[boost] [iterator][type_traits] A test is failing with gcc in c++03 mode

Subject: [boost] [iterator][type_traits] A test is failing with gcc in c++03 mode
From: Edward Diener (eldiener_at_[hidden])
Date: 2016-12-16 23:02:47

The zip_iterator_test_std_pair is failing with gcc in c++-03 mode. The 
problem reduces viqa Boost type traits to the fact that in gcc c++03 
mode the expression:

__is_abstract(std::pair<int&, std::string&>)

where __is_abstract is a compiler intrinsic, gives an error of:

error: forming reference to reference type 
'std::__cxx11::basic_string<char>&'
        pair(const _T1& __a, const _T2& __b)
        ^~~~

Is this a valid error according to the C++ 2003 standard ?

The test works in c++11 or c++14 mode.