diff -r b7b805e05978 Lib/test/test_peepholer.py
--- a/Lib/test/test_peepholer.py	Wed Mar 09 19:01:04 2011 -0500
+++ b/Lib/test/test_peepholer.py	Thu Mar 10 20:09:07 2011 -0500
@@ -3,6 +3,7 @@
 import sys
 from io import StringIO
 import unittest
+from math import copysign
 
 def disassemble(func):
     f = StringIO()
@@ -267,6 +268,49 @@
         asm = disassemble(f)
         self.assertNotIn('BINARY_ADD', asm)
 
+    def test_dedup_consts_after_fold(self):
+        def mapping(x):
+            # Special handling for -0.0
+            if isinstance(x, float):
+                s = copysign(1.0, x)
+            elif isinstance(x, complex):
+                s = copysign(10.0, x.real) + copysign(1.0, x.imag)
+            else:
+                s = 0
+            return type(x), x, s
+
+        def fix(consts):
+            return len(consts), set(map(mapping, consts))
+
+        def check(f, consts):
+            self.assertEqual(fix(f.__code__.co_consts), fix(consts))
+
+        def const1(): 'doc'; return [1+2, 1+2, 1+2, 1.0+2.0]
+        check(const1, ('doc', 3, 3.0))
+
+        def const2(): return [10000+2, 10000+2, 10000+2, 10000.0+2]
+        check(const2, (None, 10002, 10002.0))
+
+        def const3(): return [1.0*0.0, -1.0*0.0, 2*0.0, -2*0.0]
+        check(const3, (None, 0.0, -0.0))
+
+        def const4(): return [1+0j, 0.5+0.5, 1+0j, 0.5+0.5, 1+0j]
+        check(const4, (None, 1+0j, 1.0))
+
+        def const5():
+            return [0.0j, -0.0j, 0.0, -0.0, 1.0+0j, -(-1.0+0j),
+                    1.0, -(0.0-1.0j), 1j]
+        x = 0.0
+        xj = 0j
+        check(const5,
+              (None, 0j, 0.0, 1.0, 1j, -xj, -0.0, 1+0j, -(-1+xj), -(x-1j)))
+
+        def const6(): 'ab'; return ['a'+'b', 'a'+'b', 'a'+'b']
+        check(const6, ('ab',))
+
+        def const7(): return [(1,2), (1,2)]
+        check(const7, (None, (1,2)))
+
 
 def test_main(verbose=None):
     import sys