Started in #13104, turned into a tracking issue here.

Turning on -n in sphinx-build results in over 1000 warnings about bad references in docs. Trying to break these down with various grep statements, it seems about 200 are from numpy.ma, about 150 from polynomial and about 150 from c:type. That is under half of the WARNINGS.

My workflow is to cd to the doc directory, modify the ALLSPHINXOPTS in the Makefile and add -n`, My workflow is to set an environment variable SPHINXOPTS='-n' then run

(cd ..; pip install .); make clean; make html 2>&1 |tee /tmp/build.txt
less /tmp/build.txt

and look for the most common lines. Unfortunately this takes quite a while.

Anyone who wishes to contribute can issue PRs, preferably in chunks that address one class of failure. #13104 gives an idea of the changes needed.