E.1. Language changes in Rust 1.95.0¶

• Stabilize if let guards on match arms

• irrefutable_let_patterns lint no longer lints on let chains

  • Lints are outside the scope of the FLS.

• Support importing path-segment keywords with renaming

• Stabilize ppc inline assembly

  • The target is outside the scope of the FLS.

• 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

  • This implementation-specifc behavior is outside the scope of the FLS.

• Make operational semantics of pattern matching independent of crate and module

E.2. Language changes in Rust 1.94.0¶

• Impls and impl items inherit dead_code lint level of the corresponding traits and trait items

  • Lints are outside the scope of the FLS.

• Stabilize additional 29 RISC-V target features including large portions of the RVA22U64 / RVA23U64 profiles

  • The target is outside the scope of the FLS.

• Add warn-by-default unused_visibilities lint for visibility on const _ declarations

  • Lints are outside the scope of the FLS.

• Update to Unicode 17

  • Changed paragraph: 2.3:5

• Avoid incorrect lifetime errors for closures

  • The mechanics of the borrow checker are outside the scope of the FLS.

E.3. Language changes in Rust 1.93.1¶

• Don’t try to recover keyword as non-keyword identifier

  • Bug fix in the compiler without visible ramifications.

• Fix clippy::panicking_unwrap false-positive on field access with implicit deref

  • Lints are outside the scope of the FLS.

• Revert “Update wasm-related dependencies in CI”

  • The target is outside the scope of the FLS.

E.4. Language changes in Rust 1.93.0¶

• Stabilize several s390x vector-related target features and the is_s390x_feature_detected! macro

  • The target is outside the scope of the FLS.

• Stabilize declaration of C-style variadic functions for the system ABI

  • Changed paragraph: 21.1:7

  • New paragraphs:

    • 9:26

    • 9:27

• Emit error when using some keyword as a cfg predicate

  • This bug was not documented in the FLS.

• Stabilize asm_cfg

  • Changed syntax:

    • AssemblyCodeBlock

    • AsmArguments

    • GlobalAsmArguments

  • New syntax:

    • AssemblyAttributeAbiClobber

    • AssemblyAttributeAssemblyOption

    • AssemblyAttributeRegisterArgument

    • AssemblyTemplate

  • New glossary entry: inline assembly argument

  • New paragraphs:

    • 22.7:2

    • 22.7:3

    • 22.7:4

• During const-evaluation, support copying pointers byte-by-byte

  • Already covered by the classification of constant expressions.

• 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)

  • Removed paragraphs:

    • Paragraph fls_ooOYxhVh8hZo

    • Paragraph fls_zkNFeBLy80UA

    • Paragraph fls_VhzGfnWg7YrG

    • Paragraph fls_qC6L0km0ZMFI

    • Paragraph fls_ibYKKQdB2tDn

    • Paragraph fls_dQdSxf8kOgbi

• Add warn-by-default const_item_interior_mutations lint to warn against calls which mutate interior mutable const items

  • Lints are outside the scope of the FLS.

• Add warn-by-default function_casts_as_integer lint

  • Lints are outside the scope of the FLS.

E.5. FLS corrections¶

• Deduplicate historically reused paragraph IDs in the glossary.

  • Corrected glossary discriminant type paragraph ID: - old reused ID: fls_t4yeovFm83Wo - new unique ID: fls_kqdvWGi9cglm

  • Corrected glossary local trait paragraph ID: - old reused ID: fls_I9JaKZelMiby - new unique ID: fls_H5vkbMFvzrFs

E.6. Language changes in Rust 1.92.0¶

• Document MaybeUninit representation and validity

  • This is not a language change.

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

  • This lifted restriction was not documented in the FLS.

• Prefer item bounds of associated types over where-bounds for auto-traits and Sized

  • This entry is a fix for a regression which existed only in the development versions of the Rust toolchain. These toolchains are outside the scope of the FLS.

• Do not materialize X in “[X; 0]” when X is unsizing a const

  • This behavior was not documented in the FLS.

• Support combining #[track_caller] and #[no_mangle] (requires every declaration specifying #[track_caller] as well)

  • This lifted restriction was not documented in the FLS.

