https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63645
--- Comment #3 from M Welinder <terra at gnome dot org> ---
Why do you think so?
I think it is covered by this:
6.5 Expressions
[...]
[#7] An object shall have its stored value accessed only by
an lvalue expression that has one of the following types:63)
-- a type compatible with the effective type of the
object,
[...]
-- an aggregate or union type that includes one of the
aforementioned types among its members (including,
recursively, a member of a subaggregate or contained
union), or
[...]
