Re: C++: add -std={c,gnu}++{current,future}

[Jason Merrill <jason@redhat.com>]

On 7/13/22 15:29, Nathan Sidwell wrote:
> Inspired by a user question.  Jason, thoughts?
> 
> Since C++ is such a moving target, Microsoft have /std:c++latest
> (AFAICT clang does not), to select the currently implemented version
> of the working paper.  But the use of 'std:latest' is somewhat
> ambiguous -- the current std is C++20 -- that's the latest std, the
> next std will more than likely but not necessarily be C++23.  So this
> adds:
> 
>    -std=c++current -- the current std (c++20)
>    -std=c++future -- the working paper (c++2b)
> 
> also adds gnu++current and gnu++future to select the gnu-extended
> variants.

I like this direction.

I imagine people using these to mean roughly beta and alpha, respectively.

Perhaps we also want -std=c++stable, which would currently be equivalent 
to the default (c++17) but might not always be.

Jason