https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88223
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
The C standard is unclear here (C18, 6.2.6.1/7).
union { struct X { int i; int j; } x; struct Y { int i; int j; } y; } u;
u.x.i = 1;
u.y.j = 1;
after the second store does u.y.i have unspecified value? Because the
union member is y and there are no bytes that are not also in the member x.
I'm probably missing the correct place to look at here.
