--- In Boost-Users@yahoogroups.com, "Ben Hutchings" > I compiled almost the exact same code:

#include #include <map> #include <utility>

typedef

std::basic_string

...

...

t;

int main() { std::map > > m; }

with VC++ 7.0 and Boost 1.29, and got no warnings or errors at all.

Ah, yes, that works for me, too (no warning, either), but try adding a line of code that actually uses the map, like this: m["abc"] = "def"; and you get the following cascade of errors: stupid.cpp C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)' : could not deduce template argument for 'const std::_Tree<_Traits> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xtree(1170) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(138) : while compiling class-template member function 'bool std::less<_Ty>::operator ()(const _Ty &,const _Ty &) const' with [ _Ty=t ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\map(67) : see reference to class template instantiation 'std::less<_Ty>' being compiled with [ _Ty=t ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xtree(23) : see reference to class template instantiation 'std::_Tmap_traits<_Kty,_Ty,_Pr,_Alloc,_Mfl>' being compiled with [ _Kty=t, _Ty=t, _Pr=std::less<t>, _Alloc=boost::pool_allocator>, _Mfl=false ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xtree(65) : see reference to class template instantiation 'std::_Tree_nod<_Traits>' being compiled with [ _Traits=std::_Tmap_traits>,false> ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xtree(87) : see reference to class template instantiation 'std::_Tree_ptr<_Traits>' being compiled with [ _Traits=std::_Tmap_traits>,false> ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xtree(105) : see reference to class template instantiation 'std::_Tree_val<_Traits>' being compiled with [ _Traits=std::_Tmap_traits>,false> ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\map(77) : see reference to class template instantiation 'std::_Tree<_Traits>' being compiled with [ _Traits=std::_Tmap_traits>,false> ] stupid.cpp(12) : see reference to class template instantiation 'std::map<_Kty,_Ty,_Pr,_Alloc>' being compiled with [ _Kty=t, _Ty=t, _Pr=std::less<t>, _Alloc=boost::pool_allocator> ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)' : could not deduce template argument for 'const std::_Tree<_Traits> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xtree(1170) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)' : could not deduce template argument for 'const std::_Tree<_Traits> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xtree(1170) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::reverse_iterator<_RanIt> &,const std::reverse_iterator<_RanIt> &)' : could not deduce template argument for 'const std::reverse_iterator<_RanIt> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xutility(655) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::reverse_iterator<_RanIt> &,const std::reverse_iterator<_RanIt> &)' : could not deduce template argument for 'const std::reverse_iterator<_RanIt> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xutility(655) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::reverse_iterator<_RanIt> &,const std::reverse_iterator<_RanIt> &)' : could not deduce template argument for 'const std::reverse_iterator<_RanIt> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\xutility(655) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::pair<_Ty1,_Ty2> &,const std::pair<_Ty1,_Ty2> &)' : could not deduce template argument for 'const std::pair<_Ty1,_Ty2> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\utility(73) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::pair<_Ty1,_Ty2> &,const std::pair<_Ty1,_Ty2> &)' : could not deduce template argument for 'const std::pair<_Ty1,_Ty2> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\utility(73) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2784: 'bool std::operator <(const std::pair<_Ty1,_Ty2> &,const std::pair<_Ty1,_Ty2> &)' : could not deduce template argument for 'const std::pair<_Ty1,_Ty2> &' from 'const t' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\utility(73) : see declaration of 'std::operator`<'' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7 \include\functional(139) : error C2676: binary '<' : 'const t' does not define this operator or a conversion to a type acceptable to the predefined operator

I don't have VC++ 7.1 to hand, but I would be surprised if it broke anything that worked in 7.0.