Re: [boost] [config] RFC PR 82

Subject: Re: [boost] [config] RFC PR 82
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2015-11-24 16:03:14

On 2015-11-24 23:54, Agustín K-ballo Bergé wrote:
> On 11/24/2015 5:20 PM, Andrey Semashev wrote:
>>>> Ditto BOOST_HAS_UNION_TYPE_PUNNING_TRICK (doesn't any compiler support
>>>> this?).
>>>
>>> 'I'm all with you on this one' but since 'it is not in the standard'
>>> language purists will probably complain if it is used unconditionally...
>>
>> To some extent this is guaranteed by [class.union]/1 in C++11.
>
> No, it isn't.

Why? Reading different members of the standard layout union within the 
common initial sequence is enough to implement a bitwise_cast.