Re: lang/rust on aarch64eb

[Havard Eidnes <he%NetBSD.org@localhost>]

> I don't NEED to run Rust on aarch64eb, but it'd be nice to be able to
> build pkgsrc packages that require Rust. I suppose if someone really
> wants it, they can take the time to make the snake eat itself.

The next hurdle you will encounter on aarch64eb is that there are too
many crates around which try to optimize their stuff using SIMD
operations, and there is a lot of assumptions around that "aarch64
means we use neon".  While architecturally, the neon SIMD instructions
are available in big-endian mode as well, code needs to be acutely
aware of the endian-ness to produce correct results.  Therefore, at
the time of writing, the neon SIMD extensions are not available in
rust on aarch64 in big-endian mode.

See e.g. https://github.com/rust-lang/stdarch/issues/1484.

If memory serves, there's a "half" crate which librsvg uses which
doesn't build on big-endian aarch64 for this reason, and this prevents
librsvg from building on that platform.

Ref. the above issue, there's room to contribute code to improve the
situation, but it'll be finicky and one should have a test rig to
verify that it works as intended, and my rust is near non-existent,
especially for crafting new code.

Regards,

- Håvard