From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yann E. MORIN <yann.morin.1998@free.fr>
Date: Sun, 29 Nov 2015 22:14:48 +0100
Subject: [Buildroot] [PATCH 2/3] Config.in: add symbols for
 BR2_HOST_GCC_AT_LEAST_X_Y
In-Reply-To: <565B665B.9050304@mind.be>
References: <1448147919-5463-1-git-send-email-arnout@mind.be>
 <1448147919-5463-2-git-send-email-arnout@mind.be>
 <20151129174805.GC3630@free.fr> <565B665B.9050304@mind.be>
Message-ID: <20151129211448.GK3630@free.fr>
List-Id: <buildroot.busybox.net>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: buildroot@busybox.net

Arnout, All,

On 2015-11-29 21:55 +0100, Arnout Vandecappelle spake thusly:
> On 29-11-15 18:48, Yann E. MORIN wrote:
> > Arnout, All,
> > 
> > On 2015-11-22 00:18 +0100, Arnout Vandecappelle (Essensium/Mind) spake thusly:
> >> Some host packages need a recent gcc version. Add symbols to Config.in
> >> to specify the HOSTCC version. The values are passed through the
> >> environment, and this environment is generated in a new support script.
> > 
> > I really don't like this...
> 
>  I originally had it as a make fragment :-P
> 
> > 
> > Maybe it is a good candidate for a generated kconfig snippet, instead of
> > this generated-environment oddity?
> 
>  I never thought of that, it would be a possibility. If I would have time :-)
> I'd have a go at it.

I already have all that is needed to generate a kconfig fragment, in my
multi br2-external series.

It was meant only as a mean to add the generated Config.in that
aggregates all the br2-external entries, but otherwise adds all the
dependencies in the Makefile to ensure the fragment is created before we
run any kconfig program.

So, if you could review those patches, we can get them early (if not the
complete series) so all you'd have is to write the kconfig snippet
generator for the host gcc version checks.

[--SNIP--]
> >> +# Hidden config symbols for packages to check system gcc version
> >> +config BR2_HOST_GCC_AT_LEAST_4_7
> >> +	bool
> >> +	option env="HOST_GCC_AT_LEAST_4_7"
> >> +
> >> +config BR2_HOST_GCC_AT_LEAST_4_8
> >> +	bool
> >> +	option env="HOST_GCC_AT_LEAST_4_8"
> >> +
> >> +config BR2_HOST_GCC_AT_LEAST_4_9
> >> +	bool
> >> +	option env="HOST_GCC_AT_LEAST_4_9"
> >> +
> >> +config BR2_HOST_GCC_AT_LEAST_5
> >> +	bool
> >> +	option env="HOST_GCC_AT_LEAST_5"
> > 
> > If you make each of those options actually select the N-1 option, then
> > all you need if to set one environment variable.
> 
>  Alas, that is not possible with the env option. You'd need two symbols, one for
> getting it from the environment and a real one that can be selected.

That's not what I conclude from my experiments:

    $ cat env-select.in
    comment "What is enabled?"
    config FOO
        bool
        option env="KCFG_FOO"
    config BAR
        bool
        select FOO
        option env="KCFG_BAR"
    comment "FOO=y"
        depends on FOO
    comment "BAR=y"
        depends on BAR

    $ KCFG_BAR=y mconf env-select.in
    *** What is enabled? ***
    *** FOO=y ***
    *** BAR=y ***

So, it seems BAR does indeed select FOO, no? ;-)

[--SNIP--]
> >> +* Host GCC version
> >> +** Dependency symbol: +BR2_HOST_GCC_AT_LEAST_X_Y+, (replace
> >> +   +X_Y+ with the proper version, see +Config.in+)
> >> +** Comment string: no comment to be added
> >> +** Note that it is usually not the package itself that has a minimum
> >> +   host GCC version, but rather a host-package on which it depends.
> > 
> > Well, in case the package builds an internal host tool, and properly
> > separates BUILD_CC from CC, then the restriction does apply to the
> > package itself and not a host-package.
> 
>  Yeah I know, however it's complicated to explain that well in the manual, and I
> don't believe it will ever happen in practice. Things built with BUILD_CC are
> usually pretty simple tools.

Agreed.

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'