[PATCH 1/2] doc/sphinx: Enable keep_warnings

[Daniel Vetter]

On Tue, Jul 19, 2016 at 5:25 PM, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> On Tue, Jul 19, 2016 at 4:59 PM, Markus Heiser
> <markus.heiser at darmarit.de> wrote:
>>
>> Am 19.07.2016 um 13:42 schrieb Daniel Vetter <daniel.vetter at ffwll.ch>:
>>
>>> Unfortunately warnings generated after parsing in sphinx can end up
>>> with entirely bogus files and line numbers as sources. Strangely for
>>> outright errors this is not a problem. Trying to convert warnings to
>>> errors also doesn't fix it.
>>>
>>> The only way to get useful output out of sphinx to be able to root
>>> cause the error seems to be enabling keep_warnings, which inserts
>>> a System Message into the actual output. Not pretty at all, but I
>>> don't really want to fix up core rst/sphinx code, and this gets the job
>>> done meanwhile.
>>
>> Hi Daniel,
>>
>> may I misunderstood you. Did you really get more or different warnings
>> if you include them into the output with "keep_warnings"?
>>
>> The documentation says:
>>
>>   "Regardless of this setting, warnings are always written
>>    to the standard error stream when sphinx-build is run."
>>
>> see http://www.sphinx-doc.org/en/stable/config.html#confval-keep_warnings
>>
>> Or did you not run "make cleandoc" first? Sphinx caches the doctrees
>> and reports markup errors only when you rebuild the cache.
>> The cache is also rebuild if you touch one of the source, e.g.
>> the drivers/gpu/drm/drm_crtc.c or the rst-file where the drm_crtc.c
>> is referred by a kernel-doc directive .. these dependence sometimes
>> confuse me .. when I missed log messages, I clean the cache e.g. by
>> target cleandocs.
>
> Yes I'm aware that sphinx it's WARNINGs when doing a partially
> rebuild, this is something entirely different. I didn't get more or
> less warnings this way, but keep_warning = True seems to be the only
> way to get reasonable information about them. Without that I get
> warnings (for included kernel-doc) where the source file is the .rst
> file that pulls in the kernel doc, and the line number is entirely
> bogus (often past the end of the containing .rst).
>
> With this I can at least then open the generated .html file, search
> for the System Message and figure out (by looking at the surrounding
> context) where the error really is from.
>
> Strangely this only happens for WARNING. If I manged the kerneldoc
> enough to upset sphinx into generating an ERROR, the line numbers and
> source files are correct.
>
> See patch 2/2 in this series for examples of such WARNINGs: Mostly
> it's unbalanced _ * or `` annotations that confuse sphinx/rst a bit.
> If you want to play around with the gpu sphinx conversion to reproduce
> these locall you can grab the drm-intel-nightly branch from
>
> https://cgit.freedesktop.org/drm-intel
>
> It already includes Jon's latest docs-next branch.

btw, I couldn't check this since I didn't figure out how to intercept
the parsed rst tree and view it, but I think what's going on is:
- The source file for these warnings is .rst file containing the
kernel-doc directive. This seems to be a bug in sphinx/docutils since
we never use that file name when appending files at all.
- The line number looks like it's just counting the inserted
kernel-doc lines as part of the containing .rst file. At least
changing the content_offset in nested_parse seems to suggest that this
is the start line (e.g. adding 10k there results in all bogus WARNING
line numbers being increased by 10k). And adding more blank lines at
the beginning of the inserted kernel-doc rst also increases the
reported lines. But not when inserting blank lines at the end (i.e. it
seems like it's being reset after each directive again).

All that suggest to me this is a sphinx-internal issue, and google
sugggests there's lots of errata around line reporting. Hence why I
went with this. But of course a proper fix would be awesome! Just a
bit outside of what I think I can pull off ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch