From cd2f7ce9f9f10894c6d2a5995f06fb9d2a7f6795 Mon Sep 17 00:00:00 2001
From: "Nicolas B. Pierron" <nicolas.b.pierron@gmail.com>
Date: Fri, 19 Dec 2014 23:00:52 +0100
Subject: [PATCH] nixos-option: Improve error messages to avoid reporting
 internal location and traces.

---
 nixos/modules/installer/tools/nixos-option.sh | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/installer/tools/nixos-option.sh b/nixos/modules/installer/tools/nixos-option.sh
index b5f69f07826c..4478059813d1 100644
--- a/nixos/modules/installer/tools/nixos-option.sh
+++ b/nixos/modules/installer/tools/nixos-option.sh
@@ -69,7 +69,18 @@ fi
 #############################
 
 evalNix(){
-  nix-instantiate - --eval-only "$@"
+  result=$(nix-instantiate - --eval-only "$@" 2>&1)
+  if test $? -eq 0; then
+      cat <<EOF
+$result
+EOF
+      return 0;
+  else
+      sed -n '/error/ { s/, at (string):[0-9]*:[0-9]*//; p; }' <<EOF
+$result
+EOF
+      return 1;
+  fi
 }
 
 evalAttr(){