Updatify / Rust | Release notes

• rustc: Fix miscompilation in LLVM optimization This backports an LLVM submodule bump to include the LLVM-side fix and a revert of the rustc change that is one known trigger for the bug. The rustc side revert should not be strictly necessary but is done out of abundance of caution.

Language

• Consider Result<T, Uninhabited> and ControlFlow<Uninhabited, T> to be equivalent to T for must use lint
• Add allow-by-default dead_code_pub_in_binary lint for unused pub items in binary crates
• Stabilize the div32, lam-bh, lamcas, ld-seq-sa and scq target features
• Stabilize cfg(target_has_atomic_primitive_alignment)
• Allow trailing self in imports in more cases

Platform Support

• nvptx64-nvidia-cuda: drop support for old architectures and old ISAs

Refer to Rust’s platform support page for more information on Rust’s tiered platform support.

Stabilized APIs

• Default for RepeatN
• Copy for ffi::FromBytesUntilNulError
• Send for std::fs::File on UEFI

• Cargo: fix timeout/retry behavior
• Cargo: apply patches for CVE-2025-15661, CVE-2026-55199, and CVE-2026-55200 to libssh2
• rustc: fix miscompilation in MIR optimization

Language

• Allow passing expr metavariable to cfg
• Always coerce never types in tuple expressions
• Avoid incorrect inference guidance of function arguments in rare cases
• Support s390x vector registers in inline assembly
• Allow using constants of type ManuallyDrop as patterns (fixing a regression introduced in 1.94.0)

Compiler

• Enable link relaxation feature for LoongArch Linux targets
• Update riscv64gc-unknown-fuchsia baseline to RVA22 + vector

Libraries

• Support iterating over ranges of NonZero integers
• refactor ‘valid for read/write’ definition: exclude null; add that as an exception on individual methods instead
• Fix SGX delayed host lookup via ToSocketAddr

Stabilized APIs

• assert_matches!

Language

• Stabilize if let guards on match arms
• irrefutable_let_patterns lint no longer lints on let chains
• Support importing path-segment keywords with renaming
• Stabilize inline assembly for PowerPC and PowerPC64
• const-eval: be more consistent in the behavior of padding during typed copies
• Const blocks are no longer evaluated to determine if expressions involving fallible operations can implicitly be constant-promoted.. Expressions whose ability to implicitly be promoted would depend on the result of a const block are no longer implicitly promoted.
• Make operational semantics of pattern matching independent of crate and module

Compiler

• Stabilize --remap-path-scope for controlling the scoping of how paths get remapped in the resulting binary
• Apply patches for CVE-2026-6042 and CVE-2026-40200 to vendored musl

Platform Support

• Fix std::thread::spawn on wasm32-wasip1-threads
• Remove new methods added to std::os::windows::fs::OpenOptionsExt The new methods were unstable, but the trait itself is not sealed and so cannot be extended with non-default methods.
• Clippy: fix ICE in match_same_arms
• Cargo: update tar to 0.4.45 This resolves CVE-2026-33055 and CVE-2026-33056. Users of crates.io are not affected. See blog for more details.

Language

• Impls and impl items inherit dead_code lint level of the corresponding traits and trait items
• Stabilize additional 29 RISC-V target features including large portions of the RVA22U64 / RVA23U64 profiles
• Add warn-by-default unused_visibilities lint for visibility on const _ declarations
• Update to Unicode 17
• Avoid incorrect lifetime errors for closures

Platform Support

• Add riscv64im-unknown-none-elf as a tier 3 target

Refer to Rust’s platform support page for more information on Rust’s tiered platform support.

Libraries

• Relax T: Ord bound for some BinaryHeap<T> methods.

Stabilized APIs

• <[T]>::array_windows
• <[T]>::element_offset
• LazyCell::get

• Don’t try to recover keyword as non-keyword identifier, fixing an ICE that especially affected rustfmt.
• Fix clippy::panicking_unwrap false-positive on field access with implicit deref.
• Revert “Update wasm-related dependencies in CI”, fixing file descriptor leaks on the wasm32-wasip2 target.

