[Bug c/77650] struct with a nested flexible array followed by another member accepted

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77650

--- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> ---
Documenting the semantics of this extension would work, though to be usable
safely, GCC would also need to change to recognize that the nested flexible
array member aliases the subsequent members and treat the two sets as if they
were declared in a union.  My own preference, however, would be to reject such
constructs in user code.  As long as changing Glibc to use a zero-length array
is feasible (those would continue to be accepted in this context), it should be
possible to do.