Merge branch 'master' into core-updates

9 files changed, 382 insertions, 292 deletions

diff --git a/build-aux/build-self.scm b/build-aux/build-self.scm
index 4c85c09df6..bccb7a959e 100644
--- a/build-aux/build-self.scm
+++ b/build-aux/build-self.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2014, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -19,10 +19,14 @@
 (define-module (build-self)
   #:use-module (gnu)
   #:use-module (guix)
+  #:use-module (guix ui)
   #:use-module (guix config)
+  #:use-module (guix modules)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-19)
+  #:use-module (rnrs io ports)
   #:use-module (ice-9 match)
+  #:use-module (ice-9 popen)
   #:export (build))
 
 ;;; Commentary:
@@ -40,242 +44,256 @@
 ;;; Code:
 
 
-;; The dependencies.  Don't refer explicitly to the variables because they
-;; could be renamed or shuffled around in modules over time.  Conversely,
-;; 'find-best-packages-by-name' is expected to always have the same semantics.
-
-(define guix
-  (first (find-best-packages-by-name "guix" #f)))
-
-(define libgcrypt
-  (first (find-best-packages-by-name "libgcrypt" #f)))
-
-(define zlib
-  (first (find-best-packages-by-name "zlib" #f)))
-
-(define gzip
-  (first (find-best-packages-by-name "gzip" #f)))
-
-(define bzip2
-  (first (find-best-packages-by-name "bzip2" #f)))
-
-(define xz
-  (first (find-best-packages-by-name "xz" #f)))
-
-(define (false-if-wrong-guile package)
-  "Return #f if PACKAGE depends on the \"wrong\" major version of Guile (e.g.,
-2.0 instead of 2.2), otherwise return PACKAGE."
-  (let ((guile (any (match-lambda
-                      ((label (? package? dep) _ ...)
-                       (and (string=? (package-name dep) "guile")
-                            dep)))
-                    (package-direct-inputs package))))
-    (and (or (not guile)
-             (string-prefix? (effective-version)
-                             (package-version guile)))
-         package)))
-
-(define (package-for-current-guile . names)
-  "Return the package with one of the given NAMES that depends on the current
-Guile major version (2.0 or 2.2), or #f if none of the packages matches."
-  (let loop ((names names))
-    (match names
-      (()
-       #f)
-      ((name rest ...)
-       (match (find-best-packages-by-name name #f)
-         (()
-          (loop rest))
-         ((first _ ...)
-          (or (false-if-wrong-guile first)
-              (loop rest))))))))
-
-(define guile-json
-  (package-for-current-guile "guile-json"
-                             "guile2.2-json"
-                             "guile2.0-json"))
-
-(define guile-ssh
-  (package-for-current-guile "guile-ssh"
-                             "guile2.2-ssh"
-                             "guile2.0-ssh"))
-
-(define guile-git
-  (package-for-current-guile "guile-git"
-                             "guile2.0-git"))
-
-(define guile-bytestructures
-  (package-for-current-guile "guile-bytestructures"
-                             "guile2.0-bytestructures"))
-
-;; The actual build procedure.
+;;;
+;;; Generating (guix config).
+;;;
+;;; This is copied from (guix self) because we cannot assume (guix self) is
+;;; available at this point.
+;;;
+
+(define %dependency-variables
+  ;; (guix config) variables corresponding to dependencies.
+  '(%libgcrypt %libz %xz %gzip %bzip2 %nix-instantiate))
+
+(define %persona-variables
+  ;; (guix config) variables that define Guix's persona.
+  '(%guix-package-name
+    %guix-version
+    %guix-bug-report-address
+    %guix-home-page-url))
+
+(define %config-variables
+  ;; (guix config) variables corresponding to Guix configuration (storedir,
+  ;; localstatedir, etc.)
+  (sort (filter pair?
+                (module-map (lambda (name var)
+                              (and (not (memq name %dependency-variables))
+                                   (not (memq name %persona-variables))
+                                   (cons name (variable-ref var))))
+                            (resolve-interface '(guix config))))
+        (lambda (name+value1 name+value2)
+          (string<? (symbol->string (car name+value1))
+                    (symbol->string (car name+value2))))))
+
+(define* (make-config.scm #:key libgcrypt zlib gzip xz bzip2
+                          (package-name "GNU Guix")
+                          (package-version "0")
+                          (bug-report-address "bug-guix@gnu.org")
+                          (home-page-url "https://gnu.org/s/guix"))
+
+  ;; Hack so that Geiser is not confused.
+  (define defmod 'define-module)
+
+  (scheme-file "config.scm"
+               #~(begin
+                   (#$defmod (guix config)
+                     #:export (%guix-package-name
+                               %guix-version
+                               %guix-bug-report-address
+                               %guix-home-page-url
+                               %libgcrypt
+                               %libz
+                               %gzip
+                               %bzip2
+                               %xz
+                               %nix-instantiate))
+
+                   ;; XXX: Work around <http://bugs.gnu.org/15602>.
+                   (eval-when (expand load eval)
+                     #$@(map (match-lambda
+                               ((name . value)
+                                #~(define-public #$name #$value)))
+                             %config-variables)
+
+                     (define %guix-package-name #$package-name)
+                     (define %guix-version #$package-version)
+                     (define %guix-bug-report-address #$bug-report-address)
+                     (define %guix-home-page-url #$home-page-url)
+
+                     (define %gzip
+                       #+(and gzip (file-append gzip "/bin/gzip")))
+                     (define %bzip2
+                       #+(and bzip2 (file-append bzip2 "/bin/bzip2")))
+                     (define %xz
+                       #+(and xz (file-append xz "/bin/xz")))
+
+                     (define %libgcrypt
+                       #+(and libgcrypt
+                              (file-append libgcrypt "/lib/libgcrypt")))
+                     (define %libz
+                       #+(and zlib
+                              (file-append zlib "/lib/libz")))
+
+                     (define %nix-instantiate     ;for (guix import snix)
+                       "nix-instantiate")))))
 
