Rust 1.85-1.93 Knowledge Patch

Quick Reference

Edition 2024 (Major Changes)

unsafe extern "C" {}

unsafe

#[unsafe(no_mangle)]

unsafe()

unsafe {}

static mut

gen

set_var

remove_var

unsafe {}

if let Some(x) = opt && x > 0 && let Some(y) = other { ... }

references/edition-2024.md

Async

• Async closures:

  async || {}

  with

  AsyncFn

  ,

  AsyncFnMut

  ,

  AsyncFnOnce

  traits

• OnceLock::wait

  : Block until initialization completes

• RwLockWriteGuard::downgrade

  : Write → read lock without releasing

references/async-and-concurrency.md

Collections

extract_if

pop_if

pop_front_if

pop_back_if

get_disjoint_mut

Cell::update

(Vec<_>, Vec<_>) = iter.map(\|x\| (a, b)).collect()

references/collections.md

Integers

midpoint

is_multiple_of

unbounded_shl/shr

cast_signed/unsigned

*_sub_signed

strict_*

carrying_*/borrowing_*

unchecked_*

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

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)

references/strings-and-paths.md

Pointers & Memory

• Trait upcasting:

  &dyn Derived

  →

  &dyn Base

  automatic

• NonNull

  provenance:

  from_ref

  ,

  without_provenance

  ,

  expose_provenance

• MaybeUninit

  slices:

  write_copy_of_slice

  ,

  assume_init_ref

• Zeroed constructors:

  Box::new_zeroed()

  ,

  Arc::new_zeroed()

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!

references/assembly-and-simd.md

I/O

• io::pipe()

  : Cross-platform anonymous pipes

• File::lock/unlock

  : Advisory file locking

• i128/u128

  in FFI: No more warnings

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

  ,

  round

  in const

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

references/cargo-and-tooling.md

Reference Files

references/

edition-2024.md

async-and-concurrency.md

integers-and-arithmetic.md

collections.md

slices-and-arrays.md

strings-and-paths.md

pointers-and-memory.md

assembly-and-simd.md

io-and-process.md

misc-apis.md

cargo-and-tooling.md