Re: C++17 skeleton with move semantics and std::variant

[Frank Heckenbach]

Hans Åberg wrote:

> > On 8 Apr 2018, at 23:05, Frank Heckenbach <address@hidden> wrote:
> 
> > - Uses std::variant (C++17) instead of Bison's own variant
> >  implementation.
> > 
> >  If you don't have C++17 support yet, you can use an alternative
> >  variant implementation such as https://github.com/mpark/variant .
> >  Boost.Variant might also work; I have not tried it.
> 
> Akim Demaille gave two motivations on not using this: avoiding the
> external dependency, and the overhead of storing the type. I think
> that the C++17 variants may have the latter, but it is not so
> important on modern computers.

Yes, they do, and it's needed. That's exactly what fixes the
problems with $<type> -- the type must be stored somewhere.

Not storing the type seems a nifty idea with Bison which knows about
the type most of the time, but it breaks down just there.

> But, anyway, GCC7 supports C++17.

Yes, and I've also tested it with gcc-6 with mpark's variant.

Regards,
Frank