Re: Prefer luatex for documentation

[Werner LEMBERG]

> Sorry, luatex is like 10yrs old, what's the need for xetex again?

Some issues that potentially speak against using luatex:

* LuaTeX's OpenType support is still in flux and sometimes buggy.  The
  future is probably luatex-hb, using the 'HarfBuzz' library for
  OpenType font handling.

* The main target of LuaTeX is not LaTeX but ConTeXt, which means that
  some features (speak: extensions) are probably not as much tested.

* AFAIK, `luatex` is *much* slower than `pdftex`.

> Maybe I could justify pdftex (I really don't quite see it, but
> maybe) but xetex seems just arbitrary... Or do you mean for a
> transition period?

We changed to XeTeX because pdfTeX produces invalid PDF outlines if
non-ASCII characters are involved.  This is not a problem with pdfTeX
itself but due to lack of support in `texinfo.tex`.  At that time of
the switch, LuaTeX support wasn't ready – there was a `luatex` bug
that stalled further work for two months or so (until someone
suggested a workaround, see MR !1740).

> What's the oldest system that this Lilypond would be used on?
> What's the youngest texlive that will run on that system? That's
> your tex distro of reference.

TeXLive runs on virtually *all* systems, even old ones based on the
i386 chips.  This means there is no useful answer, AFAICS.


    Werner