[bug#61420] [PATCH 11/31] build: haskell-build-system: Process all transitive dependencies.

[Lars-Dominik Braun]

A bug caused install-transitive-deps to stop looping if a dependency
file already existed in the target directory. For Haskell packages
with multiple libraries (like attoparsec) this resulted in missing
dependencies and error messages like this:

    The following packages are broken because other packages they depend
    on are missing. These broken packages must be rebuilt before they
    can be used.
    installed package attoparsec-0.14.4 is broken due to missing package
    scientific-0.3.7.0-9XG3zUjXOw970JFcruv0cZ

See <https://issues.guix.gnu.org/54729#11>.

* guix/build/haskell-build-system.scm (register): Unconditionally loop
over all tails.
---
 guix/build/haskell-build-system.scm | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/guix/build/haskell-build-system.scm 
b/guix/build/haskell-build-system.scm
index fb4aba28ea..72e12ba746 100644
--- a/guix/build/haskell-build-system.scm
+++ b/guix/build/haskell-build-system.scm
@@ -214,14 +214,16 @@ (define (install-transitive-deps conf-file src dest)
         (() #t)                         ;done
         ((id . tail)
          (if (not (vhash-assoc id seen))
-             (let ((dep-conf  (string-append src  "/" id ".conf"))
-                   (dep-conf* (string-append dest "/" id ".conf")))
-               (unless (file-exists? dep-conf*)
-                 (unless (file-exists? dep-conf)
+             (let* ((dep-conf  (string-append src  "/" id ".conf"))
+                    (dep-conf* (string-append dest "/" id ".conf"))
+                    (dep-conf-exists? (file-exists? dep-conf))
+                    (dep-conf*-exists? (file-exists? dep-conf*))
+                    (next-tail (append lst (if dep-conf-exists? (conf-depends 
dep-conf) '()))))
+               (unless dep-conf*-exists?
+                 (unless dep-conf-exists?
                    (error (format #f "File ~a does not exist. This usually 
means the dependency ~a is missing. Was checking conf-file ~a." dep-conf id 
conf-file)))
-                 (copy-file dep-conf dep-conf*) ;XXX: maybe symlink instead?
-                 (loop (vhash-cons id #t seen)
-                       (append lst (conf-depends dep-conf)))))
+                 (copy-file dep-conf dep-conf*)) ;XXX: maybe symlink instead?
+                (loop (vhash-cons id #t seen) next-tail))
              (loop seen tail))))))
 
   (define (install-config-file conf-file dest output:doc output:lib)
-- 
2.38.2