formulae*: deprecate formulae which depend on Python 2

[danielnachun]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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[danielnachun]

In support #93940, these 6 formulae depend on Python 2 and their upstream development appears stalled. I have also set maximum_macos to big_sur to prevent these from being built or installed on Monterey, which will no longer have Python 2 when the 12.3 update is released.

[Bo98]

I have also set maximum_macos to big_sur to prevent these from being built or installed on Monterey

Just to check: do all these require Python 2 at runtime?

[Bo98]

Any reason for this date? Probably better to just make it today's date so we know when we actually deprecated it.

[danielnachun]

The reason I chose was because it was the day after the release of Python 2.7.18. I happened to see this used for libgraphqlparser, but it seems that this was merged even though there was a desire to use the present date instead. So I will just use today's date instead (for me in the US).

[danielnachun]

I have also set maximum_macos to big_sur to prevent these from being built or installed on Monterey

Just to check: do all these require Python 2 at runtime?

Good question. appscale-tools, git-remote-hg and rfcmarkup appear to be pure Python programs, so I assume they do need Python 2 at runtime. blastem seems to have some support scripts written in Python, but the core program is written in C. libming and rethinkdb are written in C/C++ and have Python 2 bindings.

Maybe we should only set maximum_macos: :big_sur for the 3 formulae that require Python 2 at run time?

[Bo98]

Maybe we should only set maximum_macos: :big_sur for the 3 formulae that require Python 2 at run time?

Yes. If it's Python 2 bindings, then they should just be removed. As for support scripts, depends how critical they are.

If it's mandatory to build (i.e. Python 2 in invoked in build scripts) then there's also maximum_macos: [:big_sur, :build] (or something like that).

[nandahkrishna]

I just contacted the maintainer of blastem, and it seems like only one Python file (img2tiles.py) is actually run during the build while the other Python scripts are used for testing. They've updated img2tiles.py to be Python 3-compatible, and I've asked if it would be possible to make a release soon.

[danielnachun]

I just contacted the maintainer of blastem, and it seems like only one Python file (img2tiles.py) is actually run during the build while the other Python scripts are used for testing. They've updated img2tiles.py to be Python 3-compatible, and I've asked if it would be possible to make a release soon.

Thanks for looking into that. If they are interested in making a new release that is Python 3 compatible, I'll drop blastem from this PR and we can instead update it in a new PR.

[danielnachun]

Maybe we should only set maximum_macos: :big_sur for the 3 formulae that require Python 2 at run time?

Yes. If it's Python 2 bindings, then they should just be removed. As for support scripts, depends how critical they are.

If it's mandatory to build (i.e. Python 2 in invoked in build scripts) then there's also maximum_macos: [:big_sur, :build] (or something like that).

It does appear that Python bindings can be disabled for libming. I'll test this under Linux where it will obviously fail if it still needs Python 2. If it can be build without the Python bindings, I'll drop it from here and open a PR to disable the bindings instead.

I think I was wrong about how rethinkdb depends on Python 2. It is indeed build-only, and it is because it builds an ancient version of v8 that require Python 2 to compile. There is an open issue for replacing v8 with QuickJS (rethinkdb/rethinkdb#6960) but the PR to implement that hasn't seen activity for 7 months rethinkdb/rethinkdb#6978. Perhaps it's worth posting in the upstream issue that it will no longer be possible to build rethinkdb on macOS 12.3.

[danielnachun]

Two small updates for this:

1. There is actually an upstream commit for blastem that converts that img2tiles.py script to use Python 3: https://www.retrodev.com/repos/blastem/raw-rev/dbbf0100f249. Assuming we are able to apply that to the formula, that would allow us to immediately switch blastem to Python 3.

2. I found this issue in in the rethinkdb GitHub that pretty clearly indicates the project is now unmaintained because the parent company developing it no longer exists: Rethinkdb status rethinkdb/rethinkdb#6981. It sounds like MongoDB and RavenDB can replace the functionality of RethinkDB, though neither have licenses compatible with packaging for Homebrew. I have no hesitation now in deprecating this formula, though because it only has a build dependency on Python 2, we don't need to set maximum_macos for it, and the existing bottles may continue to work on newer macOS versions for some time.

[danielnachun]

I've updated this to drop libming and blastem from the PR because they are being updated instead of deprecated. I changed the deprecation date to today and because rethinkdb only has a build a dependency on Python 2, I changed it to depends_on maximum_macos: [:big_sur, :build]. The other 3 formulae need Python 2 at runtime and will not be usable at all in Monterey after the 12.3 update.

[danielnachun]

I'm going to close this in favor of doing these deprecations individually, as I think it can get too complicated when handling more than one formula.