Some data points: 1. I was able to reproduce the failures on an amd64 build machine running and compiling i386 code as early as v0.7.11-2 (see logs at [1]). To reproduce, on Debian Testing, within said version's source code:
``` sbuild-createchroot --include=eatmydata --arch=i386 testing /srv/chroot/testing-i386-sbuild sbuild -d testing --host i386 --build i386 ``` 2. Apparently the relevant code did not change upstream between v0.7.25 and v0.7.26 - that is, when the tests started failing. 3. All tests pass in i386 emulation using rustup's latest rustc/cargo via `cargo test --all --target i686-unknown-linux-gnu`. In more detail: I cross-compiled for i386 from arm64 (yes, arm64, not amd64) and then ran the tests wrapped in qemu-i386. 4. All tests pass on amd64 compiling and running i386 code using rustup's latest rustc/cargo via `cargo test --all --target i686-unknown-linux-gnu`. I recently had a bug in rust-dysk [2] where i386 (and i386 only) tests passing with rustup's rustc/cargo (3. and 4. above) + not passing with the configuration in point 1. above + the upstream code involving floating point operations chained to casts was due to Debian's i386 rust target being compiled without SSE2 and thus having inconsistent floating point behavior [3] . What I'm seeing in rust-wide, and the nature of the crate itself, closely reminds me of that. If this is the case, then the bug is real, it is Debian-specific (in the sense that it would not show up on a vanilla i386 rust target with SSE2 enabled) and there may be not much the upstream developers can do. I was only able to fix that bug in rust-dysk because I could replace an entire chain of operations altogether, but the code there was far simpler than rust-wide's. What I really don't understand is why the tests started failing just recently in Debian's CI if I see them failing already for v0.7.11-2, especially given that the failing code did not change between v0.7.25 and v0.7.26 (which makes me think upstream is not the cause anyway). [1] https://paste.debian.net/hidden/0db6dbeb/ [2] https://github.com/Canop/dysk/pull/79 [3] https://github.com/rust-lang/rust/issues/114479
