gexp: 'lowered-gexp-guile' now returns a <derivation-input>.

* guix/derivations.scm (derivation-input-output-path): New procedure.
* guix/gexp.scm (lower-gexp): Wrap GUILE in a <derivation-input>.
(gexp->derivation): Adjust accordingly.
* guix/remote.scm (remote-pipe-for-gexp, remote-eval): Adjust
accordingly.
* tests/gexp.scm ("lower-gexp"): Adjust accordingly.

4 files changed, 16 insertions, 7 deletions

diff --git a/guix/derivations.scm b/guix/derivations.scm
index 23d058e832..92d50503ce 100644
--- a/guix/derivations.scm
+++ b/guix/derivations.scm
@@ -71,6 +71,7 @@
             derivation-input-derivation
             derivation-input-sub-derivations
             derivation-input-output-paths
+            derivation-input-output-path
             valid-derivation-input?
 
             &derivation-error
@@ -221,6 +222,13 @@ download with a fixed hash (aka. `fetchurl')."
      (map (cut derivation->output-path drv <>)
           sub-drvs))))
 
+(define (derivation-input-output-path input)
+  "Return the output file name of INPUT.  If INPUT has more than one outputs,
+an error is raised."
+  (match input
+    (($ <derivation-input> drv (output))
+     (derivation->output-path drv output))))
+
 (define (valid-derivation-input? store input)
   "Return true if INPUT is valid--i.e., if all the outputs it requests are in
 the store."
diff --git a/guix/gexp.scm b/guix/gexp.scm
index 52643bd684..eef308b000 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -648,7 +648,7 @@ names and file names suitable for the #:allowed-references argument to
   (sexp                lowered-gexp-sexp)         ;sexp
   (inputs              lowered-gexp-inputs)       ;list of <derivation-input>
   (sources             lowered-gexp-sources)      ;list of store items
-  (guile               lowered-gexp-guile)        ;<derivation> | #f
+  (guile               lowered-gexp-guile)        ;<derivation-input> | #f
   (load-path           lowered-gexp-load-path)    ;list of store items
   (load-compiled-path  lowered-gexp-load-compiled-path)) ;list of store items
 
@@ -755,7 +755,7 @@ derivations--e.g., code evaluated for its side effects."
                               ,@(map derivation-input exts)
                               ,@(filter derivation-input? inputs))
                             (filter string? (cons modules inputs))
-                            guile
+                            (derivation-input guile '("out"))
                             load-path
                             load-compiled-path)))))
 
@@ -889,7 +889,7 @@ The other arguments are as for 'derivation'."
     (mbegin %store-monad
       (set-grafting graft?)                       ;restore the initial setting
       (raw-derivation name
-                      (string-append (derivation->output-path guile)
+                      (string-append (derivation-input-output-path guile)
                                      "/bin/guile")
                       `("--no-auto-compile"
                         ,@(append-map (lambda (directory)
@@ -902,7 +902,7 @@ The other arguments are as for 'derivation'."
                       #:outputs outputs
                       #:env-vars env-vars
                       #:system system
-                      #:inputs `(,(derivation-input guile '("out"))
+                      #:inputs `(,guile
                                  ,@(lowered-gexp-inputs lowered)
                                  ,@(match graphs
                                      (((_ . inputs) ...)
diff --git a/guix/remote.scm b/guix/remote.scm
index 52ced16871..d49ee91b38 100644
--- a/guix/remote.scm
+++ b/guix/remote.scm
@@ -46,7 +46,7 @@
     (compose object->string object->string))
 
   (apply open-remote-pipe* session OPEN_READ
-         (string-append (derivation->output-path
+         (string-append (derivation-input-output-path
                          (lowered-gexp-guile lowered))
                         "/bin/guile")
          "--no-auto-compile"
@@ -95,7 +95,7 @@ remote store."
                       (remote -> (connect-to-remote-daemon session
                                                            socket-name)))
     (define inputs
-      (cons (derivation-input (lowered-gexp-guile lowered))
+      (cons (lowered-gexp-guile lowered)
             (lowered-gexp-inputs lowered)))
 
     (define sources
diff --git a/tests/gexp.scm b/tests/gexp.scm
index a1f79e3435..460afe7f59 100644
--- a/tests/gexp.scm
+++ b/tests/gexp.scm
@@ -868,7 +868,8 @@
                             "/lib/guile/2.0/site-ccache")
                            (lowered-gexp-load-compiled-path lexp))
                    (= 2 (length (lowered-gexp-load-compiled-path lexp)))
-                   (eq? (lowered-gexp-guile lexp) (%guile-for-build)))))))
+                   (eq? (derivation-input-derivation (lowered-gexp-guile lexp))
+                        (%guile-for-build)))))))
 
 (test-assertm "gexp->derivation #:references-graphs"
   (mlet* %store-monad