gexp: 'gexp-inputs' returns a list of <gexp-input> records.

This slightly reduces memory allocation.

* guix/gexp.scm (lower-inputs): Expect a list of <gexp-input> rather
than a list of tuples.
(lower-reference-graphs)[tuple->gexp-input]: New procedure.
Use it.
(gexp-inputs): Return a list of <gexp-input> rather than a list of
tuples.
* tests/gexp.scm (gexp-input->tuple): New procedure.
("one input package")
("one input package, dotted list")
("one input origin")
("one local file")
("one local file, symlink")
("one plain file")
("two input packages, one derivation, one file")
("file-append")
("file-append, output")
("file-append, nested")
("let-system")
("let-system, nested")
("ungexp + ungexp-native")
("ungexp + ungexp-native, nested")
("ungexp + ungexp-native, nested, special mixture")
("input list")
("input list + ungexp-native")
("input list splicing")
("input list splicing + ungexp-native-splicing")
("gexp list splicing + ungexp-splicing"): Adjust accordingly.

1 files changed, 21 insertions, 16 deletions

diff --git a/guix/gexp.scm b/guix/gexp.scm
index 8dd824c512..8e80d4adbe 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -842,24 +842,23 @@ When TARGET is true, use it as the cross-compilation target triplet."
   (with-monad %store-monad
     (>>= (mapm/accumulate-builds
           (match-lambda
-            (((? struct? thing) sub-drv ...)
-             (mlet %store-monad ((obj (lower-object
-                                       thing system #:target target)))
+            (($ <gexp-input> (? store-item? item))
+             (return item))
+            (($ <gexp-input> thing output native?)
+             (mlet %store-monad ((obj (lower-object thing system
+                                                    #:target
+                                                    (and (not native?)
+                                                         target))))
                (return (match obj
                          ((? derivation? drv)
-                          (let ((outputs (if (null? sub-drv)
-                                             '("out")
-                                             sub-drv)))
-                            (derivation-input drv outputs)))
+                          (derivation-input drv (list output)))
                          ((? store-item? item)
                           item)
                          ((? self-quoting?)
                           ;; Some inputs such as <system-binding> can lower to
                           ;; a self-quoting object that FILTERM will filter
                           ;; out.
-                          #f)))))
-            (((? store-item? item))
-             (return item)))
+                          #f))))))
           inputs)
          filterm)))
 
@@ -867,9 +866,16 @@ When TARGET is true, use it as the cross-compilation target triplet."
   "Given GRAPHS, a list of (FILE-NAME INPUT ...) lists for use as a
 #:reference-graphs argument, lower it such that each INPUT is replaced by the
 corresponding <derivation-input> or store item."
+  (define tuple->gexp-input
+    (match-lambda
+      ((thing)
+       (%gexp-input thing "out" #t))
+      ((thing output)
+       (%gexp-input thing output #t))))
+
   (match graphs
     (((file-names . inputs) ...)
-     (mlet %store-monad ((inputs (lower-inputs inputs
+     (mlet %store-monad ((inputs (lower-inputs (map tuple->gexp-input inputs)
                                                #:system system
                                                #:target target)))
        (return (map cons file-names inputs))))))
@@ -1213,9 +1219,8 @@ The other arguments are as for 'derivation'."
                       #:properties properties))))
 
 (define* (gexp-inputs exp #:key native?)
-  "Return the input list for EXP.  When NATIVE? is true, return only native
-references; otherwise, return only non-native references."
-  ;; TODO: Return <gexp-input> records instead of tuples.
+  "Return the list of <gexp-input> for EXP.  When NATIVE? is true, return only
+native references; otherwise, return only non-native references."
   (define (add-reference-inputs ref result)
     (match ref
       (($ <gexp-input> (? gexp? exp) _ #t)
@@ -1229,12 +1234,12 @@ references; otherwise, return only non-native references."
                result))
       (($ <gexp-input> (? string? str))
        (if (direct-store-path? str)
-           (cons `(,str) result)
+           (cons ref result)
            result))
       (($ <gexp-input> (? struct? thing) output n?)
        (if (and (eqv? n? native?) (lookup-compiler thing))
            ;; THING is a derivation, or a package, or an origin, etc.
-           (cons `(,thing ,output) result)
+           (cons ref result)
            result))
       (($ <gexp-input> (lst ...) output n?)
        (fold-right add-reference-inputs result