union: Detect collisions, and delete duplicate leaves.

* guix/build/union.scm (delete-duplicate-leaves): New procedure.
  (union-build)[leaf=?, resolve-collision]: New procedures.
  Use `delete-duplicate-leaves' on the result of `tree-union'.
* tests/union.scm ("delete-duplicate-leaves, default",
  "delete-duplicate-leaves, file names"): New tests.

1 files changed, 20 insertions, 1 deletions

diff --git a/tests/union.scm b/tests/union.scm
index 317d49dc35e..a3859434a23 100644
--- a/tests/union.scm
+++ b/tests/union.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -64,6 +64,25 @@
                 (bin make)
                 (share (doc (make README))))))
 
+(test-equal "delete-duplicate-leaves, default"
+  '(bin make touch ls)
+  (delete-duplicate-leaves '(bin ls make touch ls)))
+
+(test-equal "delete-duplicate-leaves, file names"
+  '("doc" ("info"
+           "/binutils/ld.info"
+           "/gcc/gcc.info"
+           "/binutils/standards.info"))
+  (let ((leaf=? (lambda (a b)
+                  (string=? (basename a) (basename b)))))
+    (delete-duplicate-leaves '("doc"
+                               ("info"
+                                "/binutils/ld.info"
+                                "/binutils/standards.info"
+                                "/gcc/gcc.info"
+                                "/gcc/standards.info"))
+                             leaf=?)))
+
 (test-skip (if (and %store
                     (false-if-exception
                      (getaddrinfo "www.gnu.org" "80" AI_NUMERICSERV)))