Bug 2499684
| Summary: | miscompilation that leads to segfaults with Rust 1.97.0 | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Fabio Valentini <decathorpe> |
| Component: | llvm | Assignee: | Tulio Magno Quites Machado Filho <tuliom> |
| Status: | CLOSED ERRATA | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | rawhide | CC: | dmalcolm, fedora-llvm-team, jakub, jchecahi, jistone, kkleine, npopov, petersen, scottt.tw, sergesanspaille, siddharth.kde, suraj.ghimire7, tbaeder, tstellar, tuliom |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | llvm-22.1.8-4.fc44 llvm-21.1.8-6.fc43 | Doc Type: | --- |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2026-07-23 01:20:43 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
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Description
Fabio Valentini
2026-07-13 14:39:37 UTC
I am not surprised that we are affected, but have you directly experienced issues in real code? "real" code? That is hard to say yet ... koschei hasn't yet rebuilt all packages with Rust 1.97.0 in rawhide - and it would only catch issues in crates that run tests and where tests actually run the problematic code paths. So far, I see only one package that newly fails to build with Rust 1.97.0, and it looks like that is only due to it expecting a specific enum discriminant representation: https://koschei.fedoraproject.org/package/rust-tracing-core?collection=f45 ---- metadata::tests::level_filter_reprs stdout ---- thread 'metadata::tests::level_filter_reprs' (332) panicked at src/metadata.rs:1119:13: assertion `left == right` failed: repr changed for LevelFilter::OFF left: 5 right: 18446744073709551615 And this looks more like a bug in tracing-core's side. RE tracing-core -- FWIW that is related to the Rust change that also revealed the LLVM bug, but in this case tracing-core is making an unfounded assumption. It has `struct LevelFilter(Option<Level>)`, and `const OFF = LevelFilter(None)`. The test has a mapping array that includes (LevelFilter::OFF, LevelInner::Error as usize + 1), which is assuming that `None` fills the niche in the next greater value not used by Level. This was never guaranteed, and Rust 1.97 started to prefer wrapping the other way, choosing -1 for None in this case. I proposed a backport to this issue for Rawhide at https://src.fedoraproject.org/rpms/llvm/pull-request/620 FEDORA-2026-597e8f9de1 (llvm-22.1.8-4.fc44) has been submitted as an update to Fedora 44. https://bodhi.fedoraproject.org/updates/FEDORA-2026-597e8f9de1 FEDORA-2026-597e8f9de1 has been pushed to the Fedora 44 testing repository. Soon you'll be able to install the update with the following command: `sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-597e8f9de1` You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-597e8f9de1 See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates. FEDORA-2026-597e8f9de1 (llvm-22.1.8-4.fc44) has been pushed to the Fedora 44 stable repository. If problem still persists, please make note of it in this bug report. FEDORA-2026-e617677805 (llvm-21.1.8-6.fc43) has been submitted as an update to Fedora 43. https://bodhi.fedoraproject.org/updates/FEDORA-2026-e617677805 FEDORA-2026-e617677805 has been pushed to the Fedora 43 testing repository. Soon you'll be able to install the update with the following command: `sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-e617677805` You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-e617677805 See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates. FEDORA-2026-e617677805 (llvm-21.1.8-6.fc43) has been pushed to the Fedora 43 stable repository. If problem still persists, please make note of it in this bug report. |