Sphinx build failing

[sylee957]

The recent build had failed after sphinx had been updated to 2.1.0,
https://travis-ci.org/sympy/sympy/builds/540395440
I've confirmed that the fail is due to the update today.

[moorepants]

Maybe Sphinx should be pinned to a specific version on CI and only updated manually.

[oscarbenjamin]

So the duplicate references are in:

1. doc/src/modules/holonomic/operations.rst
2. doc/src/modules/holonomic/convert.rst

They both have references to

.. module:: sympy.holonomic.holonomic

I've tried deleting each and either way I get an error e.g.:

don't know which module to import for autodocumenting 'HolonomicFunction.integrate' (try placing a "module" or "currentmodule" directive in the document, or giving an explicit module name)
make: *** [html] Error 2

[sylee957]

I think that ..module:: directive was used to manage the context, allowing some usage like HolonomicFunction.integrate instead of sympy.holonomic.holonomic.HolonomicFunction.integrate, so without the directive, it should be rewritten as latter.

However, it still fails with

duplicate object description of sympy.simplify.cse_main, other instance in modules/rewriting, use :noindex: for one of them
Makefile:49: recipe for target 'html' failed

even after the changes,
and it seems like module directive is used in more places than holonomic.

I'm still not sure if sympy had been using deprecated features, or sphinx had introduced some regressions.
If no good solution comes out in days, I'd support pinning down.

[sidhantnagpal]

+1 to pinning (at least until a resolution). A version prior to 2.0 could be used, given that formatting has also been affected with the new version, ref: #16585.

[jksuom]

The original error message suggests using the :noindex: directive. Could that be possible?