http://codereview.appspot.com/14105/diff/1/11
File Doc/library/sys.rst (right):

http://codereview.appspot.com/14105/diff/1/11#newcode418
Line 418: A struct sequence that holds information about Python's
I don't think the sequence interface is really important here. There
should be a way to easily define regular struct-like classes (with no
sequence interface). Perhaps structseq could be modified to drop
sequence interface, and new structseqs should turn it off usually.

http://codereview.appspot.com/14105/diff/1/6
File Include/longintrepr.h (right):

http://codereview.appspot.com/14105/diff/1/6#newcode24
Line 24: Furthermore, NSMALLNEGINTS and NSMALLPOSINTS should fit in a
digit. */
Merge the comments into a single on. There is no need to preserve the
evolution of the code in the comment structure.

http://codereview.appspot.com/14105/diff/1/9
File Objects/longobject.c (right):

http://codereview.appspot.com/14105/diff/1/9#newcode2872
Line 2872: /* XXX benchmark this! Is is worth keeping? */
Why not PyLong_FromLongLong if available (no special case if not)?

http://codereview.appspot.com/14105/diff/1/10
File PC/pyconfig.h (right):

http://codereview.appspot.com/14105/diff/1/10#newcode318
Line 318: #define PY_UINT64_T unsigned __int64
I think this should use PY_LONG_LONG, to support MingW32; likewise,
__int32 shouldn't be used, as it is MSC specific

http://codereview.appspot.com/14105/diff/1/2
File Python/marshal.c (right):

http://codereview.appspot.com/14105/diff/1/2#newcode160
Line 160: w_long((long)(Py_SIZE(ob) > 0 ? l : -l), p);
This needs to deal with overflow (sizeof(size_t) > sizeof(long))

http://codereview.appspot.com/14105/diff/1/2#newcode540
Line 540: if (n < -INT_MAX || n > INT_MAX)
I think this is obsolete now; longs can have up to ssize_t_max digits.

http://codereview.appspot.com/14105/diff/1/8
File configure.in (right):

http://codereview.appspot.com/14105/diff/1/8#newcode3132
Line 3132: # determine what size digit to use for Python's longs
I'm skeptical (-0) that we really need to have such a configure option.

http://codereview.appspot.com/14105/diff/1/14
File pyconfig.h.in (left):

http://codereview.appspot.com/14105/diff/1/14#oldcode9
Line 9: #undef AC_APPLE_UNIVERSAL_BUILD
We should find out why this is gone.

http://codereview.appspot.com/14105/diff/1/14#oldcode958
Line 958: /* Enable extensions on AIX 3, Interix.  */
Likewise, this needs to be preserved.

http://codereview.appspot.com/14105/diff/1/14#oldcode1017
Line 1017: /* Define WORDS_BIGENDIAN to 1 if your processor stores words
with the most
This also needs to be preserved.

http://codereview.appspot.com/14105

This was meant to go to issue4258, but I failed to set the subject when
sending this from Rietveld.

Well, it might have helped if I'd used the same title for the Rietveld 
issue as the tracker issue.  I'll get that right next time.

Thank you for the review.  I'll post some proper responses tomorrow 
evening (GMT).

> Well, it might have helped if I'd used the same title for the Rietveld 
> issue as the tracker issue.  I'll get that right next time.

What matters (I think) is that you have [issueXYZ] in the subject.