autodoc: single-string __slots__ is not handled correctly

[mgeier]

When documenting a Python module like this (using the sphinx.ext.autodoc extension):

.. automodule:: mymodule
   :members:
   :undoc-members:

... and mymodule.py has a class with a __slots__ attribute that consists of a single string like this:

class MyClassWithSlots:

    __slots__ = 'abc'

... the generated class documentation contains each of the characters in addition to the whole string:

Please note that the Python docs explicitly allow a single string (and not only iterables):

This class variable can be assigned a string, iterable, or sequence of strings with variable names used by instances.

When using a tuple or a list of string, everything is fine:

Expected behavior

Environment info

• Sphinx version: any version, including 3.x and master branch