Language

• Stabilize several s390x vector-related target features and the is_s390x_feature_detected! macro
• Stabilize declaration of C-style variadic functions for the system ABI
• Emit error when using some keyword as a cfg predicate
• Stabilize asm_cfg
• During const-evaluation, support copying pointers byte-by-byte
• LUB coercions now correctly handle function item types, and functions with differing safeties
• Allow const items that contain mutable references to static (which is very unsafe, but not always UB)
• Add warn-by-default const_item_interior_mutations lint to warn against calls which mutate interior mutable const items
• Add warn-by-default function_casts_as_integer lint

Compiler

• Stabilize -Cjump-tables=bool. The flag was previously called -Zno-jump-tables.

Platform Support

Language

• Document MaybeUninit representation and validity

• Allow &raw [mut | const] for union field in safe code

• Prefer item bounds of associated types over where-bounds for auto-traits and Sized
• Do not materialize X in [X; 0] when X is unsizing a const
• Support combining #[track_caller] and #[no_mangle] (requires every declaration specifying #[track_caller] as well)
• Make never type lints never_type_fallback_flowing_into_unsafe and dependency_on_unit_never_type_fallback deny-by-default
• Allow specifying multiple bounds for same associated item, except in trait objects
• Slightly strengthen higher-ranked region handling in coherence
• The unused_must_use lint no longer warns on Result<(), Uninhabited> (for instance, Result<(), !>), or ControlFlow<Uninhabited, ()>. This avoids having to check for an error that can never happen.

Compiler

• Enable file locking support in illumos. This fixes Cargo not locking the build directory on illumos.
• Fix wasm_import_module attribute cross-crate. This fixes linker errors on WASM targets.

Language

• Lower pattern bindings in the order they’re written and base drop order on primary bindings’ order
• Stabilize declaration of C-style variadic functions for sysv64, win64, efiapi, and aapcs ABIs. This brings these ABIs in line with the C ABI: variadic functions can be declared in extern blocks but not defined.
• Add dangling_pointers_from_locals lint to warn against dangling pointers from local variables
• Upgrade semicolon_in_expressions_from_macros from warn to deny
• Stabilize LoongArch32 inline assembly
• Add warn-by-default integer_to_ptr_transmutes lint against integer-to-pointer transmutes
• Stabilize sse4a and tbm target features
• Add target_env = "macabi" and target_env = "sim" cfgs as replacements for the target_abi cfgs with the same values.

Compiler

• Don’t warn on never-to-any as casts as unreachable

Platform Support

Language

• Split up the unknown_or_malformed_diagnostic_attributes lint. This lint has been split up into four finer-grained lints, with unknown_or_malformed_diagnostic_attributes now being the lint group that contains these lints:
  1. unknown_diagnostic_attributes: unknown to the current compiler
  2. misplaced_diagnostic_attributes: placed on the wrong item
  3. malformed_diagnostic_attributes: malformed attribute syntax or options
  4. malformed_diagnostic_format_literals: malformed format string literal
• Allow constants whose final value has references to mutable/external memory, but reject such constants as patterns
• Allow volatile access to non-Rust memory, including address 0

Compiler

• Use lld by default on x86_64-unknown-linux-gnu.
• Tier 3 musl targets now link dynamically by default. Affected targets:
  • mips64-unknown-linux-muslabi64
  • powerpc64-unknown-linux-musl
  • powerpc-unknown-linux-musl
  • powerpc-unknown-linux-muslspe
  • riscv32gc-unknown-linux-musl
  • s390x-unknown-linux-musl
  • thumbv7neon-unknown-linux-musleabihf

Platform Support

Language

• Stabilize explicitly inferred const arguments (feature(generic_arg_infer))
• Add a warn-by-default mismatched_lifetime_syntaxes lint. This lint detects when the same lifetime is referred to by different syntax categories between function arguments and return values, which can be confusing to read, especially in unsafe code. This lint supersedes the warn-by-default elided_named_lifetimes lint.
• Expand unpredictable_function_pointer_comparisons to also lint on function pointer comparisons in external macros
• Make the dangerous_implicit_autorefs lint deny-by-default
• Stabilize the avx512 target features
• Stabilize kl and widekl target features for x86
• Stabilize sha512, sm3 and sm4 target features for x86
• Stabilize LoongArch target features f, d, frecipe, lasx, lbt, lsx, and lvz
• Remove i128 and u128 from improper_ctypes_definitions
• Stabilize repr128 (#[repr(u128)], #[repr(i128)])