• Make never type lints never_type_fallback_flowing_into_unsafe and dependency_on_unit_never_type_fallback deny-by-default

  • Lints are outside the scope of the FLS.

• Allow specifying multiple bounds for same associated item, except in trait objects

  • This lifted restriction was not documented in the FLS.

• Slightly strengthen higher-ranked region handling in coherence

  • The lifted restriction was not documented in the FLS.

• 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.

  • Lints are outside the scope of the FLS.

E.7. Language changes in Rust 1.91.1¶

This release has no language changes.

E.8. Language changes in Rust 1.91.0¶

• Lower pattern bindings in the order they’re written and base drop order on primary bindings’ order

  • Changed paragraphs:

    • 15.9:5

    • 5:11

    • 5:14

    • 5.13:4

    • 5.13:5

    • 5.13:6

    • 5.13:7

    • 5.13:8

    • 5.13:9

    • 5.13:10

    • 5.13:11

    • 5.13:12

    • 5.13:13

    • 5.13:14

    • 5.13:16

  • New paragraphs:

    • 15.9:3

    • 15.9:17

    • 15.9:18

    • 15.9:19

    • 15.9:20

    • 5:2

    • 5:9

    • 5:10

    • 5:13

    • 5.13:1

    • 5.13:3

  • Removed paragraph: Paragraph fls_67ajub7d2b4c

• 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.

  • Changed paragraphs:

    • 4.7.1:4

    • 21.1:12

    • 9:18

  • New paragraphs:

    • 9:19

    • 9:20

    • 9:21

    • 9:22

    • 9:23

    • 9:24

    • 9:28

    • 9:29

    • 9:30

    • 9:31

    • 9:25

    • 9:17

    • 21.1:13

    • 21.1:15

    • 21.1:20

    • 21.1:23

    • 21.1:16

• Add dangling_pointers_from_locals lint to warn against dangling pointers from local variables

  • Lints are outside the scope of the FLS.

• Upgrade semicolon_in_expressions_from_macros from warn to deny

  • Lints are outside the scope of the FLS.

• Stabilize LoongArch32 inline assembly

  • The target is outside the scope of the FLS

• Add warn-by-default integer_to_ptr_transmutes lint against integer-to-pointer transmutes

  • Lints are outside the scope of the FLS.

• Stabilize ‘sse4a’ and ‘tbm’ target features

  • Changed syntax: Feature

  • New paragraphs:

    • 13.2.1.4:48

    • 13.2.1.4:50

• Add ‘target_env = “macabi”’ and ‘target_env = “sim”’ cfgs as replacements for the target_abi cfgs with the same values.

  • Configuration options are environment-specific and not exhaustive.

E.9. Language changes in Rust 1.90.0¶

• Split up the unknown_or_malformed_diagnostic_attributes lint

  • Lints are outside the scope of the FLS.

• Allow constants whose final value has references to mutable/external memory, but reject such constants as patterns

  • This lifted restriction was not documented in the FLS.

  • The restriction on patterns is documented in 5.5:5.

  • New paragraph: 6.1.2:34

    • Paragraph 6.1.2:34 replaces Paragraph fls_6g7c1kjrmfnr and Paragraph fls_hkbwa8xx2fwx.

  • New paragraphs:

    • Paragraph fls_ooOYxhVh8hZo

    • Paragraph fls_zkNFeBLy80UA

    • Paragraph fls_VhzGfnWg7YrG

    • Paragraph fls_ibYKKQdB2tDn

    • Paragraph fls_dQdSxf8kOgbi

    • Paragraph fls_qC6L0km0ZMFI

• Allow volatile access to non-Rust memory, including address 0

  • Lints are outside the scope of the FLS.

E.10. Language changes in Rust 1.89.0¶

• Stabilize explicitly inferred const arguments (feature(generic_arg_infer))

  • New paragraphs:

    • 12.1:35

    • 12.1:36

    • 12.1:37

    • 12.1:38

  • Changed paragraph: 4.4.1:3

• Add a warn-by-default mismatched_lifetime_syntaxes lint.