-(define (top-source-directory)
-  "Return the name of the top-level directory of this source tree."
-  (and=> (assoc-ref (current-source-location) 'filename)
-         (lambda (file)
-           (string-append (dirname file) "/.."))))
+
+;;;
+;;; 'gexp->script'.
+;;;
+;;; This is our own variant of 'gexp->script' with an extra #:module-path
+;;; parameter, which was unavailable in (guix gexp) until commit
+;;; 1ae16033f34cebe802023922436883867010850f (March 2018.)
+;;;
 
+(define (load-path-expression modules path)
+  "Return as a monadic value a gexp that sets '%load-path' and
+'%load-compiled-path' to point to MODULES, a list of module names.  MODULES
+are searched for in PATH."
+  (mlet %store-monad ((modules  (imported-modules modules
+                                                  #:module-path path))
+                      (compiled (compiled-modules modules
+                                                  #:module-path path)))
+    (return (gexp (eval-when (expand load eval)
+                    (set! %load-path
+                      (cons (ungexp modules) %load-path))
+                    (set! %load-compiled-path
+                      (cons (ungexp compiled)
+                            %load-compiled-path)))))))
+
+(define* (gexp->script name exp
+                       #:key (guile (default-guile))
+                       (module-path %load-path))
+  "Return an executable script NAME that runs EXP using GUILE, with EXP's
+imported modules in its search path."
+  (mlet %store-monad ((set-load-path
+                       (load-path-expression (gexp-modules exp)
+                                             module-path)))
+    (gexp->derivation name
+                      (gexp
+                       (call-with-output-file (ungexp output)
+                         (lambda (port)
+                           ;; Note: that makes a long shebang.  When the store
+                           ;; is /gnu/store, that fits within the 128-byte
+                           ;; limit imposed by Linux, but that may go beyond
+                           ;; when running tests.
+                           (format port
+                                   "#!~a/bin/guile --no-auto-compile~%!#~%"
+                                   (ungexp guile))
+
+                           (write '(ungexp set-load-path) port)
+                           (write '(ungexp exp) port)
+                           (chmod port #o555))))
+                      #:module-path module-path)))
 
+
 (define (date-version-string)
   "Return the current date and hour in UTC timezone, for use as a poor
 person's version identifier."
   ;; XXX: Replace with a Git commit id.
   (date->string (current-date 0) "~Y~m~d.~H"))
 
