[Bug middle-end/69258] Flexible arrays break TBAA

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69258

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Using

struct Xflex { int n; int a[]; };

doesn't fix it (as expected).