bug#51658: [PATCH] Haiku port (again)

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> AFAIU, the Haiku developers only support GCC for compiling C++ code, as
>> they have a requirement to keep support for old BeOS software, which
>> depends on the GCC ABI.
>
> And for a good reason.  Then I think you should remove the part of
> configure.ac that looks for other C++ compilers, as that is entirely
> unnecessary, and probably will always be.

Thanks, done.

> The other platforms have past history, which Haiku doesn't.  And we
> plan on removing more old backends in the future; for example
> Uniscribe for Windows will die soon enough because MS deprecated it,
> and it is not being developed anymore, so falls behind in supporting
> new scripts and features.

I understand now.  Thanks.

> OK, let's go with two.  I understand that both will use HarfBuzz?  I'd
> prefer not to have backends that use other shaping engines, unless
> Haiku has some shaping engine that is better than HarfBuzz.

The haikufont backend will use whatever shaping engine is used by the
App Server (the window server on Haiku).  Right now, it can't do any
fancy shaping, but the Haiku developers plan to add HarfBuzz in the
future.

Once that is done, then the haikufont backend will support HarfBuzz
without any further work.

> I hope you will reconsider.  Having a niche platform with 3 font
> backends is really too much.  Especially since Emacs 29 learned to
> display Emoji now, and we are talking about adding decent support for
> ligatures, both of which require a shaping engine.

OK, so WDYT about keeping haikufont and Cairo support?  Please let me
know, and I'll update the patch.  Thanks in advance!