-(define (matching-guile-2.2)
-  "Return a Guile 2.2 with the same version as the current one or immediately
-older than then current one.  This is so that we do not build ABI-incompatible
-objects.  See <https://bugs.gnu.org/29570>."
-  (let loop ((packages (find-packages-by-name "guile" "2.2"))
-             (best     #f))
-    (match packages
-      (()
-       best)
-      ((head tail ...)
-       (if (string=? (package-version head) (version))
-           head
-           (if best
-               (if (version>? (package-version head) (version))
-                   (loop tail best)
-                   (loop tail head))
-               (loop tail head)))))))
-
-(define (guile-for-build)
-  "Return a derivation for Guile 2.0 or 2.2, whichever matches the currently
-running Guile."
-  (package->derivation (cond-expand
-                         (guile-2.2
-                          (canonical-package (matching-guile-2.2)))
-                         (else
-                          (canonical-package
-                           (specification->package "guile@2.0"))))))
+(define* (build-program source version
+                        #:optional (guile-version (effective-version)))
+  "Return a program that computes the derivation to build Guix from SOURCE."
+  (define select?
+    ;; Select every module but (guix config) and non-Guix modules.
+    (match-lambda
+      (('guix 'config) #f)
+      (('guix _ ...)   #t)
+      (('gnu _ ...)    #t)
+      (_               #f)))
+
+  (with-imported-modules `(((guix config)
+                            => ,(make-config.scm
+                                 #:libgcrypt
+                                 (specification->package "libgcrypt")))
+                           ,@(source-module-closure `((guix store)
+                                                      (guix self)
+                                                      (guix derivations)
+                                                      (gnu packages bootstrap))
+                                                    (list source)
+                                                    #:select? select?))
+    (gexp->script "compute-guix-derivation"
+                  #~(begin
+                      (use-modules (ice-9 match))
+
+                      (eval-when (expand load eval)
+                        ;; Don't augment '%load-path'.
+                        (unsetenv "GUIX_PACKAGE_PATH")
+
+                        ;; (gnu packages …) modules are going to be looked up
+                        ;; under SOURCE.  (guix config) is looked up in FRONT.
+                        (match %load-path
+                          ((#$source _ ...)
+                           #t)                    ;already done
+                          ((front _ ...)
+                           (set! %load-path (list #$source front))))
+
+                        ;; Only load our own modules or those of Guile.
+                        (match %load-compiled-path
+                          ((front _ ... sys1 sys2)
+                           (set! %load-compiled-path
+                             (list front sys1 sys2)))))
+
+                      (use-modules (guix store)
+                                   (guix self)
+                                   (guix derivations)
+                                   (srfi srfi-1))
+
+                      (define (spin system)
+                        (define spin
+                          (circular-list "-" "\\" "|" "/" "-" "\\" "|" "/"))
+
+                        (format (current-error-port)
+                                "Computing Guix derivation for '~a'...  "
+                                system)
+                        (let loop ((spin spin))
+                          (display (string-append "\b" (car spin))
+                                   (current-error-port))
+                          (force-output (current-error-port))
+                          (sleep 1)
+                          (loop (cdr spin))))
+
+                      (match (command-line)
+                        ((_ _ system)
+                         (with-store store
+                           (call-with-new-thread
+                            (lambda ()
+                              (spin system)))
+
+                           (display
+                            (derivation-file-name
+                             (run-with-store store
+                               (guix-derivation #$source #$version
+                                                #$guile-version)
+                               #:system system)))))))
+                  #:module-path (list source))))
 
