From 82ba13111c72937b792edd40bcbebbda1d395c7c Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Tue, 12 May 2015 06:26:31 -0700
Subject: [PATCH] ncurses: Fix shouldUsePkg on darwin

---
 pkgs/development/libraries/ncurses/default.nix | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/libraries/ncurses/default.nix b/pkgs/development/libraries/ncurses/default.nix
index 051d29924dfc..fd545e53625f 100644
--- a/pkgs/development/libraries/ncurses/default.nix
+++ b/pkgs/development/libraries/ncurses/default.nix
@@ -16,7 +16,11 @@ let
   mkWith = mkFlag "with-" "without-";
   mkOther = mkFlag "" "" true;
 
-  shouldUsePkg = pkg: if pkg != null && stdenv.lib.any (x: x == stdenv.system) pkg.meta.platforms then pkg else null;
+  shouldUsePkg = pkg_: let
+    pkg = (builtins.tryEval pkg_).value;
+  in if stdenv.lib.any (x: x == stdenv.system) (pkg.meta.platforms or [])
+    then pkg
+    else null;
 
   buildShared = !stdenv.isDarwin;