Or you could just not worry about it and assume the language is well-defined with precise methodologies grounded on common sense like Ada.
https://gcc.gnu.org/onlinedocs/gnat_rm/Value_005fSize-and-Ob...
On second thought, who cares about reading its for squares and nerds. I would rather spend 2 hours Google searching what is an octet and finding out how enums are represented... :p