Re: [boost] Removing support for old compilers

Subject: Re: [boost] Removing support for old compilers
From: Stephen Kelly (steveire_at_[hidden])
Date: 2013-10-13 16:06:40

On 10/13/2013 09:52 PM, Peter Dimov wrote:
> Stephen Kelly wrote:
>> My changes amount to removal of definitions of some macros in
>> boost/config, followed by removal of newly-dead code.
>
> That's not quite true, Stephen.
>
> Here are a few examples of changes that do not remove any dead code:
>
> -#if defined(BOOST_NO_TEMPLATED_IOSTREAMS) || ( defined(__GNUC__) &&
> (__GNUC__ < 3) )
> +#if ( defined(__GNUC__) &&  (__GNUC__ < 3) )
>
> -- 
>
> -#elif defined( _MSC_VER ) && _MSC_VER >= 1310
> +#elif defined( _MSC_VER )
>
> -- 
>
> -#if defined(_MSC_VER) && _MSC_VER >= 1310 && ( defined(_M_IX86) ||
> defined(_M_X64) )
> +#if defined(_MSC_VER) && ( defined(_M_IX86) || defined(_M_X64) )
>
> -- 
>
> -#if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
> ...
> -#endif
>
> -- 
>
> -#if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined(
> BOOST_NO_SFINAE )
> +#if !defined( BOOST_NO_SFINAE )
>

I consider all of the above to be dead code removal. It's ok that you
don't see it the same way.

> Now, you'd say that in some of these cases, this is just the first
> step of a process that will eventually result in the removal of dead
> code. Maybe so. But in the meantime, we're left with an #ifdef that
> makes much less sense than the original, which was generally
> self-documenting.

We also have a revision control system.

> When I see
>
> #if defined(BOOST_NO_TEMPLATED_IOSTREAMS) || ( defined(__GNUC__) &&
> (__GNUC__ < 3) )
>
> I know that the following is a workaround for the lack of templated
> iostreams, and that for some (admittedly lost in time) reason, g++ 2.x
> lacks templated iostreams but does not define the config macro.
> Without the first portion, this information is no longer present.

... in the source code. It is still in the revision control system,
which has logs which are file-specific and a 'blame' feature which is
line-specific.

>
> Few people would object to actual removal of dead code sections such as
>
> #if defined(THIS) || defined(THAT)
>
> ...
>
> #endif
>
> when we know that neither THIS nor THAT will ever be defined (there
> are some rare exceptions to that). Fiddling with the ifdef conditions
> is another story.

I just don't agree with your mail.

Thanks,

Steve.