Re: [v3 PATCH] Reduce the size of variant, it doesn't need an index of type size_t internally.

[Ville Voutilainen <ville dot voutilainen at gmail dot com>]

Cleanups based on review; there's no longer any public typedefs added
to variant,
and the test is greatly simpler with much less trickery.

2017-01-11  Ville Voutilainen  <ville.voutilainen@gmail.com>

    Reduce the size of variant, it doesn't need an index of
    type size_t internally.
    * include/std/variant (parse_numbers.h): New include.
    (__select_index): New.
    (_Variant_storage<false, _Types...>::_M_reset_impl): Use
    _index_type for comparison with variant_npos.
    (_Variant_storage<false, _Types...>::__index_type): New.
    (_Variant_storage<false, _Types...>::_M_index): Change the
    type from size_t to __index_type.
    (_Variant_storage<true, _Types...>::__index_type): New.
    (_Variant_storage<true, _Types...>::_M_index): Change the
    type from size_t to __index_type.
    (_Variant_base::_M_valid): Use _Storage::__index_type
    for comparison with variant_npos.
    (variant::index): Use _Base::_Storage::__index_type
    for comparison with variant_npos.
    * testsuite/20_util/variant/index_type.cc: New.

Attachment: variant-index2.diff
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