The attached file lists many of the warnings, but note there may be more as tkinter didn't build and is subject to #23449.

Using Microsoft Visual Studio Express 2013 for Windows Desktop.

These are warnings about implicit downcasting in a 64-bit build. They're not fatal to the build or execution (as far as we know), and as nice as it would be to fix them all, "good" fixes may introduce behaviour changes (for example, new overflow errors).

As an aside, building with VS 2015 also shows a lot of warnings for variable shadowing, which should also be fixed but is not likely unless someone gets really annoyed by them. What's the usual policy on issues like this?

Changes to nosy list as advised by Terry Reedy on c.l.py

Here is a patch which fixes many warnings reported by MS compiler on 64-bit platform [1]. Some of these warnings indicated real bugs.

[1] http://buildbot.python.org/all/builders/AMD64%20Windows8%203.x/builds/411/steps/compile/logs/warnings%20(396)

The 64-bit support of Windows is still incomplete :-/ We tried to fix most of them, but there are still remaining issues.

The main issue is #9566. I opened for example the issue #18295: "Possible integer overflow in PyCode_New()".

signal_cast_socket_t.patch: Fix warning in signal.set_wakeup_fd(). I introduced recently the warning when I added support for sockets in this function on Windows.

signal_cast_socket_t.patch LGTM.

Wow, I didn't expect that so quickly :)

I'll check these out as soon as I can, but they look okay from a quick glance on my phone.

New changeset 9e10c4255277 by Victor Stinner in branch 'default':
Issue #23450: Fix signal.set_wakeup_fd() on Windows
https://hg.python.org/cpython/rev/9e10c4255277

Please ignore changes to Objects/codeobject.c, Objects/funcobject.c and Python/ceval.c. The patch in issue18295 is more advanced.

int_overflows.patch looks good to me.

I really appreciate that these patches have been done properly too - I've seen far too much code where people just throw in casts to silence the warnings. This is why I like working on Python :)

New changeset a84ae2ccd220 by Serhiy Storchaka in branch 'default':
Issue #23450: Fixed possible integer overflows.
https://hg.python.org/cpython/rev/a84ae2ccd220

New changeset 1eee26b74e4b by Serhiy Storchaka in branch 'default':
Issue #23450: Silenced compiler warnings and added asserts in peephole optimizer.
https://hg.python.org/cpython/rev/1eee26b74e4b

New changeset f47d683b6c9e by Serhiy Storchaka in branch 'default':
Fixed sizeof tests for ElementTree (issue #23450).
https://hg.python.org/cpython/rev/f47d683b6c9e