Subject: Re: [boost] [config] Rethinking feature macros?
From: Peter Dimov (lists_at_[hidden])
Date: 2017-11-06 17:02:35
Andrey Semashev wrote:
> >> g++-7 will be out of wide use by then, so it doesn't matter.
> > That's not true on at least three levels.
1. C++17 still matters even if g++-15 -std=c++17 is used instead of
2. g++-7 will not be out of wide use as today we still have to care about
3. Even if a compiler is out of wide use, we still maintain Config for it.
> >> > 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
On an old compiler, you don't need to add new positive macros, so there's
less work to do.
On a new compiler, you either add the positive macro to -std=c++17 or add
the negative macro to -std=c++14 and below, so the work is the same.
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