field = variant_get_current_field(variant);
field_declaration = field->definition->declaration;
field_declaration->copy(dest, fdest, src, fsrc, field->definition);
fsrc->variant_end(src, variant_declaration);
field = variant_get_current_field(variant);
field_declaration = field->definition->declaration;
field_declaration->copy(dest, fdest, src, fsrc, field->definition);
fsrc->variant_end(src, variant_declaration);