Rust 1.85-1.93 Knowledge Patch
Claude's baseline knowledge covers Rust through 1.84. This skill provides features from 1.85 (Feb 2025) through 1.93 (Jan 2026).
Quick Reference
Edition 2024 (Major Changes)
| Change | Migration |
|---|---|
unsafe extern "C" {} | Add unsafe to extern blocks |
#[unsafe(no_mangle)] | Wrap unsafe attrs in unsafe() |
unsafe {} in unsafe fns | Explicit unsafe blocks required |
static mut denied | Use atomics/sync primitives |
gen reserved | Rename identifiers |
set_var/remove_var unsafe | Wrap in unsafe {} |
Let chains (Edition 2024 only):
rust
if let Some(x) = opt && x > 0 && let Some(y) = other { ... }
See references/edition-2024.md for full migration guide.
Async
- •Async closures:
async || {}withAsyncFn,AsyncFnMut,AsyncFnOncetraits - •
OnceLock::wait: Block until initialization completes - •
RwLockWriteGuard::downgrade: Write → read lock without releasing
See references/async-and-concurrency.md.
Collections
| Method | Types |
|---|---|
extract_if | Vec, LinkedList, HashMap, HashSet, BTreeMap, BTreeSet |
pop_if | Vec |
pop_front_if / pop_back_if | VecDeque |
get_disjoint_mut | slices, HashMap |
Cell::update | Cell |
Tuple collection: (Vec<_>, Vec<_>) = iter.map(\|x\| (a, b)).collect()
See references/collections.md.
Integers
| Method | Description |
|---|---|
midpoint | Exact midpoint without overflow |
is_multiple_of | Divisibility check |
unbounded_shl/shr | Return 0 on overflow |
cast_signed/unsigned | Bit reinterpretation |
*_sub_signed | Subtract signed from unsigned |
strict_* | Panic on overflow (release too) |
carrying_*/borrowing_* | Extended precision arithmetic |
unchecked_* | UB on overflow (perf-critical) |
See references/integers-and-arithmetic.md.
Slices & Arrays
- •Chunking:
as_chunks,as_rchunks→(&[[T; N]], &[T]) - •Conversion:
slice.as_array::<N>()→Option<&[T; N]> - •Boundaries:
str.ceil_char_boundary(n),floor_char_boundary(n) - •Const:
reverse,rotate_left,rotate_right
See references/slices-and-arrays.md.
Strings & Paths
- •
Path::file_prefix: Filename without ANY extensions - •
PathBuf::add_extension: Add without replacing - •
OsStr::display: Lossy UTF-8 display - •
String::into_raw_parts: Decompose to(ptr, len, cap)
See references/strings-and-paths.md.
Pointers & Memory
- •Trait upcasting:
&dyn Derived→&dyn Baseautomatic - •
NonNullprovenance:from_ref,without_provenance,expose_provenance - •
MaybeUninitslices:write_copy_of_slice,assume_init_ref - •Zeroed constructors:
Box::new_zeroed(),Arc::new_zeroed()
See references/pointers-and-memory.md.
Assembly & SIMD
- •Safe
#[target_feature]: No unsafe needed for decorated fns - •
asm!labels: Jump to Rust code blocks - •
asm!cfg:#[cfg(...)]on individual lines - •Naked functions:
#[unsafe(naked)]+naked_asm!
See references/assembly-and-simd.md.
I/O
- •
io::pipe(): Cross-platform anonymous pipes - •
File::lock/unlock: Advisory file locking - •
i128/u128in FFI: No more warnings
See references/io-and-process.md.
Misc
- •
Result::flatten:Result<Result<T,E>,E>→Result<T,E> - •
fmt::from_fn: Display from closure - •
Duration::from_mins/hours: Convenience constructors - •Const
TypeId::of: Compile-time type IDs - •Const float rounding:
floor,ceil,roundin const
See references/misc-apis.md.
Cargo
- •LLD default (x86_64 Linux): Faster linking
- •
cargo publish --workspace: Multi-crate publishing - •Auto cache cleaning: 3mo network, 1mo local
See references/cargo-and-tooling.md.
Reference Files
Detailed documentation in references/:
| File | Contents |
|---|---|
edition-2024.md | Full Edition 2024 migration guide |
async-and-concurrency.md | Async closures, locks, atomics |
integers-and-arithmetic.md | All integer methods |
collections.md | extract_if, pop_if, disjoint_mut |
slices-and-arrays.md | Chunking, conversion, const ops |
strings-and-paths.md | Path/String APIs |
pointers-and-memory.md | Upcasting, provenance, MaybeUninit |
assembly-and-simd.md | asm!, target_feature, naked fns |
io-and-process.md | Pipes, FFI, file locking |
misc-apis.md | Floats, Duration, formatting, cfg |
cargo-and-tooling.md | LLD, workspace publish, cache |