[Python-bugs-list] [ python-Bugs-689659 ] 64-bit int and long hash keys incompatible

[SourceForge.net]

Bugs item #689659, was opened at 2003-02-19 23:17
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=689659&group_id=5470

Category: Python Interpreter Core
Group: Platform-specific
Status: Open
Resolution: None
Priority: 5
Submitted By: Mark Dickinson (marketdickinson)
Assigned to: Nobody/Anonymous (nobody)
Summary: 64-bit int and long hash keys incompatible

Initial Comment:
For 64-bit platforms, it seems that ints and longs with the 
same value don't necessarily give the same hash key.  
An example is below; the phenomenon seems to occur 
for a range of numbers between 2**32 and 2**64. 
 
I assume this is unintentional?  It looks suspiciously as 
though the function long_hash in Objects/longobject.c 
has 32-bitness hard-coded. Lines 1288-1289 of that file 
in the Python 2.2.2 source read: 
 
      /* Force a 32-bit circular shift */ 
      x = ((x << SHIFT) & ~MASK) | ((x >> (32-SHIFT)) & 
MASK); 
 
And here's the Python example: 
 
Python 2.2.2 (#22, Dec 23 2002, 12:02:55) 
[GCC 3.0.3] on sunos5 
Type "help", "copyright", "credits" or "license" for more 
information. 
>>> x = 4503599627370496L 
>>> y = 4503599627370496 
>>> h = {x: 'anything', y: 'something else'} 
>>> h[x] 
'anything' 
>>> h[y] 
'something else' 
>>> x == y 
1 
 
All the best, 
 
Mark 
 

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=689659&group_id=5470