From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andy Wingo <wingo@igalia.com>
Subject: Re: =?utf-8?Q?=E2=80=98core-updates=E2=80=99?= is back!
Date: Tue, 29 Aug 2017 11:14:07 +0200
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In-Reply-To: <878ti3uzaz.fsf@gnu.org> ("Ludovic =?utf-8?Q?Court=C3=A8s=22'?=
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To: Ludovic =?utf-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Cc: guix-devel <guix-devel@gnu.org>

On Tue 29 Aug 2017 00:01, ludo@gnu.org (Ludovic Court=C3=A8s) writes:

> Yup, I just created a new =E2=80=98core-updates=E2=80=99 branch by pushing
> <https://bugs.gnu.org/27849>.  Enjoy!
>
> Let=E2=80=99s freeze in one month, say Oct. 1st?

It would be pretty cool if we could fix our O(n^2) problems in search
paths in this core-updates -- basically whenever you go to create an
environment, instead of making e.g. VAR=3DA:B:C:..., for all VARs
(LIBRARY_PATH, PKG_CONFIG_PATH, etc), instead we make a union directory
Z containing the union of A, B, C, etc and set VAR=3DZ.  The goal would be
to fix quadratic run-time lookup costs by replacing it with a
compile-time computation.  This applies to many lookups: PATH, -rpath,
etc.

For specific variables we might also have to rewrite some internal
references, for example to replace the -L line in pkg-config files to
point to the union directory.  Dunno if there are more examples or if
PKG_CONFIG_PATH is the only one.

Andy