Re: [Boost-users] serialization: BOOST_STATIC_WARNING

Subject: Re: [Boost-users] serialization: BOOST_STATIC_WARNING
From: Travis Gockel (travis_at_[hidden])
Date: 2011-05-25 15:49:35

The problem can be reproduced even more simply:

BOOST_STATIC_WARNING(false);

does not produce a warning on my machine.

If I make my own (not as versatile) version, which mimics the way Boost
actually does it without all the MPL stuff, it works:

namespace detail
{
    template <typename TIntegralContant>
    inline void test_warning(const TIntegralContant&)
    {
        static_cast<void>(1 / TIntegralContant::value);
    }
}

#define MY_STATIC_WARNING(value_) \
    ::detail::test_warning(::boost::integral_constant<bool, value_ >())

So it isn't that g++ won't emit a warning for that error, it just seems to
get lost somewhere.

On Wed, May 25, 2011 at 1:16 PM, Ovanes Markarian <om_boost_at_[hidden]>wrote:

>
>
> On Wed, May 25, 2011 at 7:09 PM, Travis Gockel <travis_at_[hidden]>wrote:
>
>> I've recently had some trouble with C++'s implicit casting, so I'm looking
>> for a way to warn people if somebody attempts to assign an int32_t to a
>> uint64_t or whatever.  BOOST_STATIC_ASSERT would work wonders for this,
>> except that the code base I'm working with is quite large and relies on a
>> lot of implicit casting, so immediately breaking everything with assertions
>> is unrealistic.
>>
>> It looks like BOOST_STATIC_WARNING (
>> http://www.boost.org/doc/libs/1_46_1/libs/serialization/doc/static_warning.html)
>> would be ideal for me, however, I cannot get it to actually emit a warning.
>>  I have attached a quick example of what I am looking for, but it
>> essentially boils down to this not doing anything:
>>
>>         typedef boost::is_same<int64_t, int32_t> same_type;
>>         BOOST_STATIC_WARNING(same_type::value);
>>
>> My compiler is g++ 4.4.3 with --std=c++0x -Wall -Wextra.
>>
>> Thanks!
>>
>
> Hello Travis,
>
> unfortunately I have no boost 1.46 by the hand, but as far as I understand
> int64_t and int32_t are different type and should not result in value equals
> true. What happens if you produce non-convertible types like:
>
> template<class T> identity{}; //you can also use mpl::identity
>
> typedef boost::is_same<identity<int64_t>, identity<int32_t> > same_type;
>
> BOOST_STATIC_WARNING(same_type::value);
>
>
> With Kind Regards,
> Ovanes
>
>
>
>
>
> _______________________________________________
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> Boost-users_at_[hidden]
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>

-- 
- Travis Gockel