Language

• Stabilize #![feature(let_chains)] in the 2024 edition. This feature allows &&-chaining let statements inside if and while, allowing intermixture with boolean expressions. The patterns inside the let sub-expressions can be irrefutable or refutable.
• Stabilize #![feature(naked_functions)]. Naked functions allow writing functions with no compiler-generated epilogue and prologue, allowing full control over the generated assembly for a particular function.
• Stabilize #![feature(cfg_boolean_literals)]. This allows using boolean literals as cfg predicates, e.g. #[cfg(true)] and #[cfg(false)].
• Fully de-stabilize the #[bench] attribute. Usage of #[bench] without #![feature(custom_test_frameworks)] already triggered a deny-by-default future-incompatibility lint since Rust 1.77, but will now become a hard error.
• Add warn-by-default dangerous_implicit_autorefs lint against implicit autoref of raw pointer dereference. The lint will be bumped to deny-by-default in the next version of Rust.

Language

• Stabilize asm_goto feature
• Allow parsing open beginning ranges (..EXPR) after unary operators !, -, and *.
• Don’t require method impls for methods with Self: Sized bounds in impls for unsized types
• Stabilize feature(precise_capturing_in_traits) allowing use<...> bounds on return position impl Trait in traits

Compiler

• x86: make SSE2 required for i686 targets and use it to pass SIMD types

Platform Support

• Remove i586-pc-windows-msvc target

Refer to Rust’s platform support page for more information on Rust’s tiered platform support.

Libraries

• Stabilize the anonymous pipe API
• Add support for unbounded left/right shift operations
• Print pointer metadata in Debug impl of raw pointers

Language

• Stabilize upcasting trait objects to supertraits.
• Allow safe functions to be marked with the #[target_feature] attribute.
• The missing_abi lint now warns-by-default.
• Rust now lints about double negations, to catch cases that might have intended to be a prefix decrement operator (--x) as written in other languages. This was previously a clippy lint, clippy::double_neg, and is now available directly in Rust as double_negations.
• More pointers are now detected as definitely not-null based on their alignment in const eval.
• Empty repr() attribute applied to invalid items are now correctly rejected.
• Inner attributes #![test] and #![rustfmt::skip] are no longer accepted in more places than intended.

Compiler

• Debug-assert that raw pointers are non-null on access.
• Change -O to mean -C opt-level=3 instead of -C opt-level=2 to match Cargo’s defaults.

• Fix the doctest-merging feature of the 2024 Edition.
• Relax some target_feature checks when generating docs.
• Fix errors in std::fs::rename on Windows 10, version 1607.
• Downgrade bootstrap cc to fix custom targets.
• Skip submodule updates when building Rust from a source tarball.

Language

• The 2024 Edition is now stable. See the edition guide for more details.
• Stabilize async closures See RFC 3668 for more details.
• Stabilize #[diagnostic::do_not_recommend]
• Add unpredictable_function_pointer_comparisons lint to warn against function pointer comparisons
• Lint on combining #[no_mangle] and #[export_name] attributes.

Compiler

• The unstable flag -Zpolymorphize has been removed, see https://github.com/rust-lang/compiler-team/issues/810 for some background.

Platform Support

• Promote powerpc64le-unknown-linux-musl to tier 2 with host tools

Refer to Rust’s platform support page for more information on Rust’s tiered platform support.

Libraries

• Panics in the standard library now have a leading library/ in their path

• Fix ICE 132920 in duplicate-crate diagnostics.
• Fix errors for overlapping impls in incremental rebuilds.
• Fix slow compilation related to the next-generation trait solver.
• Fix debuginfo when LLVM’s location discriminator value limit is exceeded.
• Fixes for building Rust from source:
  • Only try to distribute llvm-objcopy if llvm tools are enabled.
  • Add Profile Override for Non-Git Sources.
  • Resolve symlinks of LLVM tool binaries before copying them.
  • Make it possible to use ci-rustc on tarball sources.

