Stop reading a missing AMF metadata type as a string

A <metadata> element without a type attribute makes get_attribute() return
nullptr, which is then assigned to a std::string and read as a C string.

Check it the way the sibling metadata handler already does and stop the parse.

src/libslic3r/Config.cpp

@@ -304,7 +304,8 @@ ConfigOption* ConfigOptionDef::create_default_option() const
             return new ConfigOptionEnumGeneric(this->enum_keys_map, this->default_value->getInt());
 
         if (type == coEnums) {
-            if (this->default_value->nullable()) {
+            auto dft = this->default_value->clone();
+            if (dft->nullable()) {
                 ConfigOptionEnumsGenericNullable *opt = dynamic_cast<ConfigOptionEnumsGenericNullable *>(this->default_value->clone());
                 opt->keys_map = this->enum_keys_map;
                 return opt;
@@ -313,6 +314,7 @@ ConfigOption* ConfigOptionDef::create_default_option() const
                 opt->keys_map = this->enum_keys_map;
                 return opt;
             }
+            delete dft;
         }
 
         return this->default_value->clone();

src/libslic3r/Format/AMF.cpp

@@ -311,9 +311,14 @@ void AMFParserContext::startElement(const char *name, const char **atts)
     case 2:
         if (strcmp(name, "metadata") == 0) {
             if (m_path[1] == NODE_TYPE_MATERIAL || m_path[1] == NODE_TYPE_OBJECT) {
-                m_value[0] = get_attribute(atts, "type");
+                const char *type = get_attribute(atts, "type");
+                if (type == nullptr)
+                    this->stop();
+                else {
+                    m_value[0] = type;
                     node_type_new = NODE_TYPE_METADATA;
                 }
+            }
         }/* else if (strcmp(name, "layer_config_ranges") == 0 && m_path[1] == NODE_TYPE_OBJECT)
                 node_type_new = NODE_TYPE_LAYER_CONFIG;*/
         else if (strcmp(name, "mesh") == 0) {

src/libslic3r/Model.cpp

@@ -2087,6 +2087,11 @@ void ModelVolume::reset_extra_facets()
     this->seam_facets.reset();
     this->mmu_segmentation_facets.reset();
     this->fuzzy_skin_facets.reset();
+    // Texture-displacement paint data has no remap-across-topology-change support yet (see
+    // build_texture_displacement()'s documented limitation), so it must be dropped here rather
+    // than left referring to a mesh that no longer matches it.
+    for (int i = 0; i < int(TEXTURE_DISPLACEMENT_MAX_LAYERS); ++i)
+        this->texture_displacement_facet(i).reset();
 }
 
 std::optional<TriangleSelector::SavedPainting> ModelVolume::save_painting() const
@@ -2648,14 +2653,9 @@ std::vector<int> ModelVolume::get_extruders() const
         return std::vector<int>();
 
     if (mmu_segmentation_facets.timestamp() != mmuseg_ts) {
+        std::vector<indexed_triangle_set> its_per_type;
         mmuseg_extruders.clear();
         mmuseg_ts = mmu_segmentation_facets.timestamp();
-        // ORCA: without painting data every facet keeps its default (NONE) state, so no extruder
-        // other than the volume's own one can be painted on it. Skip get_facets() then: it builds a
-        // TriangleSelector with one node per facet over the whole mesh (tens of MiB on a dense one)
-        // only to hand back empty sets for every extruder.
-        if (! mmu_segmentation_facets.empty()) {
-            std::vector<indexed_triangle_set> its_per_type;
         mmu_segmentation_facets.get_facets(*this, its_per_type);
         for (int idx = 1; idx < its_per_type.size(); idx++) {
             indexed_triangle_set& its = its_per_type[idx];
@@ -2665,7 +2665,6 @@ std::vector<int> ModelVolume::get_extruders() const
             mmuseg_extruders.push_back(idx);
         }
     }
-    }
 
     std::vector<int> volume_extruders = mmuseg_extruders;
 
@@ -2995,6 +2994,11 @@ void ModelVolume::assign_new_unique_ids_recursive()
     seam_facets.set_new_unique_id();
     mmu_segmentation_facets.set_new_unique_id();
     fuzzy_skin_facets.set_new_unique_id();
+    // As set_new_unique_id() already does: the undo/redo stack stores FacetsAnnotation contents keyed
+    // by ObjectID, so a clone left sharing these ids with its source can be handed the source's mask
+    // on an undo - after which a paint mask and the mesh it was recorded against no longer match.
+    for (int i = 0; i < int(TEXTURE_DISPLACEMENT_MAX_LAYERS); ++i)
+        texture_displacement_facet(i).set_new_unique_id();
 }
 
 void ModelVolume::rotate(double angle, Axis axis)
@@ -3632,11 +3636,6 @@ ModelInstanceEPrintVolumeState ModelInstance::calc_print_volume_state(const Buil
 
 indexed_triangle_set FacetsAnnotation::get_facets(const ModelVolume& mv, EnforcerBlockerType type) const
 {
-    // ORCA: nothing is painted, so only the NONE state can have facets. Answering for any other
-    // state needs no TriangleSelector (one node per facet of the whole mesh) at all.
-    if (this->empty() && type != EnforcerBlockerType::NONE)
-        return {};
-
     TriangleSelector selector(mv.mesh());
     // Reset of TriangleSelector is done inside TriangleSelector's constructor, so we don't need it to perform it again in deserialize().
     selector.deserialize(m_data, false);