bug#27271: [PATCH 0/4] Catch collisions at profile creation time

[Ludovic Courtès]

Hello Guix!

These patches allow us to catch problematic collisions when computing
a profile derivation.  As we know, the profile builder often spits out
a number of warnings about collisions but that is not very useful because
users cannot distinguish the problematic cases from the harmless cases
(an example of a harmless case is when GDB and Binutils provide an
almost-identical .info file twice).

Concretely, what happens is something like this:

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix package -i guile-cairo -n
The following package would be upgraded:
   guile-cairo  1.4.1 → 1.4.1   
/gnu/store/k9p7j9ijb9vfkmvcgr4vqy20vkg6nsbg-guile-cairo-1.4.1

guix package: error: profile contains conflicting entries for guile-cairo:out
guix package: error:   first entry: address@hidden:out 
/gnu/store/k9p7j9ijb9vfkmvcgr4vqy20vkg6nsbg-guile-cairo-1.4.1
guix package: error:   second entry: address@hidden:out 
/gnu/store/x0jp2q06snx7skrqdmlkn0r5fhyvvn00-guile-cairo-1.4.1
guix package: error:    ... propagated from address@hidden
$ ./pre-inst-env guix package -i guile-cairo guile-rsvg guile-present -n
The following packages would be upgraded:
   guile-cairo  1.4.1 → 1.4.1   
/gnu/store/k9p7j9ijb9vfkmvcgr4vqy20vkg6nsbg-guile-cairo-1.4.1
   guile-rsvg   2.18.1 → 2.18.1 
/gnu/store/xp8wcyvhplsv45gkj9r4n6zmcdancfkn-guile-rsvg-2.18.1
   guile-present        0.3.0 → 0.3.0   
/gnu/store/qwk8fzijyllaxv4vw114gqzix1qvfmp2-guile-present-0.3.0

guix package: error: profile contains conflicting entries for guile-cairo:out
guix package: error:   first entry: address@hidden:out 
/gnu/store/k9p7j9ijb9vfkmvcgr4vqy20vkg6nsbg-guile-cairo-1.4.1
guix package: error:   second entry: address@hidden:out 
/gnu/store/x0jp2q06snx7skrqdmlkn0r5fhyvvn00-guile-cairo-1.4.1
guix package: error:    ... propagated from address@hidden
$ ./pre-inst-env guix package -i guile-cairo guile-rsvg guile-charting 
guile-present -n
The following packages would be upgraded:
   guile-cairo  1.4.1 → 1.4.1   
/gnu/store/k9p7j9ijb9vfkmvcgr4vqy20vkg6nsbg-guile-cairo-1.4.1
   guile-rsvg   2.18.1 → 2.18.1 
/gnu/store/xp8wcyvhplsv45gkj9r4n6zmcdancfkn-guile-rsvg-2.18.1
   guile-charting       0.2.0 → 0.2.0   
/gnu/store/11368xymyhk4zz8zwvbdmp5dzcl0vxvc-guile-charting-0.2.0
   guile-present        0.3.0 → 0.3.0   
/gnu/store/qwk8fzijyllaxv4vw114gqzix1qvfmp2-guile-present-0.3.0

substitute: updating list of substitutes from 'https://bayfront.guixsd.org'... 
100.0%
substitute: updating list of substitutes from 'https://mirror.hydra.gnu.org'... 
100.0%
The following derivations would be built:
   /gnu/store/r361w7fa57vm7js8lk4bnsc7lwv2avby-profile.drv
   /gnu/store/l5hf8cg5fx6par39659ihkhdgp3kls1n-xdg-mime-database.drv
   /gnu/store/k8jmvc8yjk3qg8xbgcfgpgngq7vkygld-info-dir.drv
   /gnu/store/ivnqmwwxwric5lhw5gqnpkxq6gbzj23i-fonts-dir.drv
   /gnu/store/hdaasxvm64h06xxzwrnx2gch981h88wf-ca-certificate-bundle.drv
   /gnu/store/axzp9vj4h59nnbmf6ccaajb9qq97xwb8-gtk-icon-themes.drv
   /gnu/store/8dkb7k53x1c0zhb9qdgrgr53j5j3biwf-gtk-im-modules.drv
   /gnu/store/v2w6qpf0kk2d70wv01f3ln1v758sgzqm-manual-database.drv
--8<---------------cut here---------------end--------------->8---

As in the example above, conflicts may arise when doing a partial
upgrade of a profile, because this is a situation where you can easily
end up with conflicting versions of a given package.  It’s much less
likely when using ‘guix package -m’ or similar.

An open question is whether there are commonly used combinations of
packages that trigger conflicts.  I haven’t had any problems with my
profile (with 234 packages) nor with my GuixSD config, but I encourage
you to test it on your profile!

Thoughts?

Ludo’.

Ludovic Courtès (3):
  profiles: Represent propagated inputs as manifest entries.
  profiles: Manifest entries keep a reference to their parent entry.
  profiles: Catch and report collisions in the profile.

 guix/profiles.scm  | 241 +++++++++++++++++++++++++++++++++++++++++------------
 guix/ui.scm        |  27 ++++++
 tests/profiles.scm |  87 +++++++++++++++++++
 3 files changed, 301 insertions(+), 54 deletions(-)

-- 
2.13.0