Re: [boost] [Thread] possible bug in Move emulation "portable interface"

Subject: Re: [boost] [Thread] possible bug in Move emulation "portable interface"
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2013-09-07 04:00:26

Le 04/09/13 07:53, Gavin Lambert a écrit :
> I tried submitting this via Trac but for some reason it was convinced 
> that my bug report contained spam, while refusing to tell me what part 
> it was objecting to, and also refusing to give me a captcha or 
> anything to convince it otherwise.
>
> Anyways:
>
> Bug 1: the Boost.Thread documentation and release history indicate 
> that BOOST_THREAD_VERSION==3 is the default since v1.52.  As far as I 
> can tell this has never been true in any released version; the latest 
> code still has ==2.  (I found a thread in boost-devel that was 
> debating consequences of making breaking changes by default, which I 
> assume is why this change was not actually made; but the docs need 
> correcting.)
This was my intention, but this was not possible as the Boost community 
didn't accept the breaking changes.
Please could you point me where in the documentation this misinformation 
is still there?
>
> Bug 2: when writing code using the Boost.Thread "Portable Interface" 
> for move support/emulation, it recommends using the 
> BOOST_THREAD_DCL_MOVABLE_BEG macro to "avoid conflicts with 
> Boost.Move".  However regardless of C++11 or not or the 
> BOOST_THREAD_VERSION it defines a template specialisation in a way 
> that assumes that it is called only from "namespace boost". 
You are right. The macro must be used inside the boost namesapce.
> As this usage is unlikely for any code outside the boost library 
> itself, I think this is a bug.
Well, as the constraint is not on the documentation, I consider it a bug.
>
> namespace user
> {
>    template<typename T>
>    class test
>    {
>    public:
>        BOOST_THREAD_COPYABLE_AND_MOVABLE(test)
>
>        test() {}
>        test(const test&) {}
>        test& operator=(BOOST_COPY_ASSIGN_REF(test) o) { return *this; }
>        test(BOOST_THREAD_RV_REF(test) o) {}
>        test& operator=(BOOST_THREAD_RV_REF(test) o) { return *this; }
>    };
>    BOOST_THREAD_DCL_MOVABLE_BEG(T) test<T> BOOST_THREAD_DCL_MOVABLE_END }
>
> The above code will not compile.  It does compile if the DCL define is 
> moved into a "namespace boost" block, but I do not regard this as an 
> acceptable solution.
>
> Suggested fix is to explicitly specify the namespace in the macro, eg. 
> replace "enable_move_utility_emulation" with 
> "::boost::enable_move_utility_emulation".
>
>
>
Humm, I don't know if this is correct. In any case I didn't know that we 
could specialize templates this way. Could some one confirm this kind of 
specializations is portable?

Best,
Vicente