  • Lints are outside the scope of the FLS.

• Expand unpredictable_function_pointer_comparisons to also lint on function pointer comparisons in external macros

  • Lints are outside the scope of the FLS.

• Make the dangerous_implicit_autorefs lint deny-by-default

  • Lints are outside the scope of the FLS.

• Stabilize the avx512 target features

  • Changed syntax: Feature

  • New paragraphs:

    • 13.2.1.4:9

    • 13.2.1.4:10

    • 13.2.1.4:11

    • 13.2.1.4:12

    • 13.2.1.4:13

    • 13.2.1.4:14

    • 13.2.1.4:15

    • 13.2.1.4:16

    • 13.2.1.4:17

    • 13.2.1.4:18

    • 13.2.1.4:19

    • 13.2.1.4:20

    • 13.2.1.4:21

    • 13.2.1.4:22

    • 13.2.1.4:23

    • 13.2.1.4:24

    • 13.2.1.4:25

    • 13.2.1.4:26

    • 13.2.1.4:27

    • 13.2.1.4:32

    • 13.2.1.4:51

    • 13.2.1.4:52

• Stabilize these target features for x86: kl, widekl

  • Changed syntax: Feature

  • New paragraphs:

    • 13.2.1.4:33

    • 13.2.1.4:53

• Stabilize these target features for x86: sha512, sm3, sm4

  • Changed syntax: Feature

  • New paragraphs:

    • 13.2.1.4:40

    • 13.2.1.4:41

    • 13.2.1.4:42

• Stabilize these LoongArch target features: f, d, frecipe, lasx, lbt, lsx, lvz

  • The target is outside the scope of the FLS.

• Remove i128 and u128 from improper_ctypes_definitions lint

  • Lints are outside the scope of the FLS.

• Stabilize repr128 (#[repr(u128), #repr(i128)])

  • The FLS already documented the semantics.

• Allow #![doc(test(attr(..))) everywhere

  • Documentation tests are outside the scope of the FLS.

• Extend temporary lifetime extension to also go through tuple struct and tuple variant constructors

  • Changed paragraphs:

    • Paragraph fls_DQaCUkskfXzk

    • 15.8.1:7

  • New paragraphs:

    • 15.8.1:6

    • 15.8.1:14

• extern “C” functions on the wasm32-unknown-unknown target now have a standards compliant ABI

  • The target is outside the scope of the FLS.

E.11. Language changes in Rust 1.88.0¶

• Stabilize let_chains feature in the 2024 edition

  • The 2024 edition is outside the scope of the FLS.

• Stabilize naked_functions feature

  • New sections: Attribute naked

  • Changed paragraphs:

    • 22:2

    • 22.7:1

    • 22.7:7

    • 22.6:2

    • 22.6:15

  • New paragraphs:

    • 13.2:5

    • 13.2.6.12:8

    • 22.3:18

    • 22.7:9

    • 22.7:10

    • Changed syntax:

      • BuiltinAttributeContent

      • RegisterArgument

      • RegisterExpression

  • New syntax: SymPathExpression

• Stabilize cfg_boolean_literals feature

  • Changed syntax: ConfigurationPredicate

• Fully de-stabilize the #[bench] attribute

  • Unstable features are outside the scope of the FLS.

• Add warn-by-default dangerous_implicit_autorefs lint against implicit autoref of raw pointer dereference

  • Lints are outside the scope of the FLS.

• Add invalid_null_arguments lint to prevent invalid usage of null pointers

  • Lints are outside the scope of the FLS.

• Change trait impl candidate preference for builtin impls and trivial where-clauses.

  • Trait impl candidate preferences of the compiler are outside the scope of the FLS.

• Check types of generic const parameter defaults

  • This bug was not documented in the FLS.

E.12. Language changes in Rust 1.87.0¶

• Stabilize asm_goto feature

  • New section: Label block

• Allow parsing open beginning ranges (..EXPR) after unary operators: ! - *

  • This lifted restriction was not documented in the FLS.

• Don’t require method impls for methods with “Self: Sized” bounds in impls for unsized types

  • This lifted restriction was not documented in the FLS.

