Re: [boost] [utility] value_init warning

From: Paul A Bristow (pbristow_at_[hidden])
Date: 2007-10-15 10:23:22

>-----Original Message-----
>From: boost-bounces_at_[hidden] 
>[mailto:boost-bounces_at_[hidden]] On Behalf Of Niels 
>Dekker - mail address until 2008-12-31
>Sent: 15 October 2007 13:00
>To: boost_at_[hidden]
>Subject: Re: [boost] [utility] value_init warning
>
>Gennadiy Rozental wrote:
>> I am building trunk version of Boost.Test with msvc 8.0 and
>> see following warning:
>> ..\..\..\boost/utility/value_init.hpp(73) : warning C4345:
>>   behavior change: an object of POD type constructed with
>>   an initializer of the form () will be default-initialized
>
>I guess the warning is caused by an MSVC-specific workaround that I 
>committed to trunk/boost/utility/value_init.hpp, September 7, [39157].
>My apologizes!
>
>The MSVC warning is about the following line of code:
>  new (&x) T();
>
>This line of code looks perfectly fine to me!  The warning 
>just tells us 
>that when T is a POD struct, the newly created object will be 
>initialized. 
>As it should!  Note that MSVC 7.1 produces the very same 
>warning, so it 
>isn't really a "behavior change" of MSVC 8.0.
>
>> Can we do something about it?
>
>Do you have a suggestion?  #pragma warning(disable: 4345)?

Don't forget to push'n'pop the warning level - in case any user finds this warning informative.

#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable: 4345)
#endif
...

#ifdef BOOST_MSVC
#pragma warning(pop)
#endif

---
Paul A Bristow
Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB
[phone] & SMS, Mobile [phone] & SMS
pbristow_at_[hidden]