Rust: Next Solver Cleanup and LLVM 22 Baseline
The compiler team is removing old trait solver workarounds and test shims as the next-generation solver nears default, while raising the external LLVM minimum to version 22. Smaller compiler performance wins and diagnostic fixes round out the day.
Duration: PT2M15S
Episode overview
This episode is a short developer briefing from Rust.
It explains recent repository work in plain language.
- Show: Rust
- Published: 2026-10-03T13:11:50Z
- Audio duration: PT2M15S
Transcript excerpt
This excerpt keeps the crawler page concise. Listen to the episode or use the RSS feed for the full update.
Good morning, it's October 3rd, 2026.
Lead insight: Rust is clearing the final blockers for the next-generation trait solver, and raising its code generation baseline at the same time.
First theme: the old solver is on its way out. PR 163655 explicitly marks user interface tests that already pass under the new solver, so they no longer fail in comparison modes. Related work in PR 162332 preserves overflow in built-in field candidates so coherence correctly rejects overlapping implementations.…
Second theme: the LLVM floor is moving up. PR 163572 updates the minimum supported external LLVM to version 22, with stable support for 22 and 23. Paired with that, commit da51be1 emits the dereferenceable marker in more cases on newer LLVM, after upstream changes decoupled it from the no-free guarantee. Impact is…
Third: performance and everyday polish. Commit e0452e2 adds a single-entry parent cache for span data, described as a clear win across benchmarks for encoding and hashing. On the user side, PR 151793 adds relaxed multiply-add methods for all floating point types, letting the compiler choose fused or separate…
What's next: watch for follow-up test updates around the solver transition…
Nearby episodes from Rust
- Quieter Diagnostics and Solver Hardening
- Safer Diagnostics and Solver Caution
- Filesystem APIs and Compiler Tightening
- Library Stabilizations and Compiler Cleanup
- Forced Keywords Land, Diagnostics Get Sharper
- Weekly Recap - Compiler Cleanup Sets Up Const Generics Future
- Std Polish and Clearer Errors
- MIR Lifecycle Rework and Build Correctness