Language

• Allow #[deny] inside #[forbid] as a no-op
• Show a warning when -Ctarget-feature is used to toggle features that can lead to unsoundness due to ABI mismatches
• Use the next-generation trait solver in coherence
• Allow coercions to drop the principal of trait objects
• Support / as the path separator for include!() in all cases on Windows
• Taking a raw ref (raw (const|mut)) of a deref of a pointer (*ptr) is now safe
• Stabilize s390x inline assembly
• Stabilize Arm64EC inline assembly
• Lint against creating pointers to immediately dropped temporaries
• Execute drop glue when unwinding in an extern "C" function

Compiler

• Add --print host-tuple flag to print the host target tuple and affirm the “target tuple” terminology over “target triple”

Language

• Stabilize &mut, *mut, &Cell, and *const Cell in const.
• Allow creating references to statics in const initializers.
• Implement raw lifetimes and labels ('r#ident).
• Define behavior when atomic and non-atomic reads race.
• Non-exhaustive structs may now be empty.
• Disallow implicit coercions from places of type !
• const extern functions can now be defined for other calling conventions.
• Stabilize expr_2021 macro fragment specifier in all editions.
• The non_local_definitions lint now fires on less code and warns by default.

Compiler

• Deprecate unsound -Csoft-float flag.
• Add many new tier 3 targets:
  • aarch64_unknown_nto_qnx700
  • arm64e-apple-tvos
  • armv7-rtems-eabihf

Language

• Don’t make statement nonterminals match pattern nonterminals
• Patterns matching empty types can now be omitted in common cases
• Enforce supertrait outlives obligations when using trait impls
• addr_of(_mut)! macros and the newly stabilized &raw (const|mut) are now safe to use with all static items
• size_of_val_raw: for length 0 this is safe to call
• Reorder trait bound modifiers after for<...> binder in trait bounds
• Stabilize + use<'lt> opaque type precise capturing (RFC 3617)
• Stabilize &raw const and &raw mut operators (RFC 2582)
• Stabilize unsafe extern blocks (RFC 3484)
• Stabilize nested field access in offset_of!
• Do not require T to be live when dropping [T; 0]
• Stabilize const operands in inline assembly
• Stabilize floating-point arithmetic in const fn

Language

• Abort on uncaught panics in extern "C" functions.
• Fix ambiguous cases of multiple & in elided self lifetimes.
• Stabilize #[expect] for lints (RFC 2383), like #[allow] with a warning if the lint is not fulfilled.
• Change method resolution to constrain hidden types instead of rejecting method candidates.
• Bump elided_lifetimes_in_associated_constant to deny.
• offset_from: always allow pointers to point to the same address.
• Allow constraining opaque types during subtyping in the trait system.
• Allow constraining opaque types during various unsizing casts.
• Deny keyword lifetimes pre-expansion.

Compiler

• Make casts of pointers to trait objects stricter.
• Check alias args for well-formedness even if they have escaping bound vars.
• Deprecate no-op codegen option -Cinline-threshold=....

• Fix miscompilation in the jump threading MIR optimization when comparing floats
• Revert changes to the dead_code lint from 1.80.0

Language

• Document maximum allocation size
• Allow zero-byte offsets and ZST read/writes on arbitrary pointers
• Support C23’s variadics without a named parameter
• Stabilize exclusive_range_pattern feature
• Guarantee layout and ABI of Result in some scenarios

Compiler

• Update cc crate to v1.0.97 allowing additional spectre mitigations on MSVC targets
• Allow field reordering on types marked repr(packed(1))
• Add a lint against never type fallback affecting unsafe code
• Disallow cast with trailing braced macro in let-else
• Expand for_loops_over_fallibles lint to lint on fallibles behind references.
• self-contained linker: retry linking without -fuse-ld=lld on CCs that don’t support it
• Do not parse CVarArgs (...) as a type in trait bounds

Language

• Stabilize inline const {} expressions.
• Prevent opaque types being instantiated twice with different regions within the same function.
• Stabilize WebAssembly target features that are in phase 4 and 5.
• Add the redundant_lifetimes lint to detect lifetimes which are semantically redundant.
• Stabilize the unnameable_types lint for public types that can’t be named.
• Enable debuginfo in macros, and stabilize -C collapse-macro-debuginfo and #[collapse_debuginfo].
• Propagate temporary lifetime extension into if and match expressions.
• Restrict promotion of const fn calls.
• Warn against refining impls of crate-private traits with refining_impl_trait lint.
• Stabilize associated type bounds (RFC 2289).
• Stabilize importing main from other modules or crates.
• Check return types of function types for well-formedness

