Thread (10 messages) 10 messages, 2 authors, 2021-06-08

Re: [PATCH 00/34] docs: avoid using ReST :doc:`foo` tag

From: Nícolas F. R. A. Prado <hidden>
Date: 2021-06-08 00:35:58
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Hi Mauro,

On Mon, Jun 07, 2021 at 09:34:22AM +0200, Mauro Carvalho Chehab wrote:
Em Sun, 6 Jun 2021 19:52:25 -0300
Nícolas F. R. A. Prado [off-list ref] escreveu:
quoted
On Sat, Jun 05, 2021 at 09:08:36PM +0200, Mauro Carvalho Chehab wrote:
quoted
Em Sat, 5 Jun 2021 12:11:09 -0300
Nícolas F. R. A. Prado [off-list ref] escreveu:
  
quoted
Hi Mauro,

On Sat, Jun 05, 2021 at 03:17:59PM +0200, Mauro Carvalho Chehab wrote:  
quoted
As discussed at:
	https://lore.kernel.org/linux-doc/871r9k6rmy.fsf@meer.lwn.net/ (local)

It is better to avoid using :doc:`foo` to refer to Documentation/foo.rst, as the
automarkup.py extension should handle it automatically, on most cases.

There are a couple of exceptions to this rule:

1. when :doc:  tag is used to point to a kernel-doc DOC: markup;
2. when it is used with a named tag, e. g. :doc:`some name <foo>`;

It should also be noticed that automarkup.py has currently an issue:
if one use a markup like:

	Documentation/dev-tools/kunit/api/test.rst
	  - documents all of the standard testing API excluding mocking
	    or mocking related features.

or, even:

	Documentation/dev-tools/kunit/api/test.rst
	    documents all of the standard testing API excluding mocking
	    or mocking related features.
	
The automarkup.py will simply ignore it. Not sure why. This patch series
avoid the above patterns (which is present only on 4 files), but it would be
nice to have a followup patch fixing the issue at automarkup.py.    
What I think is happening here is that we're using rST's syntax for definition
lists [1]. automarkup.py ignores literal nodes, and perhaps a definition is
considered a literal by Sphinx. Adding a blank line after the Documentation/...
or removing the additional indentation makes it work, like you did in your
2nd and 3rd patch, since then it's not a definition anymore, although then the
visual output is different as well.  
A literal has a different output. I think that this is not the case, but I 
didn't check the python code from docutils/Sphinx.  
Okay, I went in deeper to understand the issue and indeed it wasn't what I
thought. The reason definitions are ignored by automarkup.py is because the main
loop iterates only over nodes that are of type paragraph:

    for para in doctree.traverse(nodes.paragraph):
        for node in para.traverse(nodes.Text):
            if not isinstance(node.parent, nodes.literal):
                node.parent.replace(node, markup_refs(name, app, node))

And inspecting the HTML output from your example, the definition name is inside
a <dt> tag, and it doesn't have a <p> inside. So in summary, automarkup.py will
only work on elements which are inside a <p> in the output.

Yeah, that's what I was suspecting, based on the comments.

Maybe something similar to the above could be done also for some
non-paragraph data. By looking at:

	https://docutils.sourceforge.io/docs/ref/doctree.html

It says that the body elements are:

	admonition, attention, block_quote, bullet_list, caution, citation, 
	comment, compound, container, danger, definition_list, doctest_block, 
	enumerated_list, error, field_list, figure, footnote, hint, image, 
	important, line_block, literal_block, note, option_list, paragraph, 
	pending, raw, rubric, substitution_definition, system_message, 
	table, target, tip, warning
Ok, I went through each one by searching the term on [1] and inspecting the
element to see if it contained a <p> or not. The vast majority did. These are
the ones I didn't find there or didn't make sense:

	comment
	container
	image
	pending
	raw
	substitution_definition
	system_message
	target

We can safely ignore them. And these are the ones that matter and don't have
paragraphs:

	1. literal_block
	2. doctest_block
	3. definition_list
	4. field_list
	5. option_list
	6. line_block

1 and 2 are literals, so we don't care about them.

3 is the one you noticed the issue with. It's worth mentioning that the
definition term doesn't have a paragraph, but its definition does (as can be
checked by inspecting [2]).

4 is basically the same as 3, the rst syntax is different but the output is the
same. That said, I believe we only use those to set options at the top of the
file, like in translations, and I can't see automarkup being useful in there.

5 is similar to 3 and 4, but the term is formatted using <kbd>, so it's like a
literal and therefore not relevant.

6 is useful just to preserve indentation, and I'm pretty sure we don't use it in
the docs.

So in the end, I think the only contenders to be added to automarkup are
definition lists, and even then I still think we should just substitute those
definition lists with alternatives like you did in your patches. Personally I
don't see much gain in using definitions instead of a simple paragraph. But if
you really think it's an improvement in some way, it could probably be added to
automarkup in the way you described.

Thanks,
Nícolas

[1] https://sphinx-rtd-theme.readthedocs.io/en/stable/index.html
[2] https://sphinx-rtd-theme.readthedocs.io/en/stable/demo/lists_tables.html?highlight=definition%20list#definition-lists
So, perhaps a similar loop for definition_list would do the trick,
but maybe automarkup should also look at other types, like enum lists,
notes (and their variants, like error/warning) and footnotes.

No idea how this would affect the docs build time, though.
quoted
Only applying the automarkup inside paragraphs seems like a good decision (which
covers text in lists and tables as well), so unless there are other types of
elements without paragraphs where automarkup should work, I think we should just
avoid using definition lists pointing to documents like that.
Checking the code or doing some tests are needed for us to be sure about what
of the above types docutils don't consider a paragraph.

Thanks,
Mauro
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