From 53297b1441539efdc44fc9c8f4f19fb6ba8290c9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
Date: Thu, 21 Nov 2013 12:03:32 +0100
Subject: [PATCH] Fix setting undefined variable in CSH
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<https://rt.cpan.org/Public/Bug/Display.html?id=85667>

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 lib/local/lib.pm | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/local/lib.pm b/lib/local/lib.pm
index 289e13b..d4f8e2a 100644
--- a/lib/local/lib.pm
+++ b/lib/local/lib.pm
@@ -343,7 +343,24 @@ sub build_bourne_env_declaration {
 sub build_csh_env_declaration {
   my $class = shift;
   my($name, $value) = @_;
-  return defined($value) ? qq{setenv ${name} "${value}";\n} : qq{unsetenv ${name};\n};
+  if (defined($value)) {
+    if ($value =~ /(.*)(\A|\Q$Config{path_sep}\E)(\$)(.+?)(\z|\Q$Config{path_sep}\E)(.*)/) {
+      # If a variable reference exists in the value, we have to delimit it and
+      # dereference it only if it is defined.
+      return
+        qq{test 1 == \$\{?$4\} && } .
+        qq{setenv ${name} "${1}${2}${3}\{${4}\}${5}${6}"} .
+        qq{ || } .
+        qq{setenv ${name} "${1}} .
+          (($2 ne '' and $5 ne '') ?  qq{${2}} : '') .
+          qq{${6}"} .
+        qq{;\n};
+    } else {
+        return qq{setenv ${name} "${value}";\n};
+    }
+  } else {
+    return qq{unsetenv ${name};\n};
+  }
 }
 
 sub build_win32_env_declaration {
-- 
1.8.3.1