Re: [PATCH for 5.1] docs: fix trace docs build with sphinx 3.1.1

[John Snow <jsnow@redhat.com>]

On 7/27/20 4:14 PM, Peter Maydell wrote:
> On Mon, 27 Jul 2020 at 20:52, John Snow <jsnow@redhat.com> wrote:
>> ... Should we say goodbye to Sphinx 1.7.x, or is there a workaround that
>> keeps support from 1.6.1 through to 3.1.1?
> 
> I think we need to keep 1.7.x because it's the Sphinx shipped
> by some LTS distros we support, don't we?
> 

Only if you feel it's important that doc building works using packages 
from the system repo. `pip3 install --user sphinx` works on all of these 
distros, too.

We already somewhat break our promise where Sphinx is concerned for the 
oldest distros on our support list.

> I do feel we probably need to defend our Sphinx-version-support
> more actively by having oldest-supported and bleeding-edge
> both tested in the CI setup...
> 

We could either:

A) Start using a "build venv" that uses specific sets of python packages 
for the build process to pin everyone's build at version 1.6.1

B) Add some sort of pytest/tox/whatever to add a test that does a sphinx 
doc build across multiple different versions, 1.6.1, 1.7.x, 2.0.x, etc.

(I don't think you liked the idea of a Python environment in QEMU taking 
responsibility of Sphinx, though ...)