Annex F (informative) Core undefined behavior [ub]

F.2 [basic]: Basics [ub.basic]

F.2.6[ub:lifetime.outside.pointer.virtual]
Specified in: [basic.life]

For a pointer pointing to an object outside of its lifetime, behavior is undefined if the pointer is implicitly converted ([conv.ptr]) to a pointer to a virtual base class (or base class of a virtual base class).
[Example 1: struct B {}; struct D : virtual B {}; void f() { D d; D* p = &d; d.~D(); B* b = p; // undefined behavior } — end example]