Re: [boost] [function] Placement new warnings from gcc 6

Subject: Re: [boost] [function] Placement new warnings from gcc 6
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2016-04-02 10:34:30

On 2016-04-02 16:08, Andrey Semashev wrote:
> On 2016-04-02 15:45, Peter Dimov wrote:
>> Andrey Semashev wrote:
>>
>>> Thanks. I've made a patch with a similar idea:
>>>
>>> https://github.com/boostorg/function/pull/9
>>
>> This works, although the following alternative:
>>
>> template<class T> union function_buffer_
>> {
>>    // as before
>>    mutable T data;
>> };
>>
>> size_t const function_buffer_size = sizeof(function_buffer_<char>);
>>
>> typedef function_buffer_<char[function_buffer_size]> function_buffer;
>>
>> seems slightly more maintainable as it doesn't perform the size
>> computation separately.
>
> That instantiates the template twice, maybe it'll affect compile times.
> Also, I'm a bit cautious about using an array type in template
> parameters - maybe it'll cause trouble on ancient compilers?
>
> I guess, I could extract all members other than 'data' to a separate
> union and then:
>
>   union function_buffer
>   {
>     mutable function_buffer_members m;
>     mutable char data[sizeof(function_buffer_members)];
>   };
>
> This would require more modifications to the code though.

Ok, I updated my pull request to implement the above version.