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

Subject: Re: [boost] [iterator][type_traits] A test is failing with gcc in c++03mode
From: John Maddock (jz.maddock_at_[hidden])
Date: 2016-12-17 13:19:35

On 17/12/2016 16:45, Peter Dimov wrote:
> Edward Diener wrote:
>> 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 ?
>
> References to references were invalid in C++98, but were made 
> conditionally valid in C++03 by
>
> http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#106
>
> However, __is_abstract is nonstandard, so who knows what it does. It 
> might be worth trying -std=gnu++03 instead of -std=c++03.

I think the issue here is that you are calling 
__is_abstract(malformed_type) - so when the compiler instantiates 
std::pair<int&, std::string&> to see if it's abstract or not the error 
gets generated.  But I'm not sure that helps ;)

John.