llvm dev - Dec 2019 - Python 2 compatibility for utility scripts

On Tue, Dec 17, 2019 at 12:55 PM Nico Weber <thakis at chromium.org>
wrote:
> On Tue, Dec 17, 2019 at 12:41 PM James Y Knight <jyknight at
google.com>
> wrote:
>
>> It sounds like you ran into a bug in the test infrastructure's code
to
>> determine if python3 is supported. Fixing that might be harder, but it
only
>> needs to be fixed once no matter how much more python3 development
there
>> will be.
>>
>
> No, it was in some local.lit.cfg.
>
I see that now. Sure, in that case I suggest to fix whatever the issue is *and
move* it to common code, so that the "python3" feature is correctly
detected and available to any test.

Right now, most of our scripts were originally written for python 2,
so
>> certainly it's easy for them to support python 2. But, it was a lot
of work
>> by various people to port them all to additionally work in python 3.
And,
>> in the future (or maybe even now), people will be generally be writing
>> python3 scripts by default rather than python2. Certainly they ought
to.
>>
>> I just don't think it's worthwhile to require all new such
scripts to
>> continue to be written bilingually, unless doing that extra work helps
to
>> serve users.
>>
>> I'm not at all worried about a hypothetical case where we want to
ship a
>> script that was written for python3 only. Firstly, because that usually
>> doesn't happen. But if it does, we can port it then, or else we
might just
>> decide it's fine for it to be python3 only.
>>
>
> You don't see any advantage to having a consistent language level
across
> the project? (See also the flang vs c++17 discussion.)
>
In this particular situatoin, correct. For these auxilliary scripts which
are not released or used to build/test released components, I see no
advantage to requiring these to support python2, anymore.
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On Tue, Dec 17, 2019 at 1:15 PM James Y Knight <jyknight at google.com>
wrote:
>
>
> On Tue, Dec 17, 2019 at 12:55 PM Nico Weber <thakis at chromium.org>
wrote:
>
>> On Tue, Dec 17, 2019 at 12:41 PM James Y Knight <jyknight at
google.com>
>> wrote:
>>
>>> It sounds like you ran into a bug in the test infrastructure's
code to
>>> determine if python3 is supported. Fixing that might be harder, but
it only
>>> needs to be fixed once no matter how much more python3 development
there
>>> will be.
>>>
>>
>> No, it was in some local.lit.cfg.
>>
>
> I see that now. Sure, in that case I suggest to fix whatever the issue is
*and
> move* it to common code, so that the "python3" feature is
correctly
> detected and available to any test.
>
> Right now, most of our scripts were originally written for python 2, so
>>> certainly it's easy for them to support python 2. But, it was a
lot of work
>>> by various people to port them all to additionally work in python
3. And,
>>> in the future (or maybe even now), people will be generally be
writing
>>> python3 scripts by default rather than python2. Certainly they
ought to.
>>>
>>> I just don't think it's worthwhile to require all new such
scripts to
>>> continue to be written bilingually, unless doing that extra work
helps to
>>> serve users.
>>>
>>> I'm not at all worried about a hypothetical case where we want
to ship a
>>> script that was written for python3 only. Firstly, because that
usually
>>> doesn't happen. But if it does, we can port it then, or else we
might just
>>> decide it's fine for it to be python3 only.
>>>
>>
>> You don't see any advantage to having a consistent language level
across
>> the project? (See also the flang vs c++17 discussion.)
>>
>
> In this particular situatoin, correct. For these auxilliary scripts which
> are not released or used to build/test released components, I see no
> advantage to requiring these to support python2, anymore.
>
Well, I disagree :)

I'm curious what others think.
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On 12/17/19 10:33 AM, Nico Weber via llvm-dev wrote:
> On Tue, Dec 17, 2019 at 1:15 PM James Y Knight <jyknight at google.com 
> <mailto:jyknight at google.com>> wrote:
>
>
>
>     On Tue, Dec 17, 2019 at 12:55 PM Nico Weber <thakis at chromium.org
>     <mailto:thakis at chromium.org>> wrote:
>
>         On Tue, Dec 17, 2019 at 12:41 PM James Y Knight
>         <jyknight at google.com <mailto:jyknight at
google.com>> wrote:
>
>             It sounds like you ran into a bug in the test
>             infrastructure's code to determine if python3 is
>             supported. Fixing that might be harder, but it only needs
>             to be fixed once no matter how much more python3
>             development there will be.
>
>
>         No, it was in some local.lit.cfg.
>
>
>     I see that now. Sure, in that case I suggest to fix whatever the
>     issue is /and move/ it to common code, so that the "python3"
>     feature is correctly detected and available to any test.
>
>             Right now, most of our scripts were originally written for
>             python 2, so certainly it's easy for them to support
>             python 2. But, it was a lot of work by various people to
>             port them all to additionally work in python 3. And, in
>             the future (or maybe even now), people will be generally
>             be writing python3 scripts by default rather than python2.
>             Certainly they ought to.
>
>             I just don't think it's worthwhile to require all new
such
>             scripts to continue to be written bilingually, unless
>             doing that extra work helps to serve users.
>
>             I'm not at all worried about a hypothetical case where we
>             want to ship a script that was written for python3 only.
>             Firstly, because that usually doesn't happen. But if it
>             does, we can port it then, or else we might just decide
>             it's fine for it to be python3 only.
>
>
>         You don't see any advantage to having a consistent language
>         level across the project? (See also the flang vs c++17
>         discussion.)
>
>
>     In this particular situatoin, correct. For these auxilliary
>     scripts which are not released or used to build/test released
>     components, I see no advantage to requiring these to support
>     python2, anymore.
>
>
> Well, I disagree :)
>
> I'm curious what others think.
Don't really care, but I have a mild preference for accepting patches to 
keep python2 working.  I wouldn't *require* scripts to work with 
python2, but I see no reason not to land patches if someone wants to put 
in the work.

Philip

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