From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: 'guix build --target=' handling questions
Date: Mon, 06 Mar 2017 17:04:18 +0100
Message-ID: <87y3wiqtml.fsf@gnu.org>
References: <20170221214035.6cd9f180@sf> <20170222225422.2d1020ba@sf>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Return-path: <guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:4830:134:3::10]:47280)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <ludo@gnu.org>) id 1ckv7Z-0002bN-JQ
	for guix-devel@gnu.org; Mon, 06 Mar 2017 11:04:27 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <ludo@gnu.org>) id 1ckv7U-0003Up-SC
	for guix-devel@gnu.org; Mon, 06 Mar 2017 11:04:25 -0500
In-Reply-To: <20170222225422.2d1020ba@sf> (Sergei Trofimovich's message of
	"Wed, 22 Feb 2017 22:54:22 +0000")
List-Id: "Development of GNU Guix and the GNU System distribution."
	<guix-devel.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/guix-devel/>
List-Post: <mailto:guix-devel@gnu.org>
List-Help: <mailto:guix-devel-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=subscribe>
Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org
Sender: "Guix-devel" <guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org>
To: Sergei Trofimovich <slyfox@inbox.ru>
Cc: guix-devel@gnu.org

Sergei Trofimovich <slyfox@inbox.ru> skribis:

>> Question time:
>>=20
>> - Is there a way to run 'guix environment --target=3D' in the same way a=
s 'guix build --target=3D'
>>   sets it up? I'd like to see how both compilers are supposed to be pres=
ent in there.
>>
>> - Why default g++ in PATH is the host g++ and not target g++?
>>   Target seems to make most sense if no explicit compiler is specified.
>>=20
>> - How to actually set CXX to point to target g++?
>>   It looks like implicitly there already both host (through native-input=
s)
>>   and target (through build-inputs) compilers available.
>>   I would expect something like
>>       #:make-flags (list (string-append "CXX=3D" <.?.>))=20
>>   What should be in place of that "<.?.>" to refer to target g++?
>
> I think I've found a workaround at least for my third question.
>
> Both host and target compilers are available as g++ and ${target}-g++.
>
> Thus the following workaround seems to work:
>
> diff --git a/gnu/packages/regex.scm b/gnu/packages/regex.scm
> index f04cba706..a8fa689ab 100644
> --- a/gnu/packages/regex.scm
> +++ b/gnu/packages/regex.scm
> @@ -20,11 +20,13 @@
>
>  (define-module (gnu packages regex)
>    #:use-module ((guix licenses) #:prefix license:)
>    #:use-module (guix packages)
>    #:use-module (guix download)
> -  #:use-module (guix build-system gnu))
> +  #:use-module (guix build-system gnu)
> +  #:use-module (guix utils) ; for %current-target-system
> +  )
>
>  (define-public re2
>     (package
>       (name "re2")
>       (version "2017-01-01")
> @@ -40,11 +42,15 @@
>                   "0yij1ajh66h3pj3kfz7y0ldrsww8rlpjzaavyr5lchl98as1jq74")=
)))
>       (build-system gnu-build-system)
>       (arguments
>        `(#:test-target "test"
>          ;; There is no configure step, but the Makefile respects a prefi=
x.
> -        #:make-flags (list (string-append "prefix=3D" %output))
> +        #:make-flags (list (string-append "prefix=3D" %output)
> +                           (string-append "CXX=3D" ,(string-append (if (=
%current-target-system)
> +                                                                     (st=
ring-append (%current-target-system) "-")
> +                                                                     "")
> +                                                                 "g++")))

As John wrote, this is the right fix for this package.

If you can send it with =E2=80=98git send-email=E2=80=99 (see
<https://www.gnu.org/software/guix/manual/html_node/Submitting-Patches.html=
>),
I=E2=80=99ll apply it right away.  Otherwise I can do it on your behalf.

Thanks!

Ludo=E2=80=99.