From db90b88e655a0d8e501beddee966a124b2f097d8 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Mon, 12 Apr 2010 09:50:20 +0000
Subject: [PATCH] * Hack to support builderDefs expressions.

---
 src/libexpr/eval.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 02f5e3dc8d..7434aa8422 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -918,8 +918,14 @@ bool EvalState::eqValues(Value & v1, Value & v2)
     forceValue(v1);
     forceValue(v2);
 
+    /* !!! Hack to support some old broken code that relies on pointer
+       equality tests between attribute sets.  (Specifically,
+       builderDefs calls uniqList on a list of attribute sets.)  Will
+       remove this eventually. */
+    if (&v1 == &v2) return true;
+
     if (v1.type != v2.type) return false;
-    
+
     switch (v1.type) {
 
         case tInt: