Fix Decimal hash in Python 2.5 maintenance branch so that hash(x) == hash(int(x))
for any integral Decimal instance x.
diff --git a/Lib/decimal.py b/Lib/decimal.py
index 3ee078f..ebeb6d7 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -800,13 +800,7 @@
return 0
if self._isinteger():
op = _WorkRep(self.to_integral_value())
- # to make computation feasible for Decimals with large
- # exponent, we use the fact that hash(n) == hash(m) for
- # any two nonzero integers n and m such that (i) n and m
- # have the same sign, and (ii) n is congruent to m modulo
- # 2**64-1. So we can replace hash((-1)**s*c*10**e) with
- # hash((-1)**s*c*pow(10, e, 2**64-1).
- return hash((-1)**op.sign*op.int*pow(10, op.exp, 2**64-1))
+ return hash((-1)**op.sign*op.int*10**op.exp)
# The value of a nonzero nonspecial Decimal instance is
# faithfully represented by the triple consisting of its sign,
# its adjusted exponent, and its coefficient with trailing
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index 46a448b..34fc34a 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -961,6 +961,16 @@
# a value for which hash(n) != hash(n % (2**64-1))
# in Python pre-2.6
Decimal(2**64 + 2**32 - 1),
+ # selection of values which fail with the Python 2.6
+ # version of Decimal.__hash__ and the Python 2.5
+ # version of long.__hash__. Included here to prevent
+ # an accidental backport of the Decimal.__hash__ from
+ # Python 2.6 to Python 2.5.
+ Decimal("1.634E100"),
+ Decimal("90.697E100"),
+ Decimal("188.83E100"),
+ Decimal("1652.9E100"),
+ Decimal("56531E100"),
])
# check that hash(d) == hash(int(d)) for integral values