Previously, ``nested_parse_with_titles`` always passed ``0`` as the input
offset when invoking ``nested_parse``. When parsing the content of a
directive, as is a common use case for ``nested_parse_with_titles``,
this leads to incorrect source file/line number information, as it
does not take into account the directive's ``content_offset``, which is
always non-zero.
This issue affects *all* object descriptions due to GH-10887. It also
affects the ``sphinx.ext.ifconfig`` extension.
The ``py:module`` and ``js:module`` directives employed a workaround for
this issue, by wrapping the calls to ``nested_parse_with_title`` with
``switch_source_input``. That worked, but was more complicated (and
likely less efficient) than necessary.
This commit adds an optional ``content_offset`` parameter to
``nested_parse_with_titles``, and fixes callers to pass the appropriate
content offset when needed.
This commit eliminates the now-unnecessary calls to
``switch_source_input`` and instead specifies the correct ``content_offset``.
