[gentoo-dev] dev-python/cryptography to use rust, effectively killing alpha, hppa, ia64, m68k, s390

[Michał Górny]

Hi,

FYI the developers of dev-python/cryptography decided that Rust is going
to be mandatory for 1.5+ versions.  It's unlikely that they're going to
provide LTS support or security fixes for the old versions.

Since cryptography is a very important package in the Python ecosystem,
and it is an indirect dependency of Portage, this means that we will
probably have to entirely drop support for architectures that are not
supported by Rust.

According to upstream platform support information [1], this probably
means (eventually) entirely removing the following architectures:
- alpha (stable)
- hppa (stable)
- ia64 (stable)
- m68k (exp)
- s390 (except for s390x, exp)

Furthermore, the Gentoo Rust packages are missing support
for the following platforms, apparently supported upstream:
- mips (exp)
- ppc (32) (stable)
- sparc (stable)
- s390x (exp)
- riscv (stable)

Apparently it's non-trivial to bootstrap Rust on these platforms,
so it's unclear when Gentoo is going to start providing Rust on them.

I've raised a protest on the cryptography bug tracker [2] but apparently
upstream considers Rust's 'memory safety' more important than ability to
actually use the package.

Honestly, I don't think it likely that Rust will gain support for these
platforms.  This involves a lot of work, starting with writing a new
LLVM backend and getting it accepted (getting new code into LLVM is very
hard unless you're doing that on behalf one of the big companies).  You
can imagine how much effort that involves compared to rewriting the new
code from Cryptography into C.

If we can't convince upstream, I'm afraid we'll either have to drop
these architectures entirely or fork Cryptography.


[1] https://doc.rust-lang.org/nightly/rustc/platform-support.html
[2] https://github.com/pyca/cryptography/issues/5771

-- 
Best regards,
Michał Górny