During the evaluation of an expression E
as a core constant expression,
and uses of *this
that refer to an object or reference
whose lifetime did not begin with the evaluation of E
are treated as referring to a specific instance of that object or reference
whose lifetime and that of all subobjects (including all union members)
includes the entire constant evaluation.
For such a reference that is not usable in constant expressions,
the reference is treated as binding to
an unspecified object of the referenced type
whose lifetime and that of all subobjects includes
the entire constant evaluation and whose dynamic type is constexpr-unknown.