build: Expand ‘scripts/guix’ at Make time.

This moves the complexity of Autotools variable expansion outside of the
application code.

* scripts/guix.in (config-lookup): Delete.
(maybe-augment-load-paths!, run-guix-main): Use fully expanded variables
instead of calling ‘config-lookup’.
* configure.ac: Don't use AC_CONFIG_FILES for ‘scripts/guix’.
Use AC_PROG_SED.
* Makefile.am (scripts/guix): New rule.
(do_subst): New variable.
(CLEANFILES, EXTRA_DIST): Adapt.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

Makefile.am

@@ -2,7 +2,7 @@
 # Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
 # Copyright © 2013 Andreas Enge <andreas@enge.fr>
 # Copyright © 2015, 2017 Alex Kost <alezost@gmail.com>
-# Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
+# Copyright © 2016, 2018 Mathieu Lirzin <mthl@gnu.org>
 # Copyright © 2016, 2017 Mark H Weaver <mhw@netris.org>
 # Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 # Copyright © 2017 Leo Famulari <leo@famulari.name>
@@ -26,8 +26,20 @@
 # You should have received a copy of the GNU General Public License
 # along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
-bin_SCRIPTS =					\
-  scripts/guix
+bin_SCRIPTS = scripts/guix
+
+# Handle substitution of fully-expanded Autoconf variables.
+do_subst = $(SED)					\
+  -e 's,[@]GUILE[@],$(GUILE),g'				\
+  -e 's,[@]guilemoduledir[@],$(guilemoduledir),g'	\
+  -e 's,[@]guileobjectdir[@],$(guileobjectdir),g'	\
+  -e 's,[@]localedir[@],$(localedir),g'
+
+scripts/guix: scripts/guix.in Makefile
+	$(AM_V_at)rm -f $@ $@-t
+	$(AM_V_at)$(MKDIR_P) "$(@D)"
+	$(AM_V_GEN)$(do_subst) < "$(srcdir)/$@.in" > "$@-t"
+	$(AM_V_at)chmod a+x,a-w "$@-t" && mv -f "$@-t" "$@"
 
 nodist_noinst_SCRIPTS =				\
   pre-inst-env					\
@@ -437,6 +449,7 @@ EXTRA_DIST =						\
   TODO							\
   CODE-OF-CONDUCT					\
   .dir-locals.el					\
+  bin/guix.in						\
   build-aux/build-self.scm				\
   build-aux/compile-all.scm				\
   build-aux/hydra/evaluate.scm				\
@@ -473,6 +486,7 @@ endif !BUILD_DAEMON_OFFLOAD
 
 
 CLEANFILES =					\
+  $(bin_SCRIPTS)				\
   $(GOBJECTS)					\
   $(SCM_TESTS:tests/%.scm=%.log)
 

configure.ac

@@ -124,6 +124,8 @@ dnl Make sure we don't suffer from the bug in 'equal?' wrt. syntax objects
 dnl found in 2.2.1.  See <https://bugs.gnu.org/29903>.
 GUIX_ASSERT_SYNTAX_OBJECT_EQUAL
 
+AC_PROG_SED
+
 dnl Decompressors, for use by the substituter and other modules.
 AC_PATH_PROG([GZIP], [gzip])
 AC_PATH_PROG([BZIP2], [bzip2])
@@ -272,7 +274,6 @@ AC_CONFIG_FILES([Makefile
                  po/packages/Makefile.in
 		 guix/config.scm])
 
-AC_CONFIG_FILES([scripts/guix], [chmod +x scripts/guix])
 AC_CONFIG_FILES([test-env:build-aux/test-env.in], [chmod +x test-env])
 AC_CONFIG_FILES([pre-inst-env:build-aux/pre-inst-env.in],
   [chmod +x pre-inst-env])

scripts/guix.in

@@ -3,6 +3,7 @@
 !#
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2018 Mathieu Lirzin <mthl@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -22,35 +23,15 @@
 ;; IMPORTANT: We must avoid loading any modules from Guix here,
 ;; because we need to adjust the guile load paths first.
 ;; It's okay to import modules from core Guile though.
-(use-modules (ice-9 regex)
-             (srfi srfi-26))
+(use-modules (srfi srfi-26))
 
 (let ()
   (define-syntax-rule (push! elt v) (set! v (cons elt v)))
 
-  (define config-lookup
-    (let ((config '(("prefix"         . "@prefix@")
-                    ("exec_prefix"    . "@exec_prefix@")
-                    ("datarootdir"    . "@datarootdir@")
-                    ("guilemoduledir" . "@guilemoduledir@")
-                    ("guileobjectdir" . "@guileobjectdir@")
-                    ("localedir"      . "@localedir@")))
-          (var-ref-regexp (make-regexp "\\$\\{([a-z_]+)\\}")))
-      (define (expand-var-ref match)
-        (lookup (match:substring match 1)))
-      (define (expand str)
-        (regexp-substitute/global #f var-ref-regexp str
-                                  'pre expand-var-ref 'post))
-      (define (lookup name)
-        (expand (assoc-ref config name)))
-      lookup))
-
   (define (maybe-augment-load-paths!)
     (unless (getenv "GUIX_UNINSTALLED")
-      (let ((module-dir (config-lookup "guilemoduledir"))
-            (object-dir (config-lookup "guileobjectdir")))
-        (push! module-dir %load-path)
-        (push! object-dir %load-compiled-path))
+      (push! "@guilemoduledir@" %load-path)
+      (push! "@guileobjectdir@" %load-compiled-path)
       (let ((updates-dir (and=> (or (getenv "XDG_CONFIG_HOME")
                                     (and=> (getenv "HOME")
                                            (cut string-append <> "/.config")))
@@ -64,8 +45,8 @@
   (define (run-guix-main)
     (let ((guix-main (module-ref (resolve-interface '(guix ui))
                                  'guix-main)))
-      (bindtextdomain "guix" (config-lookup "localedir"))
-      (bindtextdomain "guix-packages" (config-lookup "localedir"))
+      (bindtextdomain "guix" "@localedir@")
+      (bindtextdomain "guix-packages" "@localedir@")
       (apply guix-main (command-line))))
 
   (maybe-augment-load-paths!)