From 295af6ab173534e65c53fb4d2e4afff2fc8476c7 Mon Sep 17 00:00:00 2001
From: "Yury G. Kudryashov" <urkud.urkud@gmail.com>
Date: Wed, 14 Apr 2010 19:26:31 +0000
Subject: [PATCH] Ignore fake collisions

svn path=/nixpkgs/trunk/; revision=21075
---
 pkgs/build-support/buildenv/builder.pl | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/pkgs/build-support/buildenv/builder.pl b/pkgs/build-support/buildenv/builder.pl
index 37eb21887fd0..856eca7b80be 100755
--- a/pkgs/build-support/buildenv/builder.pl
+++ b/pkgs/build-support/buildenv/builder.pl
@@ -1,7 +1,7 @@
 #! @perl@ -w
 
 use strict;
-use Cwd;
+use Cwd 'abs_path';
 use IO::Handle;
 use File::Path;
 use File::Basename;
@@ -96,9 +96,17 @@ sub createLinks {
         }
 
         elsif (-l $dstFile) {
-            if (!$ignoreCollisions) {
-                my $target = readlink $dstFile;
-                die "collission between `$srcFile' and `$target'";
+            my $oldTarget = readlink $dstFile;
+            my $oldTargetReal = abs_path $oldTarget;
+            my $newTarget = $srcFile;
+            my $newTargetReal = abs_path $newTarget;
+            unless ($newTargetReal eq $oldTargetReal) {
+                if ($ignoreCollisions) {
+                    warn "collision between `$newTarget' and `$oldTarget'\n";
+                }
+                else {
+                    die "collision between `$newTarget' and `$oldTarget'";
+                }
             }
         }
 
@@ -114,7 +122,7 @@ my %done;
 my %postponed;
 
 sub addPkg;
-sub addPkg {
+sub addPkg($;$) {
     my $pkgDir = shift;
     my $ignoreCollisions = shift;
 
@@ -131,6 +139,7 @@ sub addPkg {
         close PROP;
         my @propagated = split ' ', $propagated;
         foreach my $p (@propagated) {
+            print "$pkgDir propagates $p\n";
             $postponed{$p} = 1 unless defined $done{$p};
         }
     }