Re: libstdc++: compiling with iostream header: error: unknown type name 'char_traits'

[Nobin Mathew <nobin dot mathew at gmail dot com>]

On Sun, Jun 20, 2010 at 11:03 AM, Nobin Mathew <nobin.mathew@gmail.com> wrote:
> Hi,
>
> I am having a problem with libstdc++ headers, I am having a simple
> application which uses iostream library. In order to parse it I am
> using clang library application.
>
> For that I am getting an error like this
>
> In file included from /home/nmathew/Desktop/algorithms/array.cpp:1:
> In file included from /usr/include/c++/4.4.3/iostream:39:
> In file included from /usr/include/c++/4.4.3/ostream:39:
> In file included from /usr/include/c++/4.4.3/ios:38:
> In file included from /usr/include/c++/4.4.3/iosfwd:40:
> /usr/include/c++/4.4.3/bits/stringfwd.h:49:48: error: unknown type
> name 'char_traits'
>
>
> If I use g++ it compiles properly.
>
>
> My include search directories are ? below:
>
> #include "..." search starts here:
> #include <...> search starts here:
> ?/usr/include/linux
> ?/usr/lib/gcc/i686-redhat-linux/4.4.3/include
> ?/usr/include/c++/4.4.3
> ?/usr/include/c++/4.4.3/backward
> ?/usr/include/c++/4.4.3/i686-redhat-linux
> ?/usr/local/include
> ?/usr/include
> End of search list.

and char_traits.h is in /usr/include/c++/4.4.3/bits/
>
> When I looked at the header source, this is the order of inclusion
> iostream->ostream->ios->iosfwd
>
> iosfwd uses uses char_traits but bits/char_traits.h is included after
> iosfwd in ios header
>
> From /usr/include/c++/4.4.3/ios
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> #ifndef _GLIBCXX_IOS
> #define _GLIBCXX_IOS 1
>
> #pragma GCC system_header
>
> #include <iosfwd>
> #include <exception> ? ? ? ? ? ?// For ios_base::failure
> #include <bits/char_traits.h> ? // For char_traits, streamoff, streamsize, fpos
> #include <bits/localefwd.h> ? ? // For class locale
> #include <bits/ios_base.h> ? ? ?// For ios_base declarations.
> #include <streambuf>
> #include <bits/basic_ios.h>
>
> #endif ?/* _GLIBCXX_IOS */
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> From /usr/include/c++/4.4.3/iosfwd
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> #ifndef _GLIBCXX_IOSFWD
> #define _GLIBCXX_IOSFWD 1
>
> #pragma GCC system_header
>
> #include <bits/c++config.h>
> #include <bits/stringfwd.h> ? ? // For string forward declarations.
> #include <bits/postypes.h>
>
> _GLIBCXX_BEGIN_NAMESPACE(std)
>
> ?template<typename _CharT, typename _Traits = char_traits<_CharT> >
> ? ?class basic_ios;
>
> ?template<typename _CharT, typename _Traits = char_traits<_CharT> >
> ? ?class basic_streambuf;
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> How this works and what is the use of bits/c++config.h file.
>
> Please help even if this is a dump question, I am new to the land of c++.

I am using Fedora 12,  where
[nmathew@Alchemist cppscope]$ gcc -v
Using built-in specs.
Target: i686-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap
--enable-shared --enable-threads=posix --enable-checking=release
--with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-gnu-unique-object
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada
--enable-java-awt=gtk --disable-dssi --enable-plugin
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre
--enable-libgcj-multifile --enable-java-maintainer-mode
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic
--with-arch=i686 --build=i686-redhat-linux
Thread model: posix
gcc version 4.4.3 20100127 (Red Hat 4.4.3-4) (GCC)

>
> Thanks
> Nobin
>