[libstdc++] Don't access fpos_t.__state on uClibc w/o wchar support

[Bernardo Innocenti]

Pétur Runólfsson wrote:
> Gabriel Dos Reis wrote:
> 
>>| This won't work because fpos<mbstate_t> is also used for narrow streams.
>>
>>then we've get a design problem then.
> 
> This is required by the standard (char_traits<char>::pos_type is
> streampos which is fpos<mbstate_t>), so there is not much that can
> be done about it.

The problem with uClibc is not that mbstate_t is not present. It's
that the fpos_t structure does not contain a __state member when
the library is configured without wchar support.

We just need to disable code that needs that missing member and
perhaps return a default value instead.

Actually, the field name in uClibc is __mbstate instead of __state.
I guess C library implementations are free to name private members
whatever they like.

I also have a philosophical question: does libstdc++ need to
provide all the features mandated by the standard even when
the underlying C library doesn't support them properly?

In embedded projects, I'd rather like an incomplete libstdc++
than a needlessly fat one. I don't use locales, UTF8 or wide
streams, therefore I'd like to drop all code for dealing with
them.

-- 
  // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/

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