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

[Jonathan Kew]

On 16/05/2019 12:31, Ulrike Fischer wrote:
> Am Mon, 13 May 2019 17:52:17 +0200 schrieb François Patte:
> 
>> I have just made a fresh install of texlive 2019 and encountered a
>> problem with the diacritical marks of romanized sanskrit.
> 

Do the 'dev2' script tables in FreeSerif include positioning features 
for the various combining diacritics on Latin characters? I'm guessing 
not, in which case it's unsurprising that the results will be poor if 
you present it with accented Latin, yet request Devanagari shaping behavior.

I'd expect romanized Sanskrit should be typeset with script=latn, or 
with no explicit script specification.

JK

> (copied from f.c.t.t):
> 
> One can see it with plain xetex too, and it is not the font (I'm
> forcing it to 2018), et it is not xdvipdfmx (it happens with tl19
> and tl18 version). So it is quite probably an xetex engine bug.
> 
> A plain xetex example:
> 
> \XeTeXtracingfonts=1
> \font\test="[C:/texlive/2018/texmf-dist/fonts/opentype/public/gnu-freefont/FreeSerif.otf]/OT:script=dev2;"
> \test  ā ī ū ṛ ṝ ḷ ḹ ṭ ḍ ṅ ś ṣ ḥ
> \bye
> 
> 
> Comparing the versions gives
> 2019:
> Compiled with ICU version 63.1; using 63.1
> Compiled with zlib version 1.2.11; using 1.2.11
> Compiled with FreeType2 version 2.9.1; using 2.9.1
> Compiled with Graphite2 version 1.3.13; using 1.3.13
> Compiled with HarfBuzz version 2.3.1; using 2.3.1
> Compiled with libpng version 1.6.36; using 1.6.36
> Compiled with poppler version 0.68.0
> Compiled with fontconfig version 2.13.1; using 2.13.1
> 
> 2018:
> Compiled with ICU version 61.1; using 61.1
> Compiled with zlib version 1.2.11; using 1.2.11
> Compiled with FreeType2 version 2.9.1; using 2.9.1
> Compiled with Graphite2 version 1.3.11; using 1.3.11
> Compiled with HarfBuzz version 1.7.6; using 1.7.6
> Compiled with libpng version 1.6.34; using 1.6.34
> Compiled with poppler version 0.64.0
> Compiled with fontconfig version 2.13.0; using 2.13.0
> 
> The first suspect is HarfBuzz.
> 
> 
> 
>