Language

• Stabilize #[cfg(target_abi = ...)]
• Stabilize the #[diagnostic] namespace and #[diagnostic::on_unimplemented] attribute
• Make async-fn-in-trait implementable with concrete signatures
• Make matching on NaN a hard error, and remove the rest of illegal_floating_point_literal_pattern
• static mut: allow mutable reference to arbitrary types, not just slices and arrays
• Extend invalid_reference_casting to include references casting to bigger memory layout
• Add non_contiguous_range_endpoints lint for singleton gaps after exclusive ranges
• Add wasm_c_abi lint for use of older wasm-bindgen versions This lint currently only works when using Cargo.
• Update indirect_structural_match and pointer_structural_match lints to match RFC
• Make non-PartialEq-typed consts as patterns a hard error
• Split refining_impl_trait lint into _reachable, _internal variants

• CVE-2024-24576: fix escaping of Windows batch file arguments in std::process::Command

• Revert stripping debuginfo by default for Windows This fixes a regression in 1.77 by reverting to the previous default. Platforms other than Windows are not affected.
• Internal: Fix heading anchor rendering in doc pages

Language

• Reveal opaque types within the defining body for exhaustiveness checking.
• Stabilize C-string literals.
• Stabilize THIR unsafeck.
• Add lint static_mut_refs to warn on references to mutable statics.
• Support async recursive calls (as long as they have indirection).
• Undeprecate lint unstable_features and make use of it in the compiler.
• Make inductive cycles in coherence ambiguous always.
• Get rid of type-driven traversal in const-eval interning, only as a future compatibility lint for now.
• Deny braced macro invocations in let-else.

Compiler

• Include lint soft_unstable in future breakage reports.
• Make i128 and u128 16-byte aligned on x86-based targets.
• Use --verbose in diagnostic output.

Language

• Document Rust ABI compatibility between various types
• Also: guarantee that char and u32 are ABI-compatible
• Add lint ambiguous_wide_pointer_comparisons that supersedes clippy::vtable_address_comparisons

Compiler

• Lint pinned #[must_use] pointers (in particular, Box<T> where T is #[must_use]) in unused_must_use.
• Soundness fix: fix computing the offset of an unsized field in a packed struct
• Soundness fix: fix dynamic size/align computation logic for packed types with dyn Trait tail
• Add $message_type field to distinguish json diagnostic outputs
• Enable Rust to use the EHCont security feature of Windows
• Add tier 3 {x86_64,i686}-win7-windows-msvc targets
• Add tier 3 aarch64-apple-watchos target
• Add tier 3 arm64e-apple-ios & arm64e-apple-darwin targets

Language

• Stabilize async fn and return-position impl Trait in traits.
• Allow function pointer signatures containing &mut T in const contexts.
• Match usize/isize exhaustively with half-open ranges.
• Guarantee that char has the same size and alignment as u32.
• Document that the null pointer has the 0 address.
• Allow partially moved values in match.
• Add notes about non-compliant FP behavior on 32bit x86 targets.
• Stabilize ratified RISC-V target features.

Compiler

• Rework negative coherence to properly consider impls that only partly overlap.
• Bump COINDUCTIVE_OVERLAP_IN_COHERENCE to deny, and warn in dependencies.
• Consider alias bounds when computing liveness in NLL.
• Add the V (vector) extension to the riscv64-linux-android target spec.

• Resolved spurious STATUS_ACCESS_VIOLATIONs in LLVM
• Clarify guarantees for std::mem::discriminant
• Fix some subtyping-related regressions

Language

• Codify that std::mem::Discriminant<T> does not depend on any lifetimes in T
• Replace private_in_public lint with private_interfaces and private_bounds per RFC 2145. Read more in RFC 2145.
• Allow explicit #[repr(Rust)]
• closure field capturing: don’t depend on alignment of packed fields
• Enable MIR-based drop-tracking for async blocks
• Stabilize impl_trait_projections

Compiler

• stabilize combining +bundle and +whole-archive link modifiers
• Stabilize PATH option for --print KIND=PATH
• Enable ASAN/LSAN/TSAN for *-apple-ios-macabi
• Promote loongarch64-unknown-none* to Tier 2
• Add i686-pc-windows-gnullvm as a tier 3 target