• Stabilize feature(precise_capturing_in_traits) allowing use<…> bounds on return position impl Trait in traits (RPITIT)

  • This lifted restriction was not documented in the FLS.

E.13. Language changes in Rust 1.86.0¶

• Stabilize upcasting trait objects to supertraits.

  • New paragraph: 4.12.3:30

• Allow safe functions to be marked with the #[target_feature] attribute.

  • Changed paragraph: 13.2.1.4:1

• The missing_abi lint now warns-by-default.

  • Lints are outside the scope of the FLS.

• 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.

  • Lints are outside the scope of the FLS.

• More pointers are now detected as definitely not-null based on their alignment in const eval.

  • The concrete semantics of constant evaluation is not described in the FLS.

• Empty repr() attribute applied to invalid items are now correctly rejected.

  • This bug was not documented in the FLS.

• Inner attributes, #![test] and #![rustfmt::skip], are no longer accepted in more places than intended.

  • Tool-related attributes are outside the scope of the FLS.

  • The incorrect semantics of #![test] were not documented in the FLS.

E.14. Language changes in Rust 1.85.0¶

• The 2024 Edition is now stable.

  • The 2024 edition is outside the scope of the FLS.

• Stabilize async closures

  • New paragraphs:

    • 6.14:2

    • 6.14:6

  • Changed syntax: ClosureExpression

• Stabilize `#[diagnostic::do_not_recommend]`

  • Tool-related attributes are outside the scope of the FLS.

• Add `unpredictable_function_pointer_comparisons` lint to warn against function pointer comparisons

  • Lints are outside the scope of the FLS.

• Lint on combining `#[no_mangle]` and `#[export_name]` attributes.

  • Lints are outside the scope of the FLS.

E.15. Language changes in Rust 1.84.0¶

• Allow `#[deny]` inside `#[forbid]` as a no-op

  • Lints are outside the scope of the FLS.

• Show a warning when `-Ctarget-feature` is used to toggle features that can lead to unsoundness due to ABI mismatches

  • Conforming tool usage is outside the scope of the FLS.

• Use the next-generation trait solver in coherence

  • The trait solver is outside the scope of the FLS.

• Allow coercions to drop the principal of trait objects

  • Changed paragraph: 4.12.3:29

• Support `/` as the path separator for `include!()` in all cases on Windows

  • This restriction of the include macro was not documented in the FLS.

• Taking a raw ref (`raw (const|mut)`) of a deref of a pointer (`*ptr`) is now safe

  • Changed paragraph: 6.5.3:4

• Stabilize s390x inline assembly

  • This target is outside the scope of the FLS.

• Stabilize Arm64EC inline assembly

  • This target is outside the scope of the FLS.

• Lint against creating pointers to immediately dropped temporaries

  • Lints are outside the scope of the FLS.

• Execute drop glue when unwinding in an `extern “C”` function

  • This lifted restriction was not documented in the FLS.

E.16. Language changes in Rust 1.83.0¶

• Stabilize `&mut`, `*mut`, `&Cell`, and `*const Cell` in const.

  • Changed paragraphs:

    • 6.1.2:12

    • Paragraph fls_6g7c1kjrmfnr

    • Paragraph fls_hkbwa8xx2fwx

  • Removed paragraph: Paragraph fls_ox6sgl9n43g2

• Allow creating references to statics in `const` initializers.

  • This lifted restriction was not documented in the FLS.

• Implement raw lifetimes and labels (`’r#ident`).

  • Changed syntax: Lifetime

• Define behavior when atomic and non-atomic reads race.

  • Already covered by the definition of data race.

• Non-exhaustive structs may now be empty.

  • Changed paragraphs:

    • 4.12.6:8

    • 4.12.6:11

  • Removed paragraph: Paragraph fls_2CWUWbYT9KcT

• Disallow implicit coercions from places of type `!`

  • The FLS does not specify type inference to such a degree.

• `const extern` functions can now be defined for other calling conventions.

  • This lifted restriction was not documented in the FLS.

• Stabilize `expr_2021` macro fragment specifier in all editions.

