[llvm-dev] Migrate utils/ Python 2 scripts to Python 3

[Chris Matthews via llvm-dev]

Personally, every machine I work with only has Python 2.7.

Justin is correct that there is a non-trivial amount of effort to convert the bots. 

Python 3 is wonderful. But, a Python 3 dependency seems like one burden that could be avoided.  We have already made that trade-off in the past, for example by only using standard python packages, so there is less/nothing to pip install when getting started.  Dependencies likes host compiler and cmake totally make sense given they are central to how LLVM is made.  I don’t think the same for the python code.

I’m in favor of 2/3 compatibility until the death clock ends.

> On Jan 30, 2018, at 4:48 AM, 陳韋任 via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Does Python 3 have feature we want to use in LLVM codebase, and no workaround there? If so, please give some examples. I think that makes the discussion more concrete.
> 
> 2018-01-30 4:46 GMT+08:00 Fāng-ruì Sòng via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>>:
> Hi LLVM-Devs,
> 
> I noticed that many Python scripts under utils/ have a shebang of
> `#!/usr/bin/python` (which is a symlink to python2.7 on many platforms) and some of them use Python 2 syntax that is not compatible with Python 3 (e.g. print statements; str/bytes)
> 
> I created a revision to migrate utils/update_{llc_,}_test_checks.py from Python 2 to Python 3 https://reviews.llvm.org/D42450 <https://reviews.llvm.org/D42450> , the arguments against making it Python 3 is:
> 
> * There are many Mac OS X users and Mac OS X 10.8 comes with Python 2.7 pre-installed [0] but not Python 3.
> * Forcing scripts to use Python 3 (by doing so we can avoid some compatibility trouble) may not be a good idea.
> 
> Python 2.7 was published in 2010 and planned as the last of the 2.x releases. It will not be maintained past 2020 and there is also a retirement page https://pythonclock.org/ <https://pythonclock.org/> .
> 
> The second argument would not need to be addressed if the first one did not lay too much burden on developers. After all, we have to install `cmake, ninja/GNU Make / libedit(for lldb)` to build LLVM. These packages are not installed by default on many platforms.
> 
> Thoughts on deprecating Python 2 for utils/ scripts (different from libclang or lldb scripts) which are not user-facing?
> 
> [0]: https://docs.python.org/3/using/mac.html#getting-and-installing-macpython <https://docs.python.org/3/using/mac.html#getting-and-installing-macpython>
> 
> 
> Thanks,
> Fangrui
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> 
> 
> 
> -- 
> Wei-Ren Chen (陳韋任)
> Homepage: https://people.cs.nctu.edu.tw/~chenwj <https://people.cs.nctu.edu.tw/~chenwj>_______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180130/cc7791bf/attachment.html>