structure problem - error or warning?

[Joaquim Martillo]

I  think  warning  for illegal member use rather than error dates to the
ancient history of the c compiler when there were  not  unions  and  you
used to able to get member elements from an object which was not defined
as a structure.  I seem to remember two different structures  could  not
have  the  same member.  Some system code was written and depends on the
ability to get members from objects not defined as structures, hence the
warning.