Re: Sphinx pre v3 -- removing support

[Jonathan Corbet <corbet@lwn.net>]

Adam Turner <aaturnerpython@outlook.com> writes:

>> We've been meaning to raise the minimum version for a bit.  Going to v3
>> might be a bit of a stretch, though.  I still do most of my test builds
>> with 2.4.3 just because Sphinx got so....much........slower with 3.0.
>> I've not yet had a chance to try out 5.0 to see if that helps things,
>> that's on my list to do soon.
>
> Sphinx 5.0 should be faster, I changed the logic to cache and reuse
> the core publisher objects [1]_. I haven't compared to 2.4.3 though.

So ... here are a few "make htmldocs" builds that I ran

  VERSION  BUILD TIME
  2.4.3     5:24
  4.1.2    10:51
  4.5.0    10:57
  5.0.1    11:17

So 5.0 has actually regressed from 4.5 in terms of speed, and takes more
than twice the time that 2.4.3 takes.  These slow builds are really
painful when I'm working through the docs patch queue and have to build
things frequently; they are also a disincentive for other developers to
build the docs and make sure they haven't broken anything.

(Interestingly, total CPU time is ~16:45 for 2.4.3, and ~21:45 for the
later versions.  So latter-day Sphinx does use more CPU, but it also
seems to have lost some parallelism.)

I hope you understand why that makes me reluctant to move the minimum
version up to 3.0.  But, looking further at this conversation, I don't
think we need to at this point.  You said:

> I'm referring to removing support for the "c_allow_pre_v3", 
> "c_warn_on_allowed_pre_v3", configuration options [1]_, and the 
> associated support for still parsing the pre v3 syntax in the C 
> domain [2]_. This means that pre v3 syntax in reStructuredText files
> would not work with Sphinx 6 onwards.

Having looked through the all-too-numerous warnings emitted by our docs
build, I don't see any that look like they would be tied to pre-v3
C-domain syntax.  I *believe* that you could remove that support and it
wouldn't bother us, unless there's something I'm missing?

I truly appreciate your contacting us about this - thanks!

jon