Fixed some more GCC warnings

src/libslic3r/Fill/FillRectilinear.cpp

@@ -2178,11 +2178,11 @@ static std::vector<MonotonicRegionLink> chain_monotonic_regions(
 	float best_path_length = std::numeric_limits<float>::max();
 
 	struct NextCandidate {
-        MonotonicRegion    *region;
+        MonotonicRegion    *region = nullptr;
         AntPath  	        *link;
         AntPath  	        *link_flipped;
         float                probability;
-		bool 		         dir;
+        bool 		         dir = false;
 	};
 	std::vector<NextCandidate> next_candidates;
 
@@ -2317,6 +2317,7 @@ static std::vector<MonotonicRegionLink> chain_monotonic_regions(
                 queue.pop_back();
             }
 			// Extend the path.
+            assert(next_candidate.region);
 			MonotonicRegion *next_region = next_candidate.region;
 			bool              next_dir    = next_candidate.dir;
             total_length += next_region->length(next_dir) + path_matrix(*path_end.region, path_end.flipped, *next_region, next_dir).length;

src/libslic3r/PresetBundle.cpp

@@ -800,10 +800,9 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
             compatible_printers_condition = compatible_printers_condition_values[1];
 			compatible_prints_condition   = compatible_prints_condition_values.front();
 			Preset                *loaded = nullptr;
-			if (is_external) {
+            if (is_external)
-				auto [aloaded, modified] = this->filaments.load_external_preset(name_or_path, name, old_filament_profile_names->values.front(), config);
+                loaded = this->filaments.load_external_preset(name_or_path, name, old_filament_profile_names->values.front(), config).first;
-                loaded = aloaded;
+            else {
-			} else {
                 // called from Config Wizard.
 				loaded= &this->filaments.load_preset(this->filaments.path_from_name(name), name, config);
 				loaded->save();

src/libslic3r/ShortestPath.cpp

@@ -1553,7 +1553,8 @@ static inline void reorder_by_two_exchanges_with_segment_flipping(std::vector<Fl
 		size_t crossover1_pos_final = std::numeric_limits<size_t>::max();
 		size_t crossover2_pos_final = std::numeric_limits<size_t>::max();
 		size_t crossover_flip_final = 0;
-        for (const auto& [longest_connection_length, longest_connection_idx] : connection_lengths) {
+        for (const std::pair<double, size_t>& first_crossover_candidate : connection_lengths) {
+            size_t longest_connection_idx = first_crossover_candidate.second;
 			connection_tried[longest_connection_idx] = true;
 			// Find the second crossover connection with the lowest total chain cost.
 			size_t crossover_pos_min  = std::numeric_limits<size_t>::max();
@@ -1628,7 +1629,8 @@ static inline void reorder_by_three_exchanges_with_segment_flipping(std::vector<
 		size_t crossover2_pos_final = std::numeric_limits<size_t>::max();
 		size_t crossover3_pos_final = std::numeric_limits<size_t>::max();
 		size_t crossover_flip_final = 0;
-        for (const auto& [longest_connection_length, longest_connection_idx] : connection_lengths) {
+        for (const std::pair<double, size_t> &first_crossover_candidate : connection_lengths) {
+            size_t longest_connection_idx = first_crossover_candidate.second;
             connection_tried[longest_connection_idx] = true;
 			// Find the second crossover connection with the lowest total chain cost.
 			double crossover_cost_min = connections.back().cost;
@@ -1784,7 +1786,8 @@ static inline void reorder_by_three_exchanges_with_segment_flipping2(std::vector
 #else /* NDEBUG */
 		Matrixd segment_end_point_distance_matrix = Matrixd::Constant(4 * 4, 4 * 4, std::numeric_limits<double>::max());
 #endif /* NDEBUG */
-        for (const auto& [longest_connection_length, longest_connection_idx] : connection_lengths) {
+        for (const std::pair<double, size_t> &first_crossover_candidate : connection_lengths) {
+            size_t longest_connection_idx = first_crossover_candidate.second;
             connection_tried[longest_connection_idx] = true;
             // Find the second crossover connection with the lowest total chain cost.
 			double crossover_cost_min = connections.back().cost;

src/slic3r/GUI/PresetComboBoxes.cpp

@@ -201,7 +201,7 @@ void PresetComboBox::update_selection()
 
     if (!cell) return;
 
-    g_object_set(G_OBJECT(cell), "ellipsize", PANGO_ELLIPSIZE_END, NULL);
+    g_object_set(G_OBJECT(cell), "ellipsize", PANGO_ELLIPSIZE_END, (char*)NULL);
 
     // Only the list of cells must be freed, the renderer isn't ours to free
     g_list_free(cells);

tests/libslic3r/test_elephant_foot_compensation.cpp

@@ -16,6 +16,7 @@ using namespace Slic3r;
 namespace Slic3r {
 	ClipperLib::Path mittered_offset_path_scaled(const Points& contour, const std::vector<float>& deltas, double miter_limit);
 
+#if 0
 	static Points mittered_offset_path_scaled_points(const Points& contour, const std::vector<float>& deltas, double miter_limit)
 	{
 		Points out;
@@ -29,6 +30,7 @@ namespace Slic3r {
 		}
 		return out;
 	}
+#endif
 }
 
 static ExPolygon spirograph_gear_1mm()
@@ -494,6 +496,7 @@ SCENARIO("Elephant foot compensation", "[ElephantFoot]") {
 		ExPolygon input = spirograph_gear_1mm().simplify(SCALED_EPSILON).front();
 		ExPolygon output;
 		std::vector<float> deltas(input.contour.points.size(), scale_(1.));
+                // mittered_offset_path_scaled_points is commented out somewhere above
 		output.contour.points = Slic3r::mittered_offset_path_scaled_points(input.contour.points, deltas, 2.);
 #ifdef TESTS_EXPORT_SVGS
 		{

tests/libslic3r/test_marchingsquares.cpp

@@ -326,7 +326,9 @@ static void recreate_object_from_rasters(const std::string &objname, float lh) {
     double                      disp_w = 120.96;
     double                      disp_h = 68.04;
 
+#ifndef NDEBUG
     size_t cntr = 0;
+#endif
     for (ExPolygons &layer : layers) {
         auto rst = create_raster(res, disp_w, disp_h);