Third, for
F
to be a viable function, there shall exist for each
argument an
implicit conversion sequence (
[over.best.ics]) that
converts that argument to the corresponding parameter of
F. If the parameter has reference type, the implicit conversion sequence
includes the operation of binding the reference, and the fact that
an lvalue reference to non-
const cannot bind to an rvalue
and that an rvalue reference cannot bind to an lvalue
can affect
the viability of the function (see
[over.ics.ref])
.