Fix python3 build on Cygwin

[embray]

Since #22354, Python 3 is now installed unconditionally as a standard package. That's fine, but the last Python 3 version known to work on Cygwin is Python 3.4 (though I have been working with Python upstream to fix that).

In the meantime, here is a patch set needed to get the Python 3 currently in Sage (3.5.1) to at least build, and nominally work.

Component: porting: Cygwin

Author: Erik Bray

Branch/Commit: 5031e42

Reviewer: Travis Scrimshaw, Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/22666

[sagetrac-gouezel]

comment:2

I can confirm that Python 3 builds for me with the patch (and does not without).

[embray]

comment:3

There may still be runtime issues that impact Sage, but I will address those as they come. This at least addresses building without error.

[jdemeyer]

comment:4

What's the upstream status of these patches? I always like when patches have some kind of pointer to an upstream ticket or commit or whatever...

For this reason, I consider the renaming ncurses-issue_14438.patch -> 2.6.5-ncurses-abi6.patch a regression.

[embray]

comment:5

It's just for consistency's sake with the rest of my patch set, who cares what the file is called? I can put in a reference to the issue it addresses.

[jdemeyer]

comment:6

Replying to @embray:

I can put in a reference to the issue it addresses.

Please do (to be clear: renaming the file is fine in that case).

[embray]

comment:7

Yeah, no a problem. I'm pretty sure all of these patches are upstream already, but there might be one or two that aren't for various reasons. Need to double-check.

[tscrim]

comment:8

Did you double-check the patch status Erik? I'm ready to set a positive review unless Jeoren has any other comments (Python3 builds for me with this on Cygwin64).

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

Upstream: None of the above - read trac for reasoning.

[tscrim]

Changed upstream from None of the above - read trac for reasoning. to none

[embray]

comment:11

No, I'll work on that now...

[sagetrac-git]

Changed commit from 133ae6a to 1618c0f

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

a55e734	This is fixed, for now, in sage by https://github.com/sagemath/sage-prod/issues/21399 so we can live without this patch.
90e46fd	This patch has been part of the Cygwin port of Python since Python 2.6, but it has not been needed in Sage.
cd51023	This patch seems to have been part of Cygwin's Python for a long time, but I'm not actually sure what case it's for and can't find anything referencing it.
eb02004	This patch was needed for the tkinter module to build. But we don't guarantee
46df7dc	Rewrote this patch to the actual fix to the issue that was accepted upstream
f7f4535	This patch has been part of Cygwin's Python for a long time, but I don't think it's still needed.
1618c0f	Adds descriptions of more of the new patches

[embray]

comment:13

I removed a handful of patches that didn't actually seem to be needed, and added better descriptions for the rest. With this, Python 3 still builds, and at least nominally works. I should stress that that is the only goal of this ticket. Any other patches needed to Python 3 specifically for Sage features to work (if there are any at all) should be held off until those specific issues come up.

[tscrim]

comment:14

Jeroen, do you have any more comments? Otherwise, I will set a positive review.

[jdemeyer]

comment:15

[comment:6]

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

5031e42

Added a brief description of the ncurses patch with link to the original issue.

[sagetrac-git]

Changed commit from 1618c0f to 5031e42

[embray]

comment:18

Feel free to disagree, but this addresses Jeroen's only comment.

[embray]

Changed reviewer from Travis Scrimshaw to Travis Scrimshaw, Jeroen Demeyer

[jdemeyer]

comment:20

Thanks!

[vbraun]

Changed branch from u/embray/cygwin/python3-build to 5031e42