[Python-checkins] r69436 - python/trunk/Objects/object.c

[mark.dickinson]

Author: mark.dickinson
Date: Sun Feb  8 15:42:28 2009
New Revision: 69436

Log:
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.


Modified:
   python/trunk/Objects/object.c

Modified: python/trunk/Objects/object.c
==============================================================================
--- python/trunk/Objects/object.c	(original)
+++ python/trunk/Objects/object.c	Sun Feb  8 15:42:28 2009
@@ -1028,7 +1028,7 @@
 	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))