Effects: Implicitly creates objects (
[intro.object]) within the denoted region
consisting of an object
a of type
T
whose address is
p, and
objects nested within
a,
as follows:
The object representation of
a
is the contents of the storage prior to the call to
start_lifetime_as. The value of each created object
o
of trivially-copyable type
U
is determined in the same manner as for a call
to
bit_cast<U>(E) (
[bit.cast]),
where
E is an lvalue of type
U denoting
o,
except that the storage is not accessed
.