Is segmentation fault actual undefined behavior when we refer to a non-static data-member

Question

I had read the following rule and I\'ve been trying to write an example, which reflects one. The rule is from 3.8/5 N3797:

Before the lifetime of an o

Answer 1

Rule 3.8/5 is about the time outside of the construction/destruction of an object but inside the allocation/release of the memory in which the object resides. The following demonstrates the points outside of the lifetime of an object:

void *buffer = malloc(sizeof(A));
// outside of lifetime of a
// a->b is undefined
A* a = new (buffer) A();
// within lifetime of a
// a->b is valid
a->~A();
// outside of lifetime of a
// a->b is undefined
free(buffer);

Technically, your post doesn't actually reflect rule 3.8/5, because you are not accessing the object outside of its lifetime. You are simply casting random memory as an instance.