[XeTeX] bug in polyglossia/sanskrit? (problem with diacritical marks)

[Steve White]

Hi, all,

I have reproduced François' effect with FreeSerif, as well as
Dominik's effect with Sanskrit 2003.

I started with stock Linux Mint 19.1.
Then I installled TeXLive 2018 from the PPA of jonathonf/texlive-2018.
In the results of running xelatex on the sample, I did not see any
peculiarities,
(except one with Murty Sanskrit, which appears even with older libraries).
But xelatex -v reports that it is built with and using Harfbuzz 1.7.2.

Built Harfbuzz 2.4.8 from sources (after the usual cycles of
installing build requirements)
To run with the xelatex from the PPA, it is necessary to enable Graphite2
   ./configure --with-graphite2=yes
   make install
Now in a Bash session, type
   export $LD_LIBRARY_PATH=/usr/local/lib
in the same session,
   xelatex -v
will report that it is using Harfbuzz 2.8.1.

Now the same sample built with xelatex shows the problems originally reported.

It is clear that the behaviour of Harfbuzz has changed.  The question
is, is it for the better or the worse?
Maybe the new version is just stricter about enabling font features,
or maybe it has improved its emulation of Uniscribe.
Or it may be a bug.

Will continue to investigate.

On Mon, May 13, 2019 at 7:16 PM François Patte
<francois.patte at mi.parisdescartes.fr> wrote:
>
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> Bonjour,
>
> I have just made a fresh install of texlive 2019 and encountered a
> problem with the diacritical marks of romanized sanskrit.
>
> See this mwe (compile it with and without \setdefaultlanguage{sanskrit}) :
>
> \documentclass[a4paper,twoside,11pt]{book}
> \usepackage{fontspec}
> \usepackage{polyglossia}
> \setdefaultlanguage{sanskrit}
> \setmainfont{FreeSerif}
>
> \begin{document}
>   ā ī ū ṛ ṝ ḷ ḹ ṭ ḍ ṅ ś ṣ ḥ
> \end{document}
>
> When you enable \setdefaultlanguage{sanskrit}, the diacritical marks
> are awfull: macrons are moved on the right, dots under move on the
> left, the dot on the "i" remains with the macron...
>
> This did not occur with my previous 2018 version of texlive.
>
> Thank you for attention.
>
> - --
> François Patte
> UFR de mathématiques et informatique
> Laboratoire CNRS MAP5, UMR 8145
> Université Paris Descartes
> 45, rue des Saints Pères
> F-75270 Paris Cedex 06
> Tél. +33 (0)6 7892 5822
> http://www.math-info.univ-paris5.fr/~patte
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