Re: [boost] [config] Positive feature macros, r2

Subject: Re: [boost] [config] Positive feature macros, r2
From: John Maddock (jz.maddock_at_[hidden])
Date: 2018-01-25 18:01:05

>> TL;DR we should switch to positive feature macros in Boost.Config, 
>> and delaying this switch just accumulates more unnecessary code in 
>> Boost.Config.
>
> My opinion hasn't changed since the last discussion - if we move to 
> positive macros then please convert all existing macros as well. I 
> wouldn't want to remember which one is positive or negative.
>

+1 on that.

I've been mostly silent on this because:

* Other folks have expressed what I feel as well (but I'm notoriously 
slow to embrace change, so treat that with a pinch of salt).
* The number of new macros has slowed very significantly in recent years.
* The number of actively developed compilers is very much lower than in 
the past.
* I see no great gain for *users* of the library.
* We currently separate standardized features which are all BOOST_NO_* 
and vendor extensions which are all BOOST_HAS_*.

For compilers that are effectively "dead", we could just add a catch all 
macro:

#define BOOST_OBSOLETE_COMPILER year

and then set all macros past "year" in suffix.hpp, so if we had

#define BOOST_OBSOLETE_COMPILER 2011

Then set all BOOST_NO_CXX11_* macros and later in suffix.hpp and job done.

John.

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