Merge pull request #14997 from neikeq/issue-14988

Marshal NULL MonoString* as empty Godot string

modules/mono/editor/csharp_project.cpp

@@ -54,7 +54,7 @@ String generate_core_api_project(const String &p_dir, const Vector<String> &p_fi
 		ERR_FAIL_V(String());
 	}
 
-	return ret ? GDMonoMarshal::mono_string_to_godot((MonoString *)ret) : "";
+	return ret ? GDMonoMarshal::mono_string_to_godot((MonoString *)ret) : String();
 }
 
 String generate_editor_api_project(const String &p_dir, const String &p_core_dll_path, const Vector<String> &p_files) {
@@ -75,7 +75,7 @@ String generate_editor_api_project(const String &p_dir, const String &p_core_dll
 		ERR_FAIL_V(String());
 	}
 
-	return ret ? GDMonoMarshal::mono_string_to_godot((MonoString *)ret) : "";
+	return ret ? GDMonoMarshal::mono_string_to_godot((MonoString *)ret) : String();
 }
 
 String generate_game_project(const String &p_dir, const String &p_name, const Vector<String> &p_files) {
@@ -96,7 +96,7 @@ String generate_game_project(const String &p_dir, const String &p_name, const Ve
 		ERR_FAIL_V(String());
 	}
 
-	return ret ? GDMonoMarshal::mono_string_to_godot((MonoString *)ret) : "";
+	return ret ? GDMonoMarshal::mono_string_to_godot((MonoString *)ret) : String();
 }
 
 void add_item(const String &p_project_path, const String &p_item_type, const String &p_include) {

modules/mono/mono_gd/gd_mono_field.cpp

@@ -290,7 +290,7 @@ int GDMonoField::get_int_value(MonoObject *p_object) {
 
 String GDMonoField::get_string_value(MonoObject *p_object) {
 	MonoObject *val = get_value(p_object);
-	return val ? GDMonoMarshal::mono_string_to_godot((MonoString *)val) : String();
+	return GDMonoMarshal::mono_string_to_godot((MonoString *)val);
 }
 
 bool GDMonoField::has_attribute(GDMonoClass *p_attr_class) {

modules/mono/mono_gd/gd_mono_marshal.cpp

@@ -490,8 +490,9 @@ Variant mono_object_to_variant(MonoObject *p_obj, const ManagedType &p_type) {
 			return unbox<double>(p_obj);
 
 		case MONO_TYPE_STRING: {
-			String str = mono_string_to_godot((MonoString *)p_obj);
-			return str;
+			if (p_obj == NULL)
+				return Variant(); // NIL
+			return mono_string_to_godot_not_null((MonoString *)p_obj);
 		} break;
 
 		case MONO_TYPE_VALUETYPE: {

modules/mono/mono_gd/gd_mono_marshal.h

@@ -62,13 +62,20 @@ Variant::Type managed_to_variant_type(const ManagedType &p_type);
 String mono_to_utf8_string(MonoString *p_mono_string);
 String mono_to_utf16_string(MonoString *p_mono_string);
 
-_FORCE_INLINE_ String mono_string_to_godot(MonoString *p_mono_string) {
+_FORCE_INLINE_ String mono_string_to_godot_not_null(MonoString *p_mono_string) {
 	if (sizeof(CharType) == 2)
 		return mono_to_utf16_string(p_mono_string);
 
 	return mono_to_utf8_string(p_mono_string);
 }
 
+_FORCE_INLINE_ String mono_string_to_godot(MonoString *p_mono_string) {
+	if (p_mono_string == NULL)
+		return String();
+
+	return mono_string_to_godot_not_null(p_mono_string);
+}
+
 _FORCE_INLINE_ MonoString *mono_from_utf8_string(const String &p_string) {
 	return mono_string_new(mono_domain_get(), p_string.utf8().get_data());
 }