-*- mode: org; coding: utf-8; -*-

Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>

  Copying and distribution of this file, with or without modification,
  are permitted in any medium without royalty provided the copyright
  notice and this notice are preserved.

* integrate needed Nix code

Guix uses Nix’s daemon (‘nix-worker’, later renamed to ‘nix-daemon’) to
actually perform builds, scheduling, substitution of pre-built binaries,
and GC-related tasks.  The daemon mainly uses ‘libstore’ from Nix.
Integrating it in Guix itself will make Guix self-contained, thereby
simplifying our users’ lives.

** Remove dependency on OpenSSL

The ‘openssl’ command-line tool is used in libstore to sign store paths
to be exported, and to check such signatures.  The signing keys are
usually in /etc/nix/signing-key.{pub,sec}.  They are a PKCS#8-encoded
X.509 SubjectPublicKeyInfo.  These can be decoded with the [[http://lists.gnu.org/archive/html/help-gnutls/2012-12/msg00012.html][C API of
GnuTLS]], but not yet with its Guile bindings.  There’s also
‘gnutls_privkey_sign_data’ to sign, and related functions.

** Add a binary cache substituter

Like scripts/download-from-binary-cache.pl in Nix, but written in
Scheme.  Substituters allow pre-built binaries to be downloaded when
they are available from a trusted source.

** Add a remote build hook

Like scripts/build-remote.pl in Nix.

* infrastructure

** have a Hydra instance build Guix packages

[[http://nixos.org/hydra/][Hydra]] is a continuous integration tool based on Nix.  It now has
[[https://github.com/NixOS/hydra/commit/f27ae1d5663680400cb99cfb898970f34d8d21be][Guile/Guix support]], which allows “build recipes” written in Guile using
Guix to be used directly on Hydra.

For a start, we may use the instance at hydra.nixos.org, generously
provided by TU Delft.  However, in the future, we may want to setup our
own instance at gnu.org.

* extend <origin>
** add OpenPGP signatures:

   (origin
     (method http-fetch)
     (uri "http://.../foo.tgz")
     (signature-uri (string-append uri ".sig"))
     (signer-openpgp-fingerprint "..."))

** allow <origin> to be a derivation/package or a file

* extend <package>

** add support for ‘search-paths’

This should be passed to the build system, to extend package-specific
search path environment variables–like ‘GUILE_LOAD_PATH’, ‘PERL5LIB’,
etc.

** add a ‘user-environment-hook’

This should specify builder code to be run when building a user
environment with ‘guix-package’.  For instance, Texinfo’s hook would
create a new ‘dir’.

** add ‘patches’ there

** extend ‘propagated-build-inputs’ with support for multiple outputs

#+BEGIN_SRC scheme
  (outputs '("out" "include"))
  (propagated-build-inputs
    `(((("i1" ,p1 "o1")
        ("i2" ,p2))
       => "include")
      ("i3" ,p3)))
#+END_SRC

* support cross-compilation

Implement ‘package-cross-derivation’, and add the corresponding code in
‘gnu-build-system’.  Then, actually bootstrap a cross-compilation
environment–e.g., a cross-GNU environment.

* gnu-build-system: produce a ‘debug’ derivation

Set a .gnu_debuglink in the main derivations to point to the sibling
file name (only the basename, to not retain a dependency on the ‘debug’
derivation.)

For /nix/store/xyz-foobar/bin/foo, we should have
/nix/store/abc-foobar-debug/lib/nix/store/xyz-foobar/bin/foo.debug (info
"(gdb) Separate Debug Files").

Users should have a default GDB setting with ~/.guix-profile/lib/debug
as their ‘debug-file-directory’.

* build-expression->derivation: define `%system' in the builder

Would allow build expressions to have system-dependent code, like
`glibc-dynamic-linker'.

* add ‘allowed-references’ in <package>

[[file:~/src/nix/src/libstore/build.cc::if%20(drv.env.find("allowedReferences")%20!%3D%20drv.env.end())%20{][See how Nix implements that internally]].

* union

Support sophisticated collision handling when building a union: check
whether the colliding files are identical, honor per-package priorities,
etc.

* guix-package

** add ‘--roll-back’
** add ‘--list-generations’, and ‘--delete-generations’
** add ‘--upgrade’
** add ‘--search’

* guix build utils
** Add equivalent to "rm -rf"
** Add equivalent to Nixpkgs's ‘wrapProgram’
** Add equivalent to chrpath, possibly using [[https://gitorious.org/guile-dlhacks/guile-dlhacks/][guile-dlhacks]]

* distro
** choose a name! (Jinn?)
** port to new GNU/Linux platforms, notably ‘mipsel64-linux’
** port to GNU/Hurd, aka. ‘i686-gnu’

Problems include that current glibc releases do not build on GNU/Hurd.
In addition, there haven’t been stable releases of GNU Mach, MiG, and
Hurd, which would be a pre-condition.

** make a bootable GNU/Linux-Libre distro, with OS configuration EDSL

Similar in spirit to /etc/nixos/configuration.nix.