02/02: build-system/haskell: Fix regression in "cabal-revision" input handling.

[guix-commits]

civodul pushed a commit to branch core-updates
in repository guix.

commit a0f880afea3b29e817866de0170ed579738db2d1
Author: Ludovic Courtès <ludo@gnu.org>
AuthorDate: Tue Jul 27 15:04:41 2021 +0200

    build-system/haskell: Fix regression in "cabal-revision" input handling.
    
    Previously, (assoc-ref ...) would return a one-element list, leading to
    an evaluation error while building the package ("wrong type to apply").
    
    Regression introduced in 7d873f194ca69d6096d28d7a224ab78e83e34fe1.
    
    Reported by Marius Bakke.
    
    * guix/build-system/haskell.scm (haskell-build)[builder]: Adjust
    argument to #:cabal-revision.
---
 guix/build-system/haskell.scm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/guix/build-system/haskell.scm b/guix/build-system/haskell.scm
index bd5a6ee..bd4a732 100644
--- a/guix/build-system/haskell.scm
+++ b/guix/build-system/haskell.scm
@@ -147,7 +147,15 @@ provides a 'Setup.hs' file as its build system."
           #$(with-build-variables inputs outputs
               #~(haskell-build #:name #$name
                                #:source #+source
-                               #:cabal-revision #$(assoc-ref inputs 
"cabal-revision")
+
+                               ;; XXX: INPUTS contains <gexp-input> records as
+                               ;; opposed to raw lowerable objects, hence the
+                               ;; use of ungexp-splicing.
+                               #:cabal-revision
+                               #$@(match (assoc-ref inputs "cabal-revision")
+                                    (#f '())
+                                    (lst lst))
+
                                #:configure-flags #$configure-flags
                                #:extra-directories #$extra-directories
                                #:extra-directories #$extra-directories