structure problem - error or warning?

[Doug Gwyn <gwyn>]

The reason your compiler gives a nonfatal warning on misuse of
structure members (z.w where w is a member of a different structure
type) is that in the early days of C, this was a supported usage.
Now that stronger typing is creeping into C, it really should be
considered an error (if one WANTS that behavior he can get it by
appropriate use of type-casts).  "Compatibility forever"