From dee13c7fd4fadacc9c95a4d984e0ca97da9e3d1b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Domen=20Ko=C5=BEar?= <domen@dev.si>
Date: Mon, 30 May 2016 12:34:03 +0100
Subject: doc: mention overrideDerivation causes evaluation of Derivation

---
 doc/functions.xml | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'doc')

diff --git a/doc/functions.xml b/doc/functions.xml
index 7d250824f785..e6bb6b7deefb 100644
--- a/doc/functions.xml
+++ b/doc/functions.xml
@@ -92,7 +92,14 @@ in ...</programlisting>
     <para>Do not use this function in Nixpkgs. Because it breaks
     package abstraction and doesn’t provide error checking for
     function arguments, it is only intended for ad-hoc customisation
-    (such as in <filename>~/.nixpkgs/config.nix</filename>).</para>
+    (such as in <filename>~/.nixpkgs/config.nix</filename>).
+   </para>
+
+   <para>
+    Additionally, <varname>overrideDerivation</varname> forces an evaluation
+    of the Derivation which can be quite a performance penalty if there are many
+    overrides used.
+   </para>
   </warning>
 
   <para>
-- 
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