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Date:	Thu, 25 Jun 2009 15:55:43 -0700 (PDT)
From:	Match Point <qihongwang AT gmail DOT com>
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Subject:	Re: How to build gcc to support wchar_t and wstring on Cygwin
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Absolutely.  c++config.h which control the definition of _GLIBCXX_USE_WCHAR_T
is part of libstdc++.
c++config.h locates in a architecture related directory like
c++/4.4.0/i686-pc-cygwin/bits. So it must be a dynamically generated file
during build process. I found c++config in fresh source code, that probably
is used as a template to generate c++config.h. According what the build
process decide not to define
_GLIBCXX_USE_WCHAR_T? Just the os type? Is there any other detection? I
guess no. When I built icu, the configure messages shows 
checking wchar.h usability  ..... yes
checking wchar.h presence ..... yes
checking for wchar_t  ... yes
checking size of wchar_t   2

Maybe icu use it's own wchar_t.  Does anyone know these?



Dave Korn-6 wrote:
> 
> Mark J. Reed wrote:
>> On Thu, Jun 25, 2009 at 1:10 PM, Match Point
>>> wstring is not supported on my Cygwin 1.5.25. When I  declare a
>>> wstring variable my g++ 3.4.4 complains wstring is undeclared. After
>>> reading some posted message I figured out wstring is not supported on
>>> Cygwin 1.5 or even 1.7. To fix this I have to rebuild entire gcc.
>> 
>> No, to fix that you have to convince the newlib developers to add
>> wstring support to newlib.
>> 
>>> _GLIBCXX_USE_WCHAR_T is still not defined.
>> 
>> Cygwin does not use glibc.
> 
>   Whoah!  Hang on there!  Cygwin does indeed use newlib, not glibc; but
> GLIBCXX_ #defines in GCC don't relate to glibc, they relate to
> libstdc++-v3.
> 
>     cheers,
>       DaveK
> 
> 
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