New trait solver rollout and coherence checks

Jon and Ben discuss the highlights of the 1.81 through 1.84 releases of Rust.

This episode was recorded as part of a YouTube live stream on 2025-10-26, which you can still watch.

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Timestamps & referenced resources

[@01:58] - Rust 1.81

• [@02:05] - core::error::Error
  • Tracking issue for generic member access
  • build-std Rust project goal
• [@08:27] - New sort implementations
  • PR implementing the change
  • Repo with the research
• [@10:49] - #[expect(lint)]
• [@14:37] - Lint reasons
• [@16:18] - Stabilized APIs
  • [@16:34] - Duration::abs_diff
  • [@17:25] - hint::assert_unchecked
  • [@22:36] - fs::exists
• [@25:37] - Compatibility notes
  • [@20:40] - Split panic hook and panic handler arguments
  • [@23:00] - Abort on uncaught panics in extern "C" functions
  • [@27:01] - WASI 0.1 target naming changed
  • [@30:10] - Fix for CVE-2024-43402
    • CVE announcement

[@33:39] - Rust 1.82

• [@33:39] - cargo info
• [@35:06] - Apple target promotions
  • Platform support tiers
• [@40:10] - Precise capturing use<..> syntax
  • The Captures “trick”
  • Talk on impl Trait
• [@47:24] - Native syntax for creating a raw pointer
  • Pointers Are Complicated
  • Pointers Are Complicated II
  • Pointers Are Complicated III
• [@53:43] - Safe items with unsafe extern
• [@59:32] - Unsafe attributes
• [@1:03:44] - Omitting empty types in pattern matching
  • The never type
• [@1:11:33] - Floating-point NaN semantics and const
• [@1:17:41] - Constants as assembly immediates
• [@1:19:06] - Safely addressing unsafe statics
• [@1:22:56] - Stabilized APIs
  • [@1:23:03] - thread::Builder::spawn_unchecked
  • [@1:25:10] - Working with MaybeUninit
  • [@1:25:48] - Exposed SIMD intrinsics
• [@1:26:14] - Changelog deep-dive
  • [@1:26:26] - Rewrite binary search implementation

[@1:27:30] - Rust 1.83

• [@1:27:55] - New const capabilities
• [@1:31:50] - Stabilized APIs
  • [@1:32:06] - New io::ErrorKind variants
  • [@1:33:10] - Option::get_or_insert_default
  • [@1:34:56] - char::MIN
• [@1:35:48] - Changelog deep-dive
  • [@1:35:48] - Unicode 16 Emoji
  • [@1:39:51] - Sysroot trim-paths
  • [@1:41:31] - cargo update informs of outdated versions
  • [@1:42:43] - cargo --timings dark mode
  • [@1:43:15] - Checksum-based freshness in Cargo nightly

[@1:44:26] - Rust 1.84

• [@1:44:40] - Cargo considers Rust version for dependency version selection
• [@1:49:03] - Migration to the new trait solver begins
• [@1:51:47] - Strict provenance APIs
  • Pointers Are Complicated
  • Pointers Are Complicated II
  • Pointers Are Complicated III
  • Rust has provenance
  • Gankra’s write-up on raw pointer design
  • Strict provenance APIs tracking issue
• [@1:57:53] - Stabilized APIs
  • [@1:57:58] - <int>::isqrt
  • [@1:58:15] - core::ptr::dangling
• [@1:59:15] - Changelog deep-dive
  • [@1:59:15] - Include Cargo.lock in published crates
  • [@2:00:12] - wasm32-wasi target removed
  • [@2:01:06] - &raw *invalid_ptr is fine

Credits

Intro Theme: Aerocity

Audio Editing: synchis

Hosting Infrastructure: Jon Gjengset

Show Notes: Jon Gjengset

Hosts: Jon Gjengset and Ben Striegel