[issue9778] Make hash values the same width as a pointer (or Py_ssize_t)

[Alexander Belopolsky]

Alexander Belopolsky <belopolsky at users.sourceforge.net> added the comment:

On Mon, Oct 18, 2010 at 11:27 AM, Antoine Pitrou <report at bugs.python.org> wrote:
..
>> The benefit, though is that
>> hash computations can be performed natively on the hash values without
>> casting to an unrelated type.
>
> I don't understand what you mean by "native" and "unrelated". Signed
> integers are not less native than unsigned ones.

Sorry, I could have been clearer indeed.   Consider the following code:

static Py_hash_t
long_hash(PyLongObject *v)
{
    unsigned long x;
...
    x = x * sign;
    if (x == (unsigned long)-1)
        x = (unsigned long)-2;
    return (Py_hash_t)x;
}

Wouldn't it be cleaner if x was the same type as hash?  Note that
unsigned long is now wrong.  What is needed is "unsigned integer type
of the same size as Py_hash_t."  If Py_hash_t has to stay signed, I
think we should at least not rely of sizeof(Py_hash_t) to always
remain the same as sizeof(size_t).

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue9778>
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