  • Changed syntax: MacroFragmentSpecifier

  • Changed paragraphs:

    • 20.4.1.2:6

    • 20.1.1:6

• The `non_local_definitions` lint now fires on less code and warns by default.

  • Lints are outside the scope of the FLS.

E.17. Language changes in Rust 1.82.0¶

• Don’t make statement nonterminals match pattern nonterminals

  • Parsing behavior of non-terminals within declarative macros is outside the scope of the FLS.

• Patterns matching empty types can now be omitted in common cases

  • New section: Visible Emptiness

  • Changed paragraphs:

    • 5.1:2

    • 5.1:3

    • 5.5:9

    • 5.5:10

    • 5.7:2

    • 5.10:8

• Enforce supertrait outlives obligations when using trait impls

  • The FLS does not specify type inference to such a degree.

• `addr_of(_mut)!` macros and the newly stabilized `&raw (const|mut)` are now safe to use with all static items

  • Library-defined macros are outside the scope of the FLS.

  • &raw (const|mut) appears as a new feature separately below.

• size_of_val_raw: for length 0 this is safe to call

  • Library-defined functions are outside the scope of the FLS.

• Reorder trait bound modifiers *after* `for<…>` binder in trait bounds

  • Changed syntax: TraitBound

• Stabilize opaque type precise capturing (RFC 3617)

  • Changed syntax:

    • ImplTraitTypeSpecification

    • ImplTraitTypeSpecificationOneBound

  • New syntax:

    • UseCaptures

    • UseCapturesGenericArgs

    • UseCapturesGenericArg

  • New paragraphs:

    • 4.8.1:7

    • 4.14:15

    • 4.8.1:8

    • 4.8.1:9

• Stabilize `&raw const` and `&raw mut` operators (RFC 2582)

  • New section: Raw Borrow Expression

  • New paragraph: 6.1.4:23

• Stabilize unsafe extern blocks (RFC 3484)

  • New syntax: ItemSafety

  • Changed syntax:

    • FunctionQualifierList

    • StaticDeclaration

    • WeakKeyword

  • Changed paragraphs:

    • 2.6.3:5

    • 9:46

    • 21.2:1

    • 21.3:2

    • 21.4:3

  • New paragraphs:

    • 21.2:2

    • 7.2:5

    • 9:47

  • Removed paragraph Paragraph fls_iaimuqcclstl

• Stabilize nested field access in `offset_of!`

  • Library-defined macros are outside the scope of the FLS.

• Do not require `T` to be live when dropping `[T; 0]`

  • The mechanics of the borrow checker are outside the scope of the FLS.

• Stabilize `const` operands in inline assembly

  • New syntax: ConstRegisterExpression

  • New paragraphs:

    • 22.3:13

    • 22.3:16

    • 22.3:17

• Stabilize floating-point arithmetic in `const fn`

  • New paragraph: 6.5:2

  • Removed paragraph: Paragraph fls_9mrrosm8jnn7

• Stabilize explicit opt-in to unsafe attributes

  • New section: Attribute unsafe

• Document NaN bit patterns guarantees

  • New paragraph: 4.3.3.1:3

E.18. Language changes in Rust 1.81.0¶

• Abort on uncaught panics in `extern “C”` functions.

  • The mechanics of unwinding are outside the scope of the FLS.

• Fix ambiguous cases of multiple `&` in elided self lifetimes.

  • Changed paragraph: 4.14.3.1:15

  • New paragraph: 4.14.3.1:6

• Stabilize `#[expect]` for lints (RFC 2383), like `#[allow]` with a warning if the lint is _not_ fulfilled.

  • New paragraph: 13.2:19

• Change method resolution to constrain hidden types instead of rejecting method candidates.

  • The FLS does not specify type inference to such a degree.

• Bump `elided_lifetimes_in_associated_constant` to deny.

  • Lints are outside the scope of the FLS.

• `offset_from`: always allow pointers to point to the same address.

  • This lifted restriction was not documented in the FLS.

• Allow constraining opaque types during subtyping in the trait system.

  • The FLS does not specify type inference to such a degree.

• Allow constraining opaque types during various unsizing casts.

  • The FLS does not specify type inference to such a degree.

