AW: Re: Bug? access to copy-constructor for operator= needed in gcc-4.0

AW: Re: Bug? access to copy-constructor for operator= needed in gcc-4.0

[debian]

>
>Martin Kittel wrote:
>
>>         // works fine
>>         A a;
>>         m_a = a;
>
>>         // needs access to copy-constructor, why?
>>         m_a = A();
>
>This is about reference binding of parameters.  8.5.3 says how references are initialized.  in particular, 'a' is a non-temporary lvalue so the reference can be bound directly to it -- no copy ctor required.
>

I am not convinced. 8.5.3 is about reference initialization, while m_a is neither a reference nor are we talking about initialization here. To me, this is just plain assignment.

So, I'd still say A() is plain construction of a temporary, and then according to 5.17 the copy assignment operator of m_a should be called (it is important here that we are not talking about initialization).

Best wishes,

Martin.

Re: AW: Re: Bug? access to copy-constructor for operator= needed in gcc-4.0

[Nathan Sidwell]

debian@martin-kittel.de wrote:

> I am not convinced. 8.5.3 is about reference initialization, while m_a is neither a reference nor are we talking about initialization here. To me, this is just plain assignment.

the reference binding occurs in the call to the copy assignment operator.

> So, I'd still say A() is plain construction of a temporary, and then according to 5.17 the copy assignment operator of m_a should be called (it is important here that we are not talking about initialization).

you are ignoring the binding of the copy asignment operator's arguments.

nathan

-- 
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Re: AW: Re: Bug? access to copy-constructor for operator= needed in gcc-4.0

[Martin Kittel]

Nathan Sidwell <nathan <at> codesourcery.com> writes:

> 
> 
> the reference binding occurs in the call to the copy assignment operator.
> 
Of course - I missed that one completely. So while quite counter-intuitive, I
agree with you now.

Thanks for the clarification.

Best wishes,

Martin.

Re: AW: Re: Bug? access to copy-constructor for operator= needed in gcc-4.0

[corey taylor]

12.2 of the C++ specification provides more details on the use of
temporary objects especially in this instance.

8.5.3 can be one of the hardest to follow sections :)

corey

On 6/13/05, Martin Kittel <debian@martin-kittel.de> wrote:
> Nathan Sidwell <nathan <at> codesourcery.com> writes:
> 
> >
> >
> > the reference binding occurs in the call to the copy assignment operator.
> >
> Of course - I missed that one completely. So while quite counter-intuitive, I
> agree with you now.
> 
> Thanks for the clarification.
> 
> Best wishes,
> 
> Martin.
> 
>