Size in Perl6 is not the same that the C one for : gumbo_element_s -- C size : 96 ; NC size : 104
Compiling a test file, this assume field name are the same
gumbo_element_s: GumboElement

For   children : c-size=16 / nc-size=16
For   tag : c-size=4 / nc-size=4
For   tag_namespace : c-size=4 / nc-size=4
For   original_tag : c-size=16 / nc-size=16
For   original_end_tag : c-size=16 / nc-size=16
For   start_pos : c-size=12 / nc-size=12
For   end_pos : c-size=12 / nc-size=12
For   attributes : c-size=16 / nc-size=16
Total C/NC : 96/96