Re: Implementing p0515 - spaceship operator

[Jason Merrill <jason at redhat dot com>]

On Mon, Jan 8, 2018 at 4:07 PM, Tim van Deurzen <tim@kompiler.org> wrote:
> I've been spending some time the past few weeks implementing p0515r2,
> i.e. the proposal for consistent comparisons for C++ (aka the spaceship
> operator).

Great!

> I've received some very valuable help on the IRC channel, but
> I'm still a little bit stuck. Note, I'm completely new to the GCC
> codebase and am very much still getting oriented.
>
> Following advice from some of the people in IRC channel I implemented
> parsing the new token in libcpp and I seem to be successfully parsing it
> and creating a new AST node. As this feature is not in the C++ standard
> yet, I wanted to add a command line flag to enable usage of the new
> operator and ignoring it otherwise. I managed to get cc1plus to accept
> the parameter, but it seems that when I invoke my own g++ binary with
> that parameter, it complains about unknown parameters.
>
> I'm perfectly happy to dig further on my own, but I get the feeling I'm
> missing some documentation / resource somewhere that might help me out.
> Is there some documentation about adding and passing around parameters
> that will be used both in libcpp and the C++ front-end? What would be
> the best place to look to learn more about how part of GCC this is
> structured? I want to make sure I go about this correctly.

There's a gccint.info documentation file, the Options node seems like
what you're looking for.  You will want to add a new option to
c-family/c.opt.

> If this is the wrong place to ask for help, please redirect me, so that
> I don't unnecessarily spam the wrong mailing list :-).

I'm not sure whether gcc@ or gcc-patches@ is better for this sort of
question (without a patch).  I tend to miss a lot that goes by on the
mailing list, so CCing me directly about C++ changes is also helpful.

Jason