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Date:   Fri, 21 May 2021 14:19:52 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
To:     Akira Yokosawa <akiyks@gmail.com>
Cc:     Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] docs: sphinx-pre-install: Reword warning on installing
 cjk font
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Em Fri, 21 May 2021 18:00:00 +0900
Akira Yokosawa <akiyks@gmail.com> escreveu:

> Hi Mauro,
> 
> On Fri, 21 May 2021 09:54:42 +0200, Mauro Carvalho Chehab wrote:
> > HI Akira,
> > 
> > Em Fri, 21 May 2021 16:14:19 +0900
> > Akira Yokosawa <akiyks@gmail.com> escreveu:
> >   
> >> Installing a ckj font as recommended by the warning message causes
> >> generated latex code to have:
> >>
> >> 	% This is needed for translations
> >> 	\usepackage{xeCJK}
> >> 	\setCJKmainfont{Noto Sans CJK SC}
> >>
> >> in its preamble even for an English document.  
> > 
> > Yes. The same LaTeX configuration is applied to all documents.
> > 
> > While the standard Sphinx logic allows just one conf.py, there's
> > a logic on Linux that allows a per-directory configuration.
> > Perhaps it would be possible to set the font just for translations.
> > 
> > Yet, this can't be easily done per-translation - Italian
> > translation for instance doesn't need CJK fonts.  
> 
> Yes, the Italian part looks ugly with xeCJK.
> 
> >   
> >> The package "xeCJK" changes wide characters' appearance including
> >> apostrophe (single quote) and double quotes, and it changes line-break
> >> behavior with regard to the boundary of narrow and wide characters.
> >>
> >> This greatly degrades readability of English PDFs typeset by xelatex.  
> > 
> > Hmm... could you give an example where it looks ugly?
> > 
> > At least on the documents I use to check the PDF output, I was unable
> > to see any big issue.  
> 
> Appended are screenshots from RCU.pdf built with and without xeCJK.
> 
> They are built on Ubuntu Bionic based container with sphinx 2.4.4.
> 
> I think you can see the difference of how apostrophes are rendered.
> Line-break points are also affected by the widths of apostrophes.
> 
> Can you spot the difference?

Ok, now I understand what you're meaning. We need to double check
what's wrong there, as it doesn't make much sense to have a
"`  " character instead of "`" on those places, nor to change
the word's hyphenation logic.

> 
> BTW, on current docs-next, wich the CJK font installed, "make pdfdocs"
> stops while building s390.pdf.

That's weird.

> I needed to manually run "make latexdocs", then run
> "latexmk -xelatex RCU.tex" under Documentation/output/latex/ to get
> RCU.pdf.

Well, you can pass some options to latexmk when building a
pdf via an environment var (LATEXMKOPTS), like (untested):

	LATEXMKOPTS="-interaction=nonstopmode" make pdfdocs.

or change it to interactive mode, in order to show what part
of the s390.tex is causing the issue.

Thanks,
Mauro