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

[Steve White]

In these tests, I'm using:

FreeSerif from the SVN *before* my attempt at a "fix" (r. 3391)
Sanskrit 2003 1.05 August 22, 2004
Murty Sanskrit 001.001

I found the particular way that the font is set in the source has a big effect.
I have no idea what is "right".  But one produces better results.
In the files pg.tex and pg2.tex, the first does it as in the original posting;
the second does it as in some examples of fontspec use that I had lying around.

Then I did tests on my stock system with Harfbuzz 1.7.2,  and then
on the system set up as described before with Harfbuzz 2.8.1.

The results all look different.  I see:

On the HB 1.7.2 system, with the test as in the original posting,
only Murty shows an issue, with the l-underdot-macron.

On the HB 1.7.2 system, with the modified test,
all three fonts look perfect.

On the HB 2.8.1 system, with the test as in the original posting,
all the fonts produce mangled results, with no apparent mark positioning.
Sanskrit 2003 has the macron replaced with a double vertical line.

On the HB 2.8.1 system, with the modified test, mark positioning seems
to be working for all three fonts, but again, Sanskrit 2003 has the macron
replaced with a double vertical line.

I think we have multiple issues here.  There may be font issues in the mix.

Cheers

On Sun, May 19, 2019 at 1:51 PM Steve White <stevan.white at gmail.com> wrote:
>
> 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:
> >
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > 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
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v2
> >
> > iEYEARECAAYFAlzZkqYACgkQdE6C2dhV2JVkugCZAbQpaV+czlcHQIqmAt2zQaRH
> > ux8AoL/MgTfryea9BwVP89f+0Rhrgobb
> > =TMQb
> > -----END PGP SIGNATURE-----
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