Members of an inline namespace can be used in most respects as though they were members
of the enclosing namespace.
member of the inline namespace can subsequently be partially
), or explicitly specialized ([temp.expl.spec]
though it were a member of the enclosing namespace.
Finally, looking up a name in the
enclosing namespace via explicit qualification ([namespace.qual]
) will include
members of the inline namespace even if
there are declarations of that name in the enclosing namespace.