Is it undefined behavior to `reinterpret_cast` a `T*` to `T(*)[N]`?

Question

Consider the following scenario:

std::array a;
auto p = reinterpret_cast(a.data());
(*p)[0] = 42;

Is this

Answer 1

Yes the behaviour is undefined.

int* (the return type of a.data()) is a different type from int(*)[8], so you are breaking strict aliasing rules.

Naturally though (and this is more for the benefit of future readers),

int* p = a.data();

is perfectly valid, as is the ensuing expression p + n where the integral type n is between 0 and 8 inclusive.