[Pkg-rust-maintainers] Efficiently supporting (or not) other arches in the long term

[Ximin Luo]

Rust upstream does not regularly run tests for anything other than amd64 or i386:

https://forge.rust-lang.org/platform-support.html

This has resulted in the past few releases of Debian's rustc being held back from testing migration, due to arm64 breakages that we had to file upstream:

1.10.0 https://github.com/rust-lang/rust/pull/34889
1.11.0 https://github.com/rust-lang/rust/issues/36348
1.12.0 there probably was one but I can't remember it
1.13.0 https://github.com/rust-lang/rust/issues/37225
1.14.0 https://github.com/rust-lang/rust/issues/38612

We can't keep doing this long-term, I don't have time to chase these things every 6 weeks. And soon we might start supporting 7 new architectures, which will have their own test failures.

What shall we do about this? I think it's nice to support as many architectures as possible, and that is strongly encouraged by Debian - but upstream don't provide the same level of support. I'll suggest two options:

1) Totally drop support for non-first-tier architectures (i.e. not amd64/i386), because experience has shown that the tests break too often. True, most of the test failures have been trivial and the fix was to ignore them. However of them might be significant (these latest two from 1.14.0 look more serious) and I'm not qualified to judge all of them.

To do this, we would simply have to file a RM for arm64, and then our workload will be reduced.

2) Start releasing rust-beta to Debian experimental. Unlike nightly, beta is not supposed to change often and they only put in bugfixes here. This would be an ideal place to try to build on all of Debian's ~10 official architectures, then file bugs upstream for the failed tests. However, it's uncertain at this moment whether they will actually fix these bugs in time - they have 6 weeks before it's released as rust-stable.

We may or may not have time to cope with this, but I am ready to try it for the next few releases if you guys think it's a good idea.

X

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