 ;; The procedure below is our return value.
 (define* (build source
-                #:key verbose? (version (date-version-string))
+                #:key verbose? (version (date-version-string)) system
+                (guile-version (match ((@ (guile) version))
+                                 ("2.2.2" "2.2.2")
+                                 (_       (effective-version))))
                 #:allow-other-keys
                 #:rest rest)
   "Return a derivation that unpacks SOURCE into STORE and compiles Scheme
 files."
-  ;; The '%xxxdir' variables were added to (guix config) in July 2016 so we
-  ;; cannot assume that they are defined.  Try to guess their value when
-  ;; they're undefined (XXX: we get an incorrect guess when environment
-  ;; variables such as 'NIX_STATE_DIR' are defined!).
-  (define storedir
-    (if (defined? '%storedir) %storedir %store-directory))
-  (define localstatedir
-    (if (defined? '%localstatedir) %localstatedir (dirname %state-directory)))
-  (define sysconfdir
-    (if (defined? '%sysconfdir) %sysconfdir (dirname %config-directory)))
-
-  (define builder
-    #~(begin
-        (use-modules (guix build pull))
-
-        (letrec-syntax ((maybe-load-path
-                         (syntax-rules ()
-                           ((_ item rest ...)
-                            (let ((tail (maybe-load-path rest ...)))
-                              (if (string? item)
-                                  (cons (string-append item
-                                                       "/share/guile/site/"
-                                                       #$(effective-version))
-                                        tail)
-                                  tail)))
-                           ((_)
-                            '()))))
-          (set! %load-path
-                (append
-                 (maybe-load-path #$guile-json #$guile-ssh
-                                  #$guile-git #$guile-bytestructures)
-                 %load-path)))
-
-        (letrec-syntax ((maybe-load-compiled-path
-                         (syntax-rules ()
-                           ((_ item rest ...)
-                            (let ((tail (maybe-load-compiled-path rest ...)))
-                              (if (string? item)
-                                  (cons (string-append item
-                                                       "/lib/guile/"
-                                                       #$(effective-version)
-                                                       "/site-ccache")
-                                        tail)
-                                  tail)))
-                           ((_)
-                            '()))))
-          (set! %load-compiled-path
-                (append
-                 (maybe-load-compiled-path #$guile-json #$guile-ssh
-                                           #$guile-git #$guile-bytestructures)
-                 %load-compiled-path)))
-
-        ;; XXX: The 'guile-ssh' package prior to Guix commit 92b7258 was
-        ;; broken: libguile-ssh could not be found.  Work around that.
-        ;; FIXME: We want Guile-SSH 0.10.2 or later anyway.
-        #$(if (string-prefix? "0.9." (package-version guile-ssh))
-              #~(setenv "LTDL_LIBRARY_PATH" (string-append #$guile-ssh "/lib"))
-              #t)
-
-        (build-guix #$output #$source
-
-                    #:system #$%system
-                    #:storedir #$storedir
-                    #:localstatedir #$localstatedir
-                    #:sysconfdir #$sysconfdir
-                    #:sbindir (string-append #$guix "/sbin")
-
-                    #:package-name #$%guix-package-name
-                    #:package-version #$version
-                    #:bug-report-address #$%guix-bug-report-address
-                    #:home-page-url #$%guix-home-page-url
-
-                    #:libgcrypt #$libgcrypt
-                    #:zlib #$zlib
-                    #:gzip #$gzip
-                    #:bzip2 #$bzip2
-                    #:xz #$xz
-
-                    ;; XXX: This is not perfect, enabling VERBOSE? means
-                    ;; building a different derivation.
-                    #:debug-port (if #$verbose?
-                                     (current-error-port)
-                                     (%make-void-port "w")))))
-
-  (unless guile-git
-    ;; XXX: Guix before February 2017 lacks a 'guile-git' package altogether.
-    ;; If we try to upgrade anyway, the logic in (guix scripts pull) will not
-    ;; build (guix git), which will leave us with an unusable 'guix pull'.  To
-    ;; avoid that, fail early.
-    (format (current-error-port)
-            "\
-Your installation is too old and lacks a '~a' package.
-Please upgrade to an intermediate version first, for instance with:
-
-  guix pull --url=https://git.savannah.gnu.org/cgit/guix.git/snapshot/v0.13.0.tar.gz
-\n"
-            (match (effective-version)
-              ("2.0" "guile2.0-git")
-              (_     "guile-git")))
-    (exit 1))
-
-  (mlet %store-monad ((guile (guile-for-build)))
-    (gexp->derivation "guix-latest" builder
-                      #:modules '((guix build pull)
-                                  (guix build utils)
-                                  (guix build compile)
-
-                                  ;; Closure of (guix modules).
-                                  (guix modules)
-                                  (guix memoization)
-                                  (guix profiling)
-                                  (guix sets))
-
-                      ;; Arrange so that our own (guix build …) modules are
-                      ;; used.
-                      #:module-path (list (top-source-directory))
-
-                      #:guile-for-build guile)))
+  ;; Build the build program and then use it as a trampoline to build from
+  ;; SOURCE.
+  (mlet %store-monad ((build  (build-program source version guile-version))
+                      (system (if system (return system) (current-system))))
+    (mbegin %store-monad
+      (show-what-to-build* (list build))
+      (built-derivations (list build))
+      (let* ((pipe   (begin
+                       (setenv "GUILE_WARN_DEPRECATED" "no") ;be quiet and drive
+                       (open-pipe* OPEN_READ
+                                   (derivation->output-path build)
+                                   source system)))
+             (str    (get-string-all pipe))
+             (status (close-pipe pipe)))
+        (match str
+          ((? eof-object?)
+           (error "build program failed" (list build status)))
+          ((? derivation-path? drv)
+           (mbegin %store-monad
+             (return (newline (current-output-port)))
+             ((store-lift add-temp-root) drv)
+             (return (read-derivation-from-file drv))))
+          ((? string? str)
+           (error "invalid build result" (list build str))))))))
 
