libstdc++ of g++ 3.4.x: std::swap and std::auto_ptr causes compilation errors

Vinzenz Feenstra evilissimo@web.de
Tue Nov 16 10:54:00 GMT 2004


Paolo Carlini wrote:

> Vinzenz Feenstra wrote:
>
>> std::swap of 3.4
>>  template<typename _Tp>
>>    inline void
>>    swap(_Tp& __a, _Tp& __b)
>>    {
>>      // concept requirements
>>      __glibcpp_function_requires(_SGIAssignableConcept<_Tp>)
>>          const _Tp __tmp = __a; // <-- this is the problem in my opinion
>>      __a = __b;
>>      __b = __tmp;
>>    }
>
>
> Yes, you are right that this is the ""problem"", in the sense that, being
> auto_ptr not Assignable, later, in __b = __tmp, its assignment operator
> wants a *non* constant reference. We (I) could revert the change which
> const-ified, correctly, the temporary, but the fundamental problem of
> your testcase would remain the same: try compiling it passing,
>
>    -D_GLIBCXX_CONCEPT_CHECKS
>
> on 3.4 or
>
>    -D_GLIBCPP_CONCEPT_CHECKS
>
> on 3.3 (this actually enables the concept check encoded in the
> __glibcpp_function_requires line)
>
> Paolo.

hmm

I don't understand, why I have to set it? This is strange to me, too. 
Shouldn't it be setted automatically?
I mean this is confusing me abit.

Ok Thanks for explaining.

BR

Vinzenz



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