Libraries

• Implement From<OwnedFd/Handle> for ChildStdin/out/err

Language

• Uplift clippy::fn_null_check lint as useless_ptr_null_checks.
• Make noop_method_call warn by default.
• Support interpolated block for try and async in macros.
• Make unconditional_recursion lint detect recursive drops.
• Future compatibility warning for some impls being incorrectly considered not overlapping.
• The invalid_reference_casting lint is now deny-by-default (instead of allow-by-default)

Compiler

• Write version information in a .comment section like GCC/Clang.
• Add documentation on v0 symbol mangling.
• Stabilize extern "thiscall" and "thiscall-unwind" ABIs.
• Only check outlives goals on impl compared to trait.
• Infer type in irrefutable slice patterns with fixed length as array.
• Discard default auto trait impls if explicit ones exist.
• Add several new tier 3 targets:

• Fix CVE-2023-38497: Cargo did not respect the umask when extracting dependencies
• Fix bash completion for users of Rustup
• Do not show suspicious_double_ref_op lint when calling borrow()
• Fix ICE: substitute types before checking inlining compatibility
• Fix ICE: don’t use can_eq in derive(..) suggestion for missing method
• Fix building Rust 1.71.0 from the source tarball

• Adjust codegen change to improve LLVM codegen
• rustdoc: Fix self ty params in objects with lifetimes
• Fix regression in compile times
• Resolve some ICE regressions in the compiler:
  • #115215
  • #115559

Language

• Replace const eval limit by a lint and add an exponential backoff warning
• expand: Change how #![cfg(FALSE)] behaves on crate root
• Stabilize inline asm for LoongArch64
• Uplift clippy::undropped_manually_drops lint
• Uplift clippy::invalid_utf8_in_unchecked lint as invalid_from_utf8_unchecked and invalid_from_utf8
• Uplift clippy::cast_ref_to_mut lint as invalid_reference_casting
• Uplift clippy::cmp_nan lint as invalid_nan_comparisons
• resolve: Remove artificial import ambiguity errors
• Don’t require associated types with Self: Sized bounds in dyn Trait objects

Compiler

• Remember names of cfg-ed out items to mention them in diagnostics
• Support for native WASM exceptions
• Add support for NetBSD/aarch64-be (big-endian arm64).

Language

• Stabilize raw-dylib, link_ordinal, import_name_type and -Cdlltool.
• Uplift clippy::{drop,forget}_{ref,copy} lints.
• Type inference is more conservative around constrained vars.
• Use fulfillment to check Drop impl compatibility

Compiler

• Evaluate place expression in PlaceMention, making let _ = patterns more consistent with respect to the borrow checker.
• Add --print deployment-target flag for Apple targets.
• Stabilize extern "C-unwind" and friends. The existing extern "C" etc. may change behavior for cross-language unwinding in a future release.
• Update the version of musl used on *-linux-musl targets to 1.2.3, enabling time64 on 32-bit systems.
• Stabilize debugger_visualizer for embedding metadata like Microsoft’s Natvis.
• Enable flatten-format-args by default.

Language

• Relax ordering rules for asm! operands
• Properly allow macro expanded format_args invocations to uses captures
• Lint ambiguous glob re-exports
• Perform const and unsafe checking for expressions in let _ = expr position.

Compiler

• Extend -Cdebuginfo with new options and named aliases This provides a smaller version of debuginfo for cases that only need line number information (-Cdebuginfo=line-tables-only), which may eventually become the default for -Cdebuginfo=1.
• Make unused_allocation lint against Box::new too
• Detect uninhabited types early in const eval
• Switch to LLD as default linker for {arm,thumb}v4t-none-eabi
• Add tier 3 target loongarch64-unknown-linux-gnu
• Add tier 3 target for i586-pc-nto-qnx700 (QNX Neutrino RTOS, version 7.0),

Language

• Deriving built-in traits on packed structs works with Copy fields.
• Stabilize the cmpxchg16b target feature on x86 and x86_64.
• Improve analysis of trait bounds for associated types.
• Allow associated types to be used as union fields.
• Allow Self: Autotrait bounds on dyn-safe trait methods.
• Treat str as containing [u8] for auto trait purposes.

Compiler

• Upgrade *-pc-windows-gnu on CI to mingw-w64 v10 and GCC 12.2.
• Rework min_choice algorithm of member constraints.
• Support true and false as boolean flags in compiler arguments.
• Default repr(C) enums to c_int size.