 ;; This file is loaded by 'guix pull'; return it the build procedure.
 build
diff --git a/build-aux/compile-as-derivation.scm b/build-aux/compile-as-derivation.scm
new file mode 100644
index 0000000000..afb134a92a
--- /dev/null
+++ b/build-aux/compile-as-derivation.scm
@@ -0,0 +1,53 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; 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/>.
+
+;; Build Guix using Guix.
+
+(use-modules (srfi srfi-26))
+
+;; Add ~/.config/guix/latest to the search path.
+(add-to-load-path
+ (and=> (or (getenv "XDG_CONFIG_HOME")
+            (and=> (getenv "HOME")
+                   (cut string-append <> "/.config")))
+        (cut string-append <> "/guix/latest")))
+
+(use-modules (guix) (guix ui)
+             (guix git-download)
+             (ice-9 match))
+
+(match (command-line)
+  ((program source)
+   (with-error-handling
+     (with-store store
+       (let* ((script (string-append source "/build-aux/build-self.scm"))
+              (build  (primitive-load script))
+              (git?   (git-predicate source)))
+         (run-with-store store
+           ;; TODO: Extract #:version and #:commit using Guile-Git.
+           (mlet* %store-monad ((source (interned-file source "guix-source"
+                                                       #:select? git?
+                                                       #:recursive? #t))
+                                (drv    (build source)))
+             (mbegin %store-monad
+               (show-what-to-build* (list drv))
+               (built-derivations (list drv))
+               (with-monad %store-monad
+                 (display (derivation->output-path drv))
+                 (newline)
+                 (return drv))))))))))
diff --git a/build-aux/cuirass/gnu-system.scm b/build-aux/cuirass/gnu-system.scm
index f545ba03bc..0eb834cfba 100644
--- a/build-aux/cuirass/gnu-system.scm
+++ b/build-aux/cuirass/gnu-system.scm
@@ -21,29 +21,5 @@
 ;;; tool.
 ;;;
 
