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

[Josh Triplett]

On Mon, Dec 26, 2016 at 02:43:00PM +0000, Ximin Luo wrote:
> 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.

This seems like the right answer.  (We could experiment with attempting
to get those architectures working in experimental, while having the
package in unstable that will eventually propagate to stable only target
the first-tier architectures.)

I'd love to have support for all Debian architectures, since I'd like to
write more infrastructure code in Rust.  However, I think anyone wanting
to see this working consistently on their architecture needs to do that
work upstream.