Re: rust work in progress conflicts (was: Re: LLVM: "FileCheck" is missing)

[Jelle Licht <jlicht@fsfe.org>]

I have taken the liberty to try my hand at finishing this, as I figured
it would be a good way for me to get more familiar with 'the Guix way'
of packaging things.

Wow, did I misjudge this rabbit hole though. It seems to be the case that
rust needs the (most recent) snapshotted binary stage-0 compiler as part
of the build process. This was not the case some years ago[1], but since
then, some 319 snapshots have been released.

Now there are two approaches which might make sense to me:

1) We package a recent stage-0 binary (thus adding yet another random
binary to the mix)

2) We bootstrap all the way from the original rust compiler, written in
ocaml. This would then presumably need to be repeated for each snapshot,
leading to about 319 iterative compiler build. On my kind-of-okay i7,
compiling a single rust iteration takes about 25 to 40 minutes.

I tentatively went with option 1, if only because I would like to see
results this decade still, and ran into several hurdles that became
quite manageable with help from the good people of #guix and
#rust-internals. One more issue yet remains: part of the rust
compilation process actually calls the 'cc linker'. This part does not
respect make flags, setenv calls or even rust's special configure flag
for setting cc.

Option 1 does not seem feasible at this point of time, but there is some
light at the end of the tunnel: rust is at some point going to follow a
convention that will allow bootstrapping compilers via 'master from
beta, beta from stable and stable from previous stable'[2].

I am currently thinking of a compromise; basically, at this moment go
for option 1, and once the policy previously described is properly
implemented by the rust team, start iteratively bootstrapping rust from
that point in time.


tldr: If we can get 'cc' in the build environment, we can have a 'dirty'
bootstrapped rust very soon. If we want to do it properly, it might take
a lot longer.  

WDYT?

[1]: https://news.ycombinator.com/item?id=8732669
[2]: https://botbot.me/mozilla/rust-internals/2016-04-29/?page=3, look
for eddyb

Nils Gillmann <niasterisk@grrlz.net> writes:

> Here is my work in progress rust.scm, it is on pause until the
> next release of rust as mentioned before:
>
>
> ~/projects/guix_project/guix/gnu/packages $ cat rust.scm
> ;;; GNU Guix --- Functional package management for GNU
> ;;; Copyright © 2016 Nils Gillmann <niasterisk@grrlz.net>
> ;;;
> ;;; This file is part of GNU Guix.
> ;;;
> ;;; GNU Guix is free software; you can redistribute it and/or modify it
> ;;; under the terms of the GNU General Public License as published by
> ;;; the Free Software Foundation; either version 3 of the License, or (at
> ;;; your option) any later version.
> ;;;
> ;;; GNU Guix is distributed in the hope that it will be useful, but
> ;;; WITHOUT ANY WARRANTY; without even the implied warranty of
> ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> ;;; GNU General Public License for more details.
> ;;;
> ;;; You should have received a copy of the GNU General Public License
> ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
>
> (define-module (gnu packages rust)
>   #:use-module ((guix licenses) #:prefix license:)
>   #:use-module (guix packages)
>   #:use-module (guix download)
>   #:use-module (guix git-download)
>   #:use-module (guix utils)
>   #:use-module (guix build-system gnu)
>   ;; #:use-module (gnu packages gcc)
>   #:use-module (gnu packages perl)
>   #:use-module (gnu packages libffi)
>   #:use-module (gnu packages valgrind)
>   #:use-module (gnu packages version-control)
>   #:use-module (gnu packages curl)
>   #:use-module (gnu packages python)
>   #:use-module (gnu packages llvm))
>
> ;;(list
> ;; (string-append
> ;; "https://github.com/rust-lang/rust/archive/"
> ;; version ".tar.gz")
> ;;gh "1m2d1dc243s7ym8fq2yag3fr5jvki0q9c39llfwgcpq1gc8jvcn8"))))
>
> (define-public rustc
>   (package
>     (name "rustc")
>     (version "1.7.0")
>     (source (origin
>               (method url-fetch)
>               (uri (string-append
>                     "https://static.rust-lang.org/dist/" name "-"
>                     version "-src.tar.gz"))
>               (file-name (string-append name "-" version ".tar.gz"))
>               (sha256
>                (base32
>                 "0fpiggrnvdmmnp6b95ik16v1h972wir9d1ydv5v8cwbvv1cn1ybd"))))
>     (build-system gnu-build-system)
>     (arguments
>      `(#:phases
>        (alist-replace
>         'configure
>         (lambda* (#:key outputs #:allow-other-keys)
>           ;; This old `configure' script doesn't support
>           ;; variables passed as arguments.
>           (let ((out (assoc-ref outputs "out"))
>                 (llvm (assoc-ref %build-inputs "llvm")))
>             (setenv "CONFIG_SHELL" (which "bash"))
>             (zero?
>              (system* "./configure"
>                       (string-append "--prefix=" out)
>                       (string-append "--llvm-root=" llvm)))))
>         %standard-phases)))
>        ;; #:configure-flags
>        ;; (list
>        ;;  (string-append "--llvm-root="
>        ;;                 (assoc-ref %build-inputs "llvm")))))
>     (inputs
>      `(("python-2" ,python-2)
>        ("curl" ,curl)
>        ("git" ,git)
>        ("valgrind" ,valgrind)
>        ("libffi" ,libffi)
>        ("perl" ,perl)
>        ("llvm" ,llvm)))
>     (home-page "https://www.rust-lang.org/")
>     (synopsis
>      "The Rust Programming Language")
>     (description
>      "LOREM IPSUM BLA")
>     (license license:gpl3+)))