Shapers included in the TeX Live builds of LuaHBTeX

[Bruno Voisin]

Hello,

Is there a simple way to list the HarfBuzz shapers included in the TeX Live builds of LuaHBTeX?

The fontspec doc lists 4 HarfBuzz renderers:

Renderer = Harfbuzz	-> corresponds to mode=harf in luaotfload
Renderer = OpenType	-> corresponds to mode=harf;shaper=ot
Renderer = Graphite	-> corresponds to mode=harf;shaper=graphite2
Renderer = AAT		-> corresponds to mode=harf;shaper=coretext_aat

On the Mac, using no explicit shaper or using shaper=ot does work. Trying either shaper=graphite2 or shaper=coretext_aat, I get

luaotfload | harf : Shaper failed.

Does this mean these two shapers aren't included? Must they be installed separately?

On the TL source repo there's a

https://tug.org/svn/texlive/trunk/Build/source/libs/graphite2/

so I was expecting the Graphite shaper to be included. Or is it just not included in Mac builds?

I tried to figure out a way to list the built-in shapers.

https://tug.org/svn/texlive/trunk/Build/source/texk/web2c/luatexdir/luaharfbuzz/README.md?revision=57915&view=markup

mentions

-- Shapers available
print("Shapers:", serpent.line({ harfbuzz.shapers() }, {comment = false}))

but I know nothing about Lua (ie, how to run this code with texlua on the command line, to get a list of the available shapers as output).

I tried \directlua in a TeX file, of course unsuccessfully. Besides, the above seems to require prior installation of something called "serpent".

Bruno Voisin
(Please cc the answer to me, I'm not subscribed to the list)