[LLVMdev] Minimum Python Version

Marc J. Driftmeyer mjd at reanimality.com
Sun Dec 2 23:18:42 PST 2012

One of the most conservative distributions is Debian.

The python_defaults package has moved to 2.7.3 in Sid and 2.7.3~rc2-1 in 
Wheezy (Debian 7.0 now on its 4th beta and soon to be release candidate 

I personally run Sid/Unstable in order to get general release builds of 
LLVM/Clang > 2.9, never mind 3.2.

It seems reasonable to target 2.7.3 as the oldest python release.

- Marc J. Driftmeyer

On 12/01/2012 12:57 PM, Gregory Szorc wrote:
> I'd like to continue the discussion about minimum Python versions from 
> the "Use multiprocessing instead of threading" thread in its own 
> thread because I feel it warrants additional discussion.
> In that thread, we were discussing maintaining support for Python 2.4 
> and 2.5. The latest response is:
> On Fri, Nov 30, 2012 at 1:40 PM, Daniel Dunbar <daniel at zuster.org 
> <mailto:daniel at zuster.org>> wrote:
>     My official opinion on Python version support is to maintain old
>     compatibility, unless it is causing large problems with the code.
> I would like to offer a counter opinion.
> I believe LLVM should drop support for Python 2.4 and 2.5 for 2 main 
> reasons:
> 1) Python 2.4 and 2.5 are end-of-lifed
> 2) Python 3 is coming
> IMO, #1 should be reason enough. Let me explain #2.
> All the Python in the tree will need to eventually support Python 3. 
> "Modern" Linux distributions like Ubuntu are already shipping Python 3 
> as /usr/bin/python (while still offering 2.7 because the overwhelming 
> amount of Python in the wild doesn't yet work on Python 3).
> The road to Python 3 for LLVM will likely come via Python code that 
> works under both 2.x and 3.x (I'm assuming nobody wants a flag day). 
> From my personal experience, I can unequivocally say that writing 
> Python that works on both major versions is much easier the closer the 
> Python 2 release is to 3. In other words, It's much easier to dually 
> support Python 2.7 and 3.x than it is 2.5 and 3.x. I feel the level of 
> pain is pretty bad until you get to Python 2.6. Even then, there are 
> dozens of small bugs in Python 2.6 and even earlier releases of Python 
> 2.7 until 2.7.3 that make dual support difficult (especially in the 
> area of Unicode handling).
> For these reasons, I urge LLVM to drop support for Python older than 
> 2.6. I would encourage requiring 2.7 (preferably the latest available 
> release - 2.7.3 at this time) at the earliest convenience, but I'm not 
> explicitly asking for it. While continued support for older Pythons is 
> a noble goal and may continue to support people clinging to ancient 
> Python releases, this will only make the path forward more difficult, 
> as it puts an additional burden on those maintaining Python in the tree.
> FWIW, I've been pushing this same argument at Mozilla for the Firefox 
> tree [1], where so far it has been winning. We dropped Python 2.5 
> about 6 weeks ago and IIRC the only issue was we forgot to update one 
> set of builders before we made the change. We have loosely agreed that 
> we want to move everything to Python 2.7 (then 2.7/3.x and then 
> eventually 3.x) and will be discussing this change in the days ahead. 
> While I'm sure LLVM supports some more esoteric platforms than 
> Firefox, I believe the data point is still relevant and LLVM could 
> make a similar transition without a major headache.
> [1] 
> https://groups.google.com/d/topic/mozilla.dev.platform/djN02O03APc/discussion
> Gregory
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Marc J. Driftmeyer
Email :: mjd at reanimality.com <mailto:mjd at reanimality.com>
Web :: http://www.reanimality.com
Cell :: (509) 435-5212
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