AttributeError: 'getset_descriptor' object has no attribute 'expandtabs'

[laloch]

I'm getting the following backtrace while trying to build http://github.com/xonsh/xonsh documentation:

# Sphinx version: 3.0.0
# Python version: 3.8.2 (CPython)
# Docutils version: 0.16 release
# Jinja2 version: 2.11.1
# Last messages:
#   reading sources... [ 20%] api/execer
#   reading sources... [ 21%] api/foreign_shells
#   reading sources... [ 22%] api/history/base
#   reading sources... [ 22%] api/history/index
#   reading sources... [ 23%] api/history/json
#   reading sources... [ 24%] api/history/main
#   reading sources... [ 25%] api/history/sqlite
#   reading sources... [ 25%] api/imphooks
#   reading sources... [ 26%] api/index
#   reading sources... [ 27%] api/inspectors
# Loaded extensions:
#   sphinx.ext.mathjax (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/mathjax.py
#   sphinxcontrib.applehelp (1.0.2) from /usr/local/lib/python3.8/site-packages/sphinxcontrib/applehelp/__init__.py
#   sphinxcontrib.devhelp (1.0.2) from /usr/local/lib/python3.8/site-packages/sphinxcontrib/devhelp/__init__.py
#   sphinxcontrib.htmlhelp (1.0.3) from /usr/local/lib/python3.8/site-packages/sphinxcontrib/htmlhelp/__init__.py
#   sphinxcontrib.serializinghtml (1.1.4) from /usr/local/lib/python3.8/site-packages/sphinxcontrib/serializinghtml/__init__.py
#   sphinxcontrib.qthelp (1.0.3) from /usr/local/lib/python3.8/site-packages/sphinxcontrib/qthelp/__init__.py
#   alabaster (0.7.12) from /usr/local/lib/python3.8/site-packages/alabaster/__init__.py
#   sphinx.ext.autodoc.type_comment (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/autodoc/type_comment.py
#   sphinx.ext.autodoc (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/autodoc/__init__.py
#   sphinx.ext.doctest (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/doctest.py
#   sphinx.ext.imgmath (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/imgmath.py
#   sphinx.ext.graphviz (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/graphviz.py
#   sphinx.ext.inheritance_diagram (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/inheritance_diagram.py
#   sphinx.ext.viewcode (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/viewcode.py
#   sphinx.ext.autosummary (3.0.0) from /usr/local/lib/python3.8/site-packages/sphinx/ext/autosummary/__init__.py
#   numpydoc (0.9.2) from /usr/local/lib/python3.8/site-packages/numpydoc/__init__.py
#   cmdhelp (unknown version) from /xonsh/docs/cmdhelp.py
#   runthis.sphinxext (unknown version) from /usr/local/lib/python3.8/site-packages/runthis/sphinxext.py
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/sphinx/cmd/build.py", line 280, in build_main
    app.build(args.force_all, filenames)
  File "/usr/local/lib/python3.8/site-packages/sphinx/application.py", line 348, in build
    self.builder.build_update()
  File "/usr/local/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 297, in build_update
    self.build(to_build,
  File "/usr/local/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 311, in build
    updated_docnames = set(self.read())
  File "/usr/local/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 418, in read
    self._read_serial(docnames)
  File "/usr/local/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 439, in _read_serial
    self.read_doc(docname)
  File "/usr/local/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 479, in read_doc
    doctree = read_doc(self.app, self.env, self.env.doc2path(docname))
  File "/usr/local/lib/python3.8/site-packages/sphinx/io.py", line 221, in read_doc
    pub.publish()
  File "/usr/local/lib/python3.8/site-packages/docutils/core.py", line 217, in publish
    self.document = self.reader.read(self.source, self.parser,
  File "/usr/local/lib/python3.8/site-packages/sphinx/io.py", line 126, in read
    self.parse()
  File "/usr/local/lib/python3.8/site-packages/docutils/readers/__init__.py", line 77, in parse
    self.parser.parse(self.input, document)
  File "/usr/local/lib/python3.8/site-packages/sphinx/parsers.py", line 102, in parse
    self.statemachine.run(inputlines, document, inliner=self.inliner)
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 170, in run
    results = StateMachineWS.run(self, input_lines, input_offset,
  File "/usr/local/lib/python3.8/site-packages/docutils/statemachine.py", line 241, in run
    context, next_state, result = self.check_line(
  File "/usr/local/lib/python3.8/site-packages/docutils/statemachine.py", line 459, in check_line
    return method(match, context, next_state)
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 3005, in text
    self.section(title.lstrip(), source, style, lineno + 1, messages)
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 327, in section
    self.new_subsection(title, lineno, messages)
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 393, in new_subsection
    newabsoffset = self.nested_parse(
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 281, in nested_parse
    state_machine.run(block, input_offset, memo=self.memo,
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 196, in run
    results = StateMachineWS.run(self, input_lines, input_offset)
  File "/usr/local/lib/python3.8/site-packages/docutils/statemachine.py", line 241, in run
    context, next_state, result = self.check_line(
  File "/usr/local/lib/python3.8/site-packages/docutils/statemachine.py", line 459, in check_line
    return method(match, context, next_state)
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 2342, in explicit_markup
    nodelist, blank_finish = self.explicit_construct(match)
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 2354, in explicit_construct
    return method(self, expmatch)
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 2096, in directive
    return self.run_directive(
  File "/usr/local/lib/python3.8/site-packages/docutils/parsers/rst/states.py", line 2146, in run_directive
    result = directive_instance.run()
  File "/usr/local/lib/python3.8/site-packages/sphinx/ext/autodoc/directive.py", line 146, in run
    documenter.generate(more_content=self.content)
  File "/usr/local/lib/python3.8/site-packages/sphinx/ext/autodoc/__init__.py", line 769, in generate
    self.document_members(all_members)
  File "/usr/local/lib/python3.8/site-packages/sphinx/ext/autodoc/__init__.py", line 659, in document_members
    for (mname, member, isattr) in self.filter_members(members, want_all):
  File "/usr/local/lib/python3.8/site-packages/sphinx/ext/autodoc/__init__.py", line 570, in filter_members
    metadata = extract_metadata(doc)
  File "/usr/local/lib/python3.8/site-packages/sphinx/util/docstrings.py", line 29, in extract_metadata
    for line in prepare_docstring(s):
  File "/usr/local/lib/python3.8/site-packages/sphinx/util/docstrings.py", line 54, in prepare_docstring
    lines = s.expandtabs(tabsize).splitlines()
AttributeError: 'getset_descriptor' object has no attribute 'expandtabs'

Steps to reproduce:

$ git clone https://github.com/xonsh/xonsh.git
$ cd xonsh/docs
$ make html

[tk0miya]

Wow, it seems one of the object in your library returns non-string object as a __doc__ member. I feel this is broken, but okay, I'll fix this later.

<attribute '__doc__' of 'builtin_function_or_method' objects>

[laloch]

Oops, you're absolutely right:

>>> type(xonsh.inspectors._builtin_func_type.__doc__)
getset_descriptor
>>> type(xonsh.inspectors._builtin_meth_type.__doc__)
getset_descriptor