Re: [boost] lexical_cast.hpp:102: error: `wstring' is not a member of `std' ?

From: Jonathan Wakely (cow_at_[hidden])
Date: 2004-09-27 04:47:51

On Mon, Sep 27, 2004 at 01:17:12PM +0900, Rob wrote:

> Hello,
> 
> I'm not a boost expert, but I'm using LyX, which has boost (version 1.31.0)
> included in its source code.
> 
> I have FreeBSD (4.10) and use gcc 3.4.2. When I compile LyX, I get
> an error from boost:
> 
> [...]
> ../../boost/boost/lexical_cast.hpp:102: error: `wstring' is not a member of 
> `std'
> ../../boost/boost/lexical_cast.hpp:102: error: `wstring' is not a member of 
> `std'
> ../../boost/boost/lexical_cast.hpp:103: error: template argument 1 is 
> invalid
> ../../boost/boost/lexical_cast.hpp:103: error: explicit specialization of 
> non-template `<type error>'
> ../../boost/boost/lexical_cast.hpp:162: error: declaration of `operator>>' 
> as non-function
> ../../boost/boost/lexical_cast.hpp:162: error: expected `;' before '(' token
> ../../boost/boost/lexical_cast.hpp:168: error: expected `;' before "private"
> 
> 
> When I reported this to the LyX list, I was told to forward the problem
> to the boost list. There may be a problem here with FreeBSD, gcc 3.4.2 and
> boost. Any idea what is going on here?

FreeBSD's wchar_t support is limited, so GCC does not enable any
wide-char support in the C++ stdlib

All uses of wstring/char_t/wstream etc. are be guarded by
BOOST_NO_WSTRING so they aren't compiled on platforms without wchar
support in the stdlib. BOOST_NO_WSTRING will get set automatically
because the stdlib does not define _GLIBCXX_USE_WCHAR_T on FreeBSD.

However, Boost 1.31 was released before GCC 3.4.1, which changed the
stdlib macros from _GLIBCPP_blahblah to _GLIBCXX_blahblah and so Boost's
config fails to configure correctly for this compiler. You could try
taking the boost/config/stdlib/libstdcppv3.hpp header from CVS, but note
that there are additional problems with GCC 3.4.x and Boost due to GCC
3.4 unconditionally defining _REENTRANT. See GCC PR 11953 for details.
(I've written a summary of this issue, but it's sitting on my hard drive
at home somewhere. I need to send it to this list...)

In short, you must define either BOOST_DISABLE_THREADS or compile with
-pthreads to avoid linker errors from the pthread_xxx functions.

Hope that helps,

jon

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