-(include-from-path "build-aux/hydra/gnu-system.scm")
-
-(use-modules ((guix licenses)
-              #:select (license? license-name license-uri license-comment)))
-
-(define (cuirass-jobs store arguments)
-  "Return Cuirass jobs."
-  (map hydra-job->cuirass-job (hydra-jobs store arguments)))
-
-(define (hydra-job->cuirass-job hydra-job)
-  (let ((name (car hydra-job))
-        (job ((cdr hydra-job))))
-    (lambda _ (acons #:job-name (symbol->string name)
-                     (map symbol-alist-entry->keyword-alist-entry job)))))
-
-(define (symbol-alist-entry->keyword-alist-entry entry)
-  (cons (symbol->keyword (car entry)) (entry->sexp-entry (cdr entry))))
-
-(define (entry->sexp-entry o)
-  (match o
-    ((? license?) `((name . (license-name o))
-                    (uri . ,(license-uri o))
-                    (comment . ,(license-comment o))))
-    ((lst ...)
-     (map entry->sexp-entry lst))
-    (_ o)))
+(include "../hydra/gnu-system.scm")
+(include "hydra-to-cuirass.scm")
diff --git a/build-aux/cuirass/guix-modular.scm b/build-aux/cuirass/guix-modular.scm
new file mode 100644
index 0000000000..cbbdbf1133
--- /dev/null
+++ b/build-aux/cuirass/guix-modular.scm
@@ -0,0 +1,6 @@
+;;;
+;;; This file defines Cuirass build jobs to build Guix itself.
+;;;
+
+(include "../hydra/guix-modular.scm")
+(include "hydra-to-cuirass.scm")
diff --git a/build-aux/cuirass/hydra-to-cuirass.scm b/build-aux/cuirass/hydra-to-cuirass.scm
new file mode 100644
index 0000000000..75c77ea35a
--- /dev/null
+++ b/build-aux/cuirass/hydra-to-cuirass.scm
@@ -0,0 +1,47 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
+;;;
+;;; 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/>.
+
+;;;
+;;; This file defines the conversion of Hydra build jobs to Cuirass build
+;;; jobs.  It is meant to be included in other files.
+;;;
+
+(use-modules ((guix licenses)
+              #:select (license? license-name license-uri license-comment)))
+
+(define (cuirass-jobs store arguments)
+  "Return Cuirass jobs."
+  (map hydra-job->cuirass-job (hydra-jobs store arguments)))
+
+(define (hydra-job->cuirass-job hydra-job)
+  (let ((name (car hydra-job))
+        (job ((cdr hydra-job))))
+    (lambda _ (acons #:job-name (symbol->string name)
+                     (map symbol-alist-entry->keyword-alist-entry job)))))
+
+(define (symbol-alist-entry->keyword-alist-entry entry)
+  (cons (symbol->keyword (car entry)) (entry->sexp-entry (cdr entry))))
+
+(define (entry->sexp-entry o)
+  (match o
+    ((? license?) `((name . (license-name o))
+                    (uri . ,(license-uri o))
+                    (comment . ,(license-comment o))))
+    ((lst ...)
+     (map entry->sexp-entry lst))
+    (_ o)))
diff --git a/build-aux/hydra/evaluate.scm b/build-aux/hydra/evaluate.scm
index 8e391f44fd..5793c022ff 100644
--- a/build-aux/hydra/evaluate.scm
+++ b/build-aux/hydra/evaluate.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -79,7 +79,8 @@ Otherwise return THING."
 (match (command-line)
   ((command file cuirass? ...)
    ;; Load FILE, a Scheme file that defines Hydra jobs.
-   (let ((port (current-output-port)))
+   (let ((port (current-output-port))
+         (real-build-things build-things))
      (save-module-excursion
       (lambda ()
         (set-current-module %user-module)
@@ -93,13 +94,15 @@ Otherwise return THING."
 
        ;; Grafts can trigger early builds.  We do not want that to happen
        ;; during evaluation, so use a sledgehammer to catch such problems.
+       ;; An exception, though, is the evaluation of Guix itself, which
+       ;; requires building a "trampoline" program.
        (set! build-things
          (lambda (store . args)
            (format (current-error-port)
-                   "error: trying to build things during evaluation!~%")
+                   "warning: building things during evaluation~%")
            (format (current-error-port)
                    "'build-things' arguments: ~s~%" args)
-           (exit 1)))
+           (apply real-build-things store args)))
 
        ;; Call the entry point of FILE and print the resulting job sexp.
        (pretty-print
diff --git a/build-aux/hydra/gnu-system.scm b/build-aux/hydra/gnu-system.scm
index 8178871747..62eb957f83 100644
--- a/build-aux/hydra/gnu-system.scm
+++ b/build-aux/hydra/gnu-system.scm
@@ -24,7 +24,7 @@
 
 (use-modules (system base compile))
 
-(eval-when (compile load eval)
+(eval-when (expand load eval)
 
   ;; Pre-load the compiler so we don't end up auto-compiling it.
   (compile #t)
@@ -32,6 +32,15 @@
   ;; Use our very own Guix modules.
   (set! %fresh-auto-compile #t)
 
+  ;; Ignore .go files except for Guile's.  This is because our checkout in the
+  ;; store has mtime set to the epoch, and thus .go files look newer, even
+  ;; though they may not correspond.  Use 'reverse' so that /gnu/store/…-guile
+  ;; comes before /run/current-system/profile.
+  (set! %load-compiled-path
+    (list
+     (dirname (dirname (search-path (reverse %load-compiled-path)
+                                    "ice-9/boot-9.go")))))
+
   (and=> (assoc-ref (current-source-location) 'filename)
          (lambda (file)
            (let ((dir (string-append (dirname file) "/../..")))
diff --git a/build-aux/hydra/guix-modular.scm b/build-aux/hydra/guix-modular.scm
index bdbb2fa8d5..58e09e1831 100644
--- a/build-aux/hydra/guix-modular.scm
+++ b/build-aux/hydra/guix-modular.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -21,35 +21,14 @@
 ;;; Guix as 'guix pull', which is defined in (guix self).
 ;;;
 
