From mboxrd@z Thu Jan 1 00:00:00 1970 From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=) Subject: Re: Why is die "doc" output downloaded when building this package? Date: Sat, 05 Nov 2016 22:53:57 +0100 Message-ID: <871syp61ai.fsf@gnu.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: (Hartmut Goebel's message of "Sat, 5 Nov 2016 18:03:28 +0100") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-guix-bounces+gcggh-help-guix=m.gmane.org@gnu.org Sender: "Help-Guix" To: Hartmut Goebel Cc: bug-guix@gnu.org, help-guix@gnu.org List-Id: bug-guix.gnu.org Hi, (Adding a bug at bug-guix@gnu.org.) Hartmut Goebel skribis: > when building this package, qt-4.8.7-doc (the doc-output of qt-4.7.8) > will be downloaded. I do not understand why. Most likely this is due to a limitation of the current implementation of grafts: all the outputs of packages on a =E2=80=9Cgrafting path=E2=80=9D ne= ed to be downloaded, even if some of these outputs are unused. This is because =E2=80=98graft-derivation=E2=80=99 takes a derivation, such= as Qt=E2=80=99s, and returns a derivation with as many outputs, but marked as non-substitutable (locally built). Because it=E2=80=99s locally built, all= the outputs of the original derivation must be fetched just to be able to build the grafted derivation, even if only one of those outputs is needed. I think we could fix that by creating one graft derivation for each output of the original derivation. Thanks, Ludo=E2=80=99.