An upstream comment says common.py:lazy_property is the problem item,
and excluding that from the documentation does make Sphinx succeed (I
haven't tested a whole build):
--- snakemake-5.10.0.orig/docs/conf.py
+++ snakemake-5.10.0/docs/conf.py
@@ -107,6 +107,8 @@ pygments_style = 'sphinx'
# If true, keep warnings as "system message" paragraphs in the built
documents.
#keep_warnings = False
+# skip internal class that Sphinx 2 can't process (#296)
+autodoc_default_options = {'exclude-members': 'lazy_property'}
# -- Options for HTML output
----------------------------------------------
This is obviously not an ideal fix, but it's an internal class with
little documentation to begin with:
https://snakemake.readthedocs.io/en/stable/api_reference/internal/snakemake.html#snakemake.common.lazy_property