Libraries

• Implement the unstable DispatchFromDyn for cell types, allowing downstream experimentation with custom method receivers.

• Update the GitHub RSA host key bundled within Cargo. The key was rotated by GitHub on 2023-03-24 after the old one leaked.
• Mark the old GitHub RSA host key as revoked. This will prevent Cargo from accepting the leaked key even when trusted by the system.
• Add support for @revoked and a better error message for @cert-authority in Cargo’s SSH host key verification

• Fix miscompilation in produced Windows MSVC artifacts This was introduced by enabling ThinLTO for the distributed rustc which led to miscompilations in the resulting binary. Currently this is believed to be limited to the -Zdylib-lto flag used for rustc compilation, rather than a general bug in ThinLTO, so only rustc artifacts should be affected.
• Fix –enable-local-rust builds
• Treat $prefix-clang as clang in linker detection code
• Fix panic in compiler code

Language

• Stabilize default_alloc_error_handler This allows usage of alloc on stable without requiring the definition of a handler for allocation failure. Defining custom handlers is still unstable.
• Stabilize efiapi calling convention.
• Remove implicit promotion for types with drop glue

Compiler

• Change bindings_with_variant_name to deny-by-default
• Allow .. to be parsed as let initializer
• Add armv7-sony-vita-newlibeabihf as a tier 3 target
• Always check alignment during compile-time const evaluation
• Disable “split dwarf inlining” by default.
• Add vendor to Fuchsia’s target triple
• Enable sanitizers for s390x-linux

Libraries

• Loosen the bound on the Debug implementation of Weak.
• Make std::task::Context !Send and !Sync

• Fix interoperability with thin archives.
• Fix an internal error in the compiler build process.
• Downgrade clippy::uninlined_format_args to pedantic.

Language

• Make Sized predicates coinductive, allowing cycles.
• #[must_use] annotations on async fn also affect the Future::Output.
• Elaborate supertrait obligations when deducing closure signatures.
• Invalid literals are no longer an error under cfg(FALSE).
• Unreserve braced enum variants in value namespace.

Compiler

• Enable varargs support for calling conventions other than C or cdecl.
• Add new MIR constant propagation based on dataflow analysis.
• Optimize field ordering by grouping m*2^n-sized fields with equivalently aligned ones.
• Stabilize native library modifier verbatim.

Added, updated, and removed targets:

• Add a tier 3 target for PowerPC on AIX, powerpc64-ibm-aix.
• Add a tier 3 target for the Sony PlayStation 1, mipsel-sony-psx.

• Added validation of SSH host keys for git URLs in Cargo (CVE-2022-46176)

Language

• Permit specifying explicit discriminants on all repr(Int) enums

  #[repr(u8)]
  enum Foo {
      A(u8) = 0,
      B(i8) = 1,
      C(bool) = 42,
  }

• Allow transmutes between the same type differing only in lifetimes
• Change constant evaluation errors from a deny-by-default lint to a hard error
• Trigger must_use on impl Trait for supertraits This makes impl ExactSizeIterator respect the existing #[must_use] annotation on Iterator.
• Allow ..=X in patterns
• Uplift clippy::for_loops_over_fallibles lint into rustc
• Stabilize sym operands in inline assembly
• Update to Unicode 15
• Opaque types no longer imply lifetime bounds This is a soundness fix which may break code that was erroneously relying on this behavior.

Compiler

• Add armv5te-none-eabi and thumbv5te-none-eabi tier 3 targets

Language

• Error on as casts of enums with #[non_exhaustive] variants
• Stabilize let else
• Stabilize generic associated types (GATs)
• Add lints let_underscore_drop and let_underscore_lock from Clippy
• Stabilize breaking from arbitrary labeled blocks (“label-break-value”)
• Uninitialized integers, floats, and raw pointers are now considered immediate UB. Usage of MaybeUninit is the correct way to work with uninitialized memory.
• Stabilize raw-dylib for Windows x86_64, aarch64, and thumbv7a
• Do not allow Drop impl on foreign ADTs

Compiler

• Stabilize -Csplit-debuginfo on Linux
• Use niche-filling optimization even when multiple variants have data
• Associated type projections are now verified to be well-formed prior to resolving the underlying type
• Stringify non-shorthand visibility correctly