-;; Attempt to use our very own Guix modules.
-(eval-when (compile load eval)
-
-  ;; Ignore any available .go, and force recompilation.  This is because our
-  ;; checkout in the store has mtime set to the epoch, and thus .go files look
-  ;; newer, even though they may not correspond.
-  (set! %fresh-auto-compile #t)
-
-  (and=> (assoc-ref (current-source-location) 'filename)
-         (lambda (file)
-           (let ((dir (canonicalize-path
-                       (string-append (dirname file) "/../.."))))
-             (format (current-error-port) "prepending ~s to the load path~%"
-                     dir)
-             (set! %load-path (cons dir %load-path))))))
-
-
 (use-modules (guix store)
              (guix config)
              (guix utils)
-             (guix grafts)
              ((guix packages) #:select (%hydra-supported-systems))
              (guix derivations)
              (guix monads)
-             (guix gexp)
-             (guix self)
              ((guix licenses) #:prefix license:)
              (srfi srfi-1)
-             (srfi srfi-26)
              (ice-9 match))
 
 ;; XXX: Debugging hack: since `hydra-eval-guile-jobs' redirects the output
@@ -61,11 +40,13 @@
   "Return a Hydra job a list building the modular Guix derivation from SOURCE
 for SYSTEM.  Use VERSION as the version identifier."
   (lambda ()
+    (define build
+      (primitive-load (string-append source "/build-aux/build-self.scm")))
+
     `((derivation . ,(derivation-file-name
-                      (parameterize ((%graft? #f))
-                        (run-with-store store
-                          (lower-object (compiled-guix source
-                                                       #:version version))))))
+                      (run-with-store store
+                        (build source #:version version #:system system
+                               #:guile-version "2.2")))) ;the latest 2.2.x
       (description . "Modular Guix")
       (long-description
        . "This is the modular Guix package as produced by 'guix pull'.")
@@ -76,29 +57,26 @@ for SYSTEM.  Use VERSION as the version identifier."
 (define (hydra-jobs store arguments)
   "Return Hydra jobs."
   (define systems
-    (match (filter-map (match-lambda
-                         (('system . value) value)
-                         (_ #f))
-                       arguments)
-      ((lst ..1)
-       lst)
-      (_
-       (list (%current-system)))))
+    (match (assoc-ref arguments 'systems)
+      (#f              %hydra-supported-systems)
+      ((lst ...)       lst)
+      ((? string? str) (call-with-input-string str read))))
 
   (define guix-checkout
-    (assq-ref arguments 'guix))
+    (or (assq-ref arguments 'guix)                ;Hydra on hydra
+        (assq-ref arguments 'guix-modular)))      ;Cuirass on berlin
 
   (define version
     (or (assq-ref guix-checkout 'revision)
         "0.unknown"))
 
   (let ((file (assq-ref guix-checkout 'file-name)))
-    (format (current-error-port) "using checkout ~s (~s)~%"
-            guix-checkout file)
+    (format (current-error-port) "using checkout ~s (~s; arguments: ~s)~%"
+            guix-checkout file arguments)
 
     (map (lambda (system)
            (let ((name (string->symbol
                         (string-append "guix." system))))
              `(,name
                . ,(build-job store file version system))))
-         %hydra-supported-systems)))
+         systems)))
diff --git a/build-aux/hydra/guix.scm b/build-aux/hydra/guix.scm
index 659b8bfbc1..08193ec82e 100644
--- a/build-aux/hydra/guix.scm
+++ b/build-aux/hydra/guix.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -22,7 +22,7 @@
 ;;;
 
 ;; Attempt to use our very own Guix modules.
-(eval-when (compile load eval)
+(eval-when (expand load eval)
 
   ;; Ignore any available .go, and force recompilation.  This is because our
   ;; checkout in the store has mtime set to the epoch, and thus .go files look