[build2] Recommended way to override build2 configuration CLI arguments

[Matthew Krupcale]

On Thu, Mar 14, 2019 at 2:01 PM Boris Kolpackov <boris at codesynthesis.com> wrote:
>
> I went ahead and implemented the whole thing, which means now not only
> can we do:
>
> $ b config.cxx.coptions=-O3 config.cxx.coptions=-O0
>
> But also:
>
> $ b config.cxx.coptions=-O3 config.cxx.coptions+=-g
>

Oh nice work--I'm sure that will be useful for similar use cases (i.e.
adding to default/macro values).

> We are aiming to make a release early next week

Okay, cool, looking forward to it. I also have some
comments/improvements regarding the PostScript and PDF documentation I
will send in another email.

> so if you could give this a try before then, that would be great.

I tested this with CLI using my macro, and it works now[1].

> The latest staged toolchain is probably the easiest way to test this
> since the changes are somewhat substantial and are spread over several
> commits. Alternatively, you can try to apply them to 0.9.0:

I have a spec file which can work with arbitrary commits, but it's a
little outdated, and it was just easier to apply the patches to 0.9.0
in my current spec file.

Best,
Matthew

[1] https://copr-be.cloud.fedoraproject.org/results/mkrupcale/build2/fedora-29-x86_64/00868512-cli/build.log.gz