Bug #1163325: "special" decimals aren't hashable

Lib/decimal.py

@@ -728,6 +728,10 @@ class Decimal(object):
         # Decimal integers must hash the same as the ints
         # Non-integer decimals are normalized and hashed as strings
         # Normalization assures that hast(100E-1) == hash(10)
+        if self._is_special:
+            if self._isnan():
+                raise TypeError('Cannot hash a NaN value.')
+            return hash(str(self))
         i = int(self)
         if self == Decimal(i):
             return hash(i)

Lib/test/test_decimal.py

@@ -811,6 +811,9 @@ class DecimalUsabilityTest(unittest.TestCase):
         hash(Decimal(23))
         #the same hash that to an int
         self.assertEqual(hash(Decimal(23)), hash(23))
+        self.assertRaises(TypeError, hash, Decimal('NaN'))
+        self.assert_(hash(Decimal('Inf')))
+        self.assert_(hash(Decimal('-Inf')))
 
     def test_min_and_max_methods(self):
 

Misc/NEWS

@@ -86,6 +86,9 @@ Extension Modules
 Library
 -------
 
+- Bug #1163325:  Decimal infinities failed to hash.  Attempting to
+  hash a NaN raised an InvalidOperation instead of a TypeError.
+
 - Patch #918101: Add tarfile open mode r|* for auto-detection of the 
   stream compression; add, for symmetry reasons, r:* as a synonym of r.