[Boost-users] BOOST_CHECK_EQUAL_COLLECTIONS fails to compile when comparing vector<wstring>

Subject: [Boost-users] BOOST_CHECK_EQUAL_COLLECTIONS fails to compile when comparing vector<wstring>
From: Mauricio Gomes (mgpensar_at_[hidden])
Date: 2009-04-13 21:56:57

Hi,
I am using Windows XP, boost 1.38 and mingw 3.4.5 (Code::Blocks IDE).
I cannot compile BOOST_CHECK_EQUAL_COLLECTIONS when using wstring. See
below:

#define CHECK_EQUAL_COLLECTIONS(L, R)         \
  BOOST_CHECK_EQUAL_COLLECTIONS((L).begin (), (L).end (), (R).begin (),
(R).end ())

vector<string > v1;
vector<wstring> v2;

CHECK_EQUAL_COLLECTIONS(v1, v1); // this compiles fine.
CHECK_EQUAL_COLLECTIONS(v2, v2); // this gives me the error listed below (at
the end).

Searching for a solution I've found this:
http://lists.boost.org/boost-users/2005/09/13720.php
And in fact, adding the code below solves it.
namespace std
{
    ostream& operator << (ostream& ostr, wstring const& str)
    {
       ostr << boost::lexical_cast<wstring>(str);
       return ostr;
    }
}

However this seems somewhat clumsy to me.
I do not like the idea of doing a cast like this that obviously can fail if
the wstring has a wide char that cannot be mapped to char properly. And it
seems inappropriate to require the user to define such a thing.
Is there a better way of solving this ? Can anything be done in the unit
test framework itself to solve this in a better way ?

I am a beginner with template metaprogramming so I ask the experts here to
tell me if there is a better way or if that's the way it is and nothing can
be done.

Thank you for your attention !
Mauricio.

c:\boost_1_38_0\boost\test\utils\wrap_stringstream.hpp||In function
`boost::basic_wrap_stringstream<CharT>&
boost::operator<<(boost::basic_wrap_stringstream<CharT>&, const T&) [with
CharT = char, T = std::basic_string<wchar_t, std::char_traits<wchar_t>,
std::allocator<wchar_t> >]':|
c:\boost_1_38_0\boost\test\test_tools.hpp|641|instantiated from
`boost::test_tools::predicate_result
boost::test_tools::tt_detail::equal_coll_impl(Left, Left, Right, Right)
[with Left = __gnu_cxx::__normal_iterator<std::wstring*,
std::vector<std::wstring, std::allocator<std::wstring> > >, Right =
__gnu_cxx::__normal_iterator<std::wstring*, std::vector<std::wstring,
std::allocator<std::wstring> > >]'|
C:\projects\cpplib\source\test\string_util_test.cpp|71|instantiated from
here|
c:\boost_1_38_0\boost\test\utils\wrap_stringstream.hpp|66|error: no match
for 'operator<<' in '(+targ)->boost::basic_wrap_stringstream<CharT>::stream
[with CharT = char]() << t'|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|63|note:
candidates are: std::basic_ostream<_CharT, _Traits>&
std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT,
_Traits>&(*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char,
_Traits = std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|74|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(std::basic_ios<_CharT,
_Traits>&(*)(std::basic_ios<_CharT, _Traits>&)) [with _CharT = char, _Traits
= std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|86|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(std::ios_base&(*)(std::ios_base&)) [with _CharT = char,
_Traits = std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|121|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|155|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|98|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(bool) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|178|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(short int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|189|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|193|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|204|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|179|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long long int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|214|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|238|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(double) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|219|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(float) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|261|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long double) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|284|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(const void*) [with _CharT = char, _Traits =
std::char_traits<char>]|
C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|307|note:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(std::basic_streambuf<_CharT, _Traits>*) [with _CharT =
char, _Traits = std::char_traits<char>]|
c:\boost_1_38_0\boost\test\utils\xml_printer.hpp|103|note:
std::ostream& boost::unit_test::operator<<(const
boost::unit_test::custom_printer<boost::unit_test::pcdata>&,
boost::unit_test::const_string)|
c:\boost_1_38_0\boost\test\utils\lazy_ostream.hpp|40|note:
std::ostream& boost::unit_test::operator<<(std::ostream&, const
boost::unit_test::lazy_ostream&)|
||=== Build finished: 1 errors, 0 warnings ===|

-- 
Mauricio Gomes
Pensar Digital
55-11-8319-9610 (Brazil - mobile)