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

Wed Jan 31 10:48:01 PST 2018

> On Jan 31, 2018, at 10:04 AM, Fāng-ruì Sòng via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Thanks for the information. Then how about standalone scripts (many
> one-file) like utils/update_check_tests.py that are unrelated to lit
> or other important infrastructure? Can they be changed from
> `#!/usr/bin/python2.7` to `#!/usr/bin/python3` shebang?
> 

No. Every machine running macOS has /usr/bin/python and /usr/bin/python2.7 and because of system integrity protection it isn't even possible to install a python3 binary into /usr/bin (You can install it to /usr/local/bin though).

-- adrian

> On Tue, Jan 30, 2018 at 11:20 AM, Chris Matthews
> <chris.matthews at apple.com> wrote:
>> 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>:
>>> 
>>> 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 , 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/ .
>>> 
>>> 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
>>> 
>>> 
>>> Thanks,
>>> Fangrui
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>> 
>> 
>> 
>> 
>> --
>> Wei-Ren Chen (陳韋任)
>> Homepage: 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
>> 
>> 
> 
> 
> 
> -- 
> 宋方睿
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