From: Mark Dickinson <dickinsm@gmail.com>
Date: Sun, 8 Feb 2009 14:42:28 +0000 (+0000)
Subject: Issue #789290: make sure that hash(2**63) == hash(2.**63) on 64-bit
X-Git-Tag: v2.7a1~2076
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=10fe877dcd547befa3114e52f180bacf98e56098;p=python

Issue #789290: make sure that hash(2**63) == hash(2.**63) on 64-bit
platforms.  The previous code was fragile, depending on the twin
accidents that:

  (1) in C, casting the double value 2.**63 to long returns the integer
      value -2**63, and
  (2) in Python, hash(-2**63) == hash(2**63).

There's already a test for this in test_hash.
---

diff --git a/Objects/object.c b/Objects/object.c
index ba736a9d93..9108fd431a 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1028,7 +1028,7 @@ _Py_HashDouble(double v)
 	fractpart = modf(v, &intpart);
 	if (fractpart == 0.0) {
 		/* This must return the same hash as an equal int or long. */
-		if (intpart > LONG_MAX || -intpart > LONG_MAX) {
+		if (intpart > LONG_MAX/2 || -intpart > LONG_MAX/2) {
 			/* Convert to long and use its hash. */
 			PyObject *plong;	/* converted to Python long */
 			if (Py_IS_INFINITY(intpart))