build: Remove checks for 'nix-instantiate'.

* guix/import/snix.scm (open-nixpkgs): Use "nix-instantiate"
unconditionally.
* configure.ac: Remove check for 'nix-instantiate'.
* guix/config.scm.in (%nix-instantiate): Remove.
* guix/self.scm (%dependency-variables): Remove '%nix-instantiate'.
(make-config.scm): Remove it from the generated "config.scm".
* build-aux/build-self.scm (%dependency-variables, make-config.scm):
Likewise.

build-aux/build-self.scm

@@ -53,7 +53,7 @@ (define-module (build-self)
 
 (define %dependency-variables
   ;; (guix config) variables corresponding to dependencies.
-  '(%libgcrypt %libz %xz %gzip %bzip2 %nix-instantiate))
+  '(%libgcrypt %libz %xz %gzip %bzip2))
 
 (define %persona-variables
   ;; (guix config) variables that define Guix's persona.
@@ -94,8 +94,7 @@ (define defmod 'define-module)
                                %libz
                                %gzip
                                %bzip2
-                               %xz
-                               %nix-instantiate))
+                               %xz))
 
                    ;; XXX: Work around <http://bugs.gnu.org/15602>.
                    (eval-when (expand load eval)
@@ -121,10 +120,7 @@ (define %libgcrypt
                               (file-append libgcrypt "/lib/libgcrypt")))
                      (define %libz
                        #+(and zlib
-                              (file-append zlib "/lib/libz")))
-
-                     (define %nix-instantiate     ;for (guix import snix)
-                       "nix-instantiate")))))
+                              (file-append zlib "/lib/libz")))))))
 
 
 ;;;

configure.ac

@@ -160,18 +160,11 @@ AC_ARG_WITH([nix-prefix],
    esac],
   [])
 
-AC_PATH_PROG([NIX_INSTANTIATE], [nix-instantiate])
 AC_PATH_PROG([NIX_HASH], [nix-hash])
-if test "x$guix_build_daemon$NIX_INSTANTIATE$NIX_HASH" = "xno"; then
+if test "x$guix_build_daemon$NIX_HASH" = "xno"; then
    AC_MSG_ERROR([Nix programs not found; please install Nix or use `--with-nix-prefix'.])
 fi
 
-if test "x$NIX_INSTANTIATE" = "x"; then
-   # This program is an optional dependency, so we just want it to be
-   # taken from $PATH if it's not available right now.
-   NIX_INSTANTIATE="nix-instantiate"
-fi
-
 AC_ARG_WITH([nixpkgs],
   [AS_HELP_STRING([--with-nixpkgs=DIR],
     [search for Nixpkgs in DIR (for testing purposes only)])],

guix/config.scm.in

@@ -35,7 +35,6 @@ (define-module (guix config)
             %system
             %libgcrypt
             %libz
-            %nix-instantiate
             %gzip
             %bzip2
             %xz))
@@ -95,9 +94,6 @@ (define %libgcrypt
 (define %libz
   "@LIBZ@")
 
-(define %nix-instantiate
-  "@NIX_INSTANTIATE@")
-
 (define %gzip
   "@GZIP@")
 

guix/import/snix.scm

@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -283,7 +283,7 @@ (define* (open-nixpkgs nixpkgs #:optional attribute)
   platform = (import ~a/pkgs/top-level/platforms.nix).sheevaplug;
 }" nixpkgs)))
       (apply open-pipe* OPEN_READ
-             %nix-instantiate "--strict" "--eval-only" "--xml"
+             "nix-instantiate" "--strict" "--eval-only" "--xml"
 
              ;; Pass a dummy `crossSystem' argument so that `buildInputs' and
              ;; `nativeBuildInputs' are not coalesced.

guix/self.scm

@@ -655,7 +655,7 @@ (define (built-modules node-subset)
 
 (define %dependency-variables
   ;; (guix config) variables corresponding to dependencies.
-  '(%libgcrypt %libz %xz %gzip %bzip2 %nix-instantiate))
+  '(%libgcrypt %libz %xz %gzip %bzip2))
 
 (define %persona-variables
   ;; (guix config) variables that define Guix's persona.
@@ -696,8 +696,7 @@ (define defmod 'define-module)
                                %libz
                                %gzip
                                %bzip2
-                               %xz
-                               %nix-instantiate))
+                               %xz))
 
                    #$@(map (match-lambda
                              ((name . value)
@@ -721,13 +720,10 @@ (define %libgcrypt
                             (file-append libgcrypt "/lib/libgcrypt")))
                    (define %libz
                      #+(and zlib
-                            (file-append zlib "/lib/libz")))
-
-                   (define %nix-instantiate       ;for (guix import snix)
-                     "nix-instantiate"))
+                            (file-append zlib "/lib/libz"))))
 
                ;; Guile 2.0 *requires* the 'define-module' to be at the
-               ;; top-level or it 'toplevel-ref' in the resulting .go file are
+               ;; top-level or the 'toplevel-ref' in the resulting .go file are
                ;; made relative to a nonexistent anonymous module.
                #:splice? #t))