• Deny keyword lifetimes pre-expansion.

  • No change: the FLS already specifies this restriction in Lifetime

E.19. Language changes in Rust 1.80.0¶

• Document maximum allocation size

  • New paragraphs:

    • 7:2

    • 7:3

    • 7:4

    • 7:11

    • 7:12

    • 7:13

• Allow zero-byte offsets and ZST read/writes on arbitrary pointers

  • This lifted restriction was not documented in the FLS.

• Support C23’s variadics without a named parameter

  • This lifted restriction was not documented in the FLS.

• Stabilize `exclusive_range_pattern` feature

  • Changed syntax: RangePattern

  • New syntax: ExclusiveRangePattern

  • Changed paragraph: 5.6:16

  • New paragraphs:

    • 5.6:4

    • 5.6:11

    • 5.13.5:4

E.20. Language changes in Rust 1.79.0¶

• Stabilize inline `const {}` expressions.

  • New section: Const Blocks

• Prevent opaque types being instantiated twice with different regions within the same function.

  • Already described in 4.12.2:51.

• Stabilize WebAssembly target features that are in phase 4 and 5.

  • This target is outside the scope of the FLS.

• Add the `redundant_lifetimes` lint to detect lifetimes which are semantically redundant.

  • Lints are outside the scope of the FLS.

• Stabilize the `unnameable_types` lint for public types that can’t be named.

  • Lints are outside the scope of the FLS.

• Enable debuginfo in macros, and stabilize `-C collapse-macro-debuginfo` and `#[collapse_debuginfo]`.

  • New section: Attribute collapse_debuginfo

• Propagate temporary lifetime extension into `if` and `match` expressions.

  • New paragraphs:

    • 15.8.1:10

    • 15.8.1:11

    • 15.8.1:12

• Restrict promotion of `const fn` calls.

  • Already described in 7.4.1:6.

• Warn against refining impls of crate-private traits with `refining_impl_trait` lint.

  • Lints are outside the scope of the FLS.

• Stabilize associated type bounds (RFC 2289).

  • New paragraph: 12.3:5

• Stabilize importing `main` from other modules or crates.

  • This lifted restriction was not documented in the FLS.

  • While updating the FLS to account for this feature, we realized that the way the FLS described crate types was incorrect. We rectified this:

    • New section: Program Entry Point

    • Changed glossary entries:

      • binary crate

      • library crate

      • proc-macro crate

    • New glossary entry: crate type

    • Changed paragraphs:

      • 18.3:5

      • 18.3:9

      • 18.3:8

    • New paragraphs:

      • 18.3:2

      • 18.3:3

      • 18.3:4

      • 18.3:6

    • Moved paragraph: 18.7:2

• Check return types of function types for well-formedness

  • The mechanism of trait resolution is outside the scope of the FLS.

• Rework `impl Trait` lifetime inference

  • New paragraphs:

    • 4.8.1:3

    • 4.8.1:4

    • 4.8.1:5

• Change inductive trait solver cycles to be ambiguous

  • The trait solver is outside the scope of the FLS.

E.21. Language changes in Rust 1.78.0¶

• Stabilize `#[cfg(target_abi = …)]`

  • Configuration options are outside the scope of the FLS.

• Stabilize the `#[diagnostic]` namespace and `#[diagnostic::on_unimplemented]` attribute

  • Tool-related attributes are outside the scope of the FLS.

• Make async-fn-in-trait implementable with concrete signatures

  • The FLS already documented the semantics.

• Make matching on NaN a hard error, and remove the rest of `illegal_floating_point_literal_pattern`

  • New paragraph: 5.3:3

• static mut: allow mutable reference to arbitrary types, not just slices and arrays

  • This lifted restriction was not documented in the FLS.

• Extend `invalid_reference_casting` to include references casting to bigger memory layout

  • Lints are outside the scope of the FLS.

• Add `non_contiguous_range_endpoints` lint for singleton gaps after exclusive ranges

  • Lints are outside the scope of the FLS.

• Add `wasm_c_abi` lint for use of older wasm-bindgen versions

  • Lints are outside the scope of the FLