Fix of 2.3 rc1 can't load its own 3mf files (if they contain custom gcode) #5550

The issue was handling of the special "default_filament_profile" vector,
which is not being normalized in length to the number of extruders,
as this vector is being shown to the user at the Printer dependencies page,
and we don't want to present empty fields there, if the default filament
profile was not defined in the system preset.

src/libslic3r/Preset.cpp

@@ -1152,11 +1152,14 @@ inline t_config_option_keys deep_diff(const ConfigBase &config_this, const Confi
         if (this_opt != nullptr && other_opt != nullptr && *this_opt != *other_opt)
         {
             if (opt_key == "bed_shape" || opt_key == "thumbnails" || opt_key == "compatible_prints" || opt_key == "compatible_printers") {
+                // Scalar variable, or a vector variable, which is independent from number of extruders,
+                // thus the vector is presented to the user as a single input.
                 diff.emplace_back(opt_key);
-                continue;
+            } else if (opt_key == "default_filament_profile") {
-            }
+                // Ignore this field, it is not presented to the user, therefore showing a "modified" flag for this parameter does not help.
-            switch (other_opt->type())
+                // Also the length of this field may differ, which may lead to a crash if the block below is used.
-            {
+            } else {
+                switch (other_opt->type()) {
                 case coInts:    add_correct_opts_to_diff<ConfigOptionInts       >(opt_key, diff, config_other, config_this);  break;
                 case coBools:   add_correct_opts_to_diff<ConfigOptionBools      >(opt_key, diff, config_other, config_this);  break;
                 case coFloats:  add_correct_opts_to_diff<ConfigOptionFloats     >(opt_key, diff, config_other, config_this);  break;
@@ -1167,6 +1170,7 @@ inline t_config_option_keys deep_diff(const ConfigBase &config_this, const Confi
                 }
             }
         }
+    }
     return diff;
 }
 

src/libslic3r/PresetBundle.cpp

@@ -86,9 +86,8 @@ PresetBundle::PresetBundle() :
             preset.config.optptr(key, true);
         if (i == 0) {
             preset.config.optptr("default_print_profile", true);
-            preset.config.option<ConfigOptionStrings>("default_filament_profile", true)->values = { "" };
+            preset.config.option<ConfigOptionStrings>("default_filament_profile", true);
-        }
+        } else {
-        else {
             preset.config.optptr("default_sla_print_profile", true);
             preset.config.optptr("default_sla_material_profile", true);
         }
@@ -752,7 +751,7 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
 	switch (printer_technology) {
 	case ptFFF:
 		config.option<ConfigOptionString>("default_print_profile", true);
-		config.option<ConfigOptionStrings>("default_filament_profile", true)->values.resize(num_extruders, std::string());
+        config.option<ConfigOptionStrings>("default_filament_profile", true);
 		break;
 	case ptSLA:
 		config.option<ConfigOptionString>("default_sla_print_profile", true);

src/libslic3r/PrintConfig.cpp

@@ -3378,6 +3378,8 @@ void DynamicPrintConfig::set_num_extruders(unsigned int num_extruders)
     const auto &defaults = FullPrintConfig::defaults();
     for (const std::string &key : print_config_def.extruder_option_keys()) {
         if (key == "default_filament_profile")
+            // Don't resize this field, as it is presented to the user at the "Dependencies" page of the Printer profile and we don't want to present
+            // empty fields there, if not defined by the system profile.
             continue;
         auto *opt = this->option(key, false);
         assert(opt != nullptr);