, defaults.option(key));
         }
         // The following keys are mandatory for the UI, but they are not part of FullPrintConfig, therefore they are handled separately.
-        for (const std::string &key : { "filament_settings_id" }) {
+        for (const std::string key : { "filament_settings_id" }) {
             auto *opt = config.option(key, false);
             assert(opt == nullptr || opt->type() == coStrings);
             if (opt != nullptr && opt->type() == coStrings)

src/libslic3r/Print.cpp

@@ -2925,7 +2925,7 @@ DynamicConfig PrintStatistics::config() const
 DynamicConfig PrintStatistics::placeholders()
 {
     DynamicConfig config;
-    for (const std::string &key : {
+    for (const std::string key : {
         "print_time", "normal_print_time", "silent_print_time",
         "used_filament", "extruded_volume", "total_cost", "total_weight",
         "initial_tool", "total_toolchanges", "total_wipe_tower_cost", "total_wipe_tower_filament"})

src/libslic3r/PrintConfig.cpp

@@ -5329,11 +5329,11 @@ void PrintConfigDef::init_extruder_option_keys()
         "retraction_length",
         "retraction_minimum_travel",
         "retraction_speed",
+        "travel_slope",
         "wipe",
         "wipe_distance",
         "z_hop",
-        "z_hop_types",
-        "travel_slope"
+        "z_hop_types"
     };
     assert(std::is_sorted(m_extruder_retract_keys.begin(), m_extruder_retract_keys.end()));
 }

src/libslic3r/ShortestPath.hpp

@@ -29,7 +29,7 @@ template<typename T> inline void reorder_by_shortest_traverse(std::vector<T> &po
 {
     Points start_point;
     start_point.reserve(polylines_out.size());
-    for (const T contour : polylines_out) start_point.push_back(contour.points.front());
+    for (const T& contour : polylines_out) start_point.push_back(contour.points.front());
 
     std::vector<Points::size_type> order = chain_points(start_point);
 

src/libslic3r/TreeSupport.cpp

@@ -482,7 +482,7 @@ static bool move_inside_expolys(const ExPolygons& polygons, Point& from, double
         // because we compare with vsize2_with_unscale here (no division by zero), we also need to compare by vsize2_with_unscale inside the loop
         // to avoid integer rounding edge cases
         bool projected_p_beyond_prev_segment = dot_with_unscale(p1 - p0, from - p0) >= vsize2_with_unscale(p1 - p0);
-        for(const Point p2 : poly.contour.points)
+        for(const Point& p2 : poly.contour.points)
         {
             // X = A + Normal(B-A) * (((B-A) dot_with_unscale (P-A)) / VSize(B-A));
             //   = A +       (B-A) *  ((B-A) dot_with_unscale (P-A)) / VSize2(B-A);
@@ -1437,11 +1437,11 @@ void TreeSupport::generate_toolpaths()
 
     if (m_object->support_layer_count() > m_raft_layers) {
         const SupportLayer *ts_layer = m_object->get_support_layer(m_raft_layers);
-        for (const ExPolygon expoly : ts_layer->floor_areas)
+        for (const ExPolygon& expoly : ts_layer->floor_areas)
             raft_areas.push_back(expoly);
-        for (const ExPolygon expoly : ts_layer->roof_areas)
+        for (const ExPolygon& expoly : ts_layer->roof_areas)
             raft_areas.push_back(expoly);
-        for (const ExPolygon expoly : ts_layer->base_areas)
+        for (const ExPolygon& expoly : ts_layer->base_areas)
             raft_areas.push_back(expoly);
     }
 
@@ -3628,7 +3628,7 @@ const ExPolygons& TreeSupportData::get_avoidance(coordf_t radius, size_t layer_n
 Polygons TreeSupportData::get_contours(size_t layer_nr) const
 {
     Polygons contours;
-    for (const ExPolygon expoly : m_layer_outlines[layer_nr]) {
+    for (const ExPolygon& expoly : m_layer_outlines[layer_nr]) {
         contours.push_back(expoly.contour);
     }
 
@@ -3638,7 +3638,7 @@ Polygons TreeSupportData::get_contours(size_t layer_nr) const
 Polygons TreeSupportData::get_contours_with_holes(size_t layer_nr) const
 {
     Polygons contours;
-    for (const ExPolygon expoly : m_layer_outlines[layer_nr]) {
+    for (const ExPolygon& expoly : m_layer_outlines[layer_nr]) {
         for(int i=0;i<expoly.num_contours();i++)
             contours.push_back(expoly.contour_or_hole(i));
     }