Smart quotes get applied to highlighted inline code expressions

[JustinTArthur]

Describe the bug

Given some RST that includes text with a :code: role and a language option, sphinx will produce HTML with highlighting for that text's code language. However, if that highlighting introduces more than one sub-level of output nodes, we fail to detect that the text is part of a no-smartquotes zone and mangle text that is intended to be presented literally.

How to Reproduce

The following RST:

.. role:: python(code)
   :language: python

By setting :python:`foo = 'bar'`, we have assigned a variable.

produces HTML like

By setting
<code class="code python docutils literal notranslate">
  <span class="name"><span class="pre">foo</span></span>
  <span class="operator"><span class="pre">=</span></span>
  <span class="literal string single"><span class="pre">‘bar’</span></span>
</code>, we have assigned a variable.

Notice the right/left single quotes added by Sphinx in ‘bar’. Because the text node is two ancestors away from the document's code node instead of one, it isn't detected as protected from smartquotes.

Expected behavior

Straight single and double-quote characters in inline code expressions should be left alone, regardless of whether or not a specific language option is applied.

docutils' built-in smartquotes transformer correctly avoids the highlighted quotation marks.

Your project

Small Sphinx 4 project sample attached.

Screenshots

No response

OS

macOS

Python version

3.9

Sphinx version

4.1.2

Sphinx extensions

No response

Extra tools

No response

Additional context

No response

[JustinTArthur]

smartquotes_code_role_example.zip as requested by the GitHub ticket template.