Re: [boost] [config] Rethinking feature macros?

Subject: Re: [boost] [config] Rethinking feature macros?
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2017-11-06 16:37:54

On November 6, 2017 7:13:06 PM Peter Dimov via Boost 
<boost_at_[hidden]> wrote:

> Andrey Semashev wrote:
>
>> > You're refuting your own argument, because if g++-15 would need 200
>> > positive macros compared to g++-7's 100, g++-7 would need 100 negative
>> > macros.
>>
>> g++-7 will be out of wide use by then, so it doesn't matter.
>
> That's not true on at least three levels.

Why?

>> > The good thing about positive macros is that an old compiler never needs
>> > maintenance. With negative macros you have to keep adding them to it.
>>
>> That is not more maintenance than adding positive macros for newer
>> compilers.
>
> It is. Maintaining the new compilers is constant regardless of the macro
> type, and maintaining the old compilers is only required for negative
> macros.

I don't see how. You have to add new macros as they come with new C++ 
versions or someone requests them. You have to test them. All this is the 
same amount of work regardless of whether the macro is positive or negative.