Language
- Add allow-by-default raw_borrows_via_referenceslint that checks for references that decay immediately into raw borrows
- Extend unconditional_paniclint to function calls that panic when the chunks/windows size is zero
- Stabilize C-variadic function definitions
- Stabilize the ability to use #[unsafe(naked)]functions to define C-variadic functions (#![feature(c_variadic_naked_functions)]).
- Trait methods are now resolved on an adjusted never type (producing a FCW)
- Coerce from inference variables to trait objects if the inference variable is related via subtyping to a type that is known to be Sized
- Stabilize #[my_macro] mod foo;. This allows outlined modules (mod foo;) anywhere in the body of a custom attribute or derive macro.
- Fix the overflowing_literalslint with repeated negation. For instance, it will now no longer lint on--128_i8, which is already detected by thearithmetic_overflowlint.
- Add POSIX symbols to the invalid_runtime_symbol_definitionsandsuspicious_runtime_symbol_definitionslints
- Lint unused #[path]attributes on inline modules
- Enable unreachable_cfg_select_predicateslint as part ofunusedlint group
- Stabilize passing 128-bit integers via vector registers with asm!on x86
- Explicitly document that some allocations are allowed to grow in-place (but none are allowed to shrink)
- We now guarantee that the contents of an UnsafeCellcan be accessed without going throughget
- Account for globally enabled target features in global_asm!
- Warn if an invalid docattribute is used on a macro invocation
Compiler
- Convert -Ctarget-cpuinto a target-modifier for AVR, AMDGCN and NVPTX
- Enable static_position_independent_executableson all gnu targets
- When providing a suggestion about a missing method, rustc now prefers an exactly matching name from a doc alias attribute over a similarity search from other method names. If your new users sometimes expect a method under a different name, adding a doc alias will now help them find it via rustc suggestions, in addition to helping them find it via rustdoc search: When suggesting method names, prefer exact doc aliases over similar names
Platform Support
Refer to Rust's platform support page for more information on Rust's tiered platform support.
Libraries
- Iteration on RangeInclusive(a..=branges) is now optimized better in some circumstances. As a side effect of this, the behavior ofRangeInclusivevalues that has already been exhausted (as an iterator) has changed. For example, the return values ofstart()andend()on such ranges may return different values, and using such ranges as slice indexes may have different behavior. These behaviors were not guaranteed to be stable, so these changes are considered to not be breaking changes.
- Relax transmute_copyto accept?Sizedtypes
- Update transmute_copyto use a non-unwinding panic
- Don't escape U+FF9E and U+FF9F in escape_debug_ext
- Re-export core::fmt::NumBufferinalloc(andstd)
Stabilized APIs
- IntoIteratorfor- Box<[T; N]>
- IntoIteratorfor- &Box<[T; N]>
- IntoIteratorfor- &mut Box<[T; N]>
- VecDeque::retain_back
- core::ffi::VaList
- Box::into_non_null
- Box::from_non_null
- Vec::into_parts
- Vec::from_parts
- core::mem::size_of_val_raw
- core::mem::align_of_val_raw
- core::alloc::Layout::for_value_raw
- String::from_utf8_lossy_owned
- string::FromUtf8Error::into_utf8_lossy
- FusedIterator for StepBy<I>
- std::fs::set_times
- std::fs::set_times_nofollow
Cargo
- Add a new built-in profile debug. This is a preparation for transitioning thedevprofile away from debugging to give a saner default for faster development iterations. Currently there is no difference betweendevanddebugprofiles. docs #17214
- Workspace members on edition 2024 or later can now override an inherited workspace dependency's default-featuresfield. For example,serde = { workspace = true, default-features = false }now turns off default features even when the workspace definition enables them. On earlier editions,default-features = falseis ignored with a warning. (RFC 3945) #17126
See also the full Cargo changelog
Rustdoc
- Add new unused_footnote_definitionrustdoc lint
- Smarter filtering of trait impls yields performance improvements of 20% on average and up to 40% on some real-world crates. (1, 2, 3, 4, 5)
Compatibility Notes
- Fully deprecate the legacy integral modules. For example, std::i32::MAXshould be accessed viai32::MAXinstead.
- Upgrade no_mangle_generic_itemsinto hard error
- The Pin::new_uncheckedhas had its safety invariants changed slightly
- Do not promote references to extern statics
- Ensure that the inferred types of letpatterns typecheck
- hermit/fs: Return unsupported()instead offrom_raw_os_error(22)
- Fixed a bug where #[repr(simd)]was accidentally allowed on macro invocations on stable Rust
- Abort const-eval when there are generics in the type of the value being produced
- Attributes not applying to anything are now an error in code blocks in doc comments
- Box::leak: tell people to avoid unleaking
- PowerPC inline ASM: Fix scalar floats being in the wrong vector lane on little endian
- Do not take doc(cfg())into account when filtering doctests
- Infer anonymous lifetimes in the types of associated consts as 'static
- Macros that expand to a semicolon now produce a warning lint (semicolon_in_expressions_from_non_local_macros) even when the macro comes from another crate. Previously, such warnings only appeared for macros from the same crate, to avoid showing warnings that can't be fixed locally; however, this masked problems, as integration tests from the crate providing the macro get compiled as a separate crate, so tests often wouldn't reveal this issue. If you encounter a lint like this, please make sure to report it to the crate providing the macro so they can fix it; don't just silence it in your own crate.
- In Cargo, incremental compilation is now disabled by default when running in CI. CI is detected via the CIenvironment variable. #17220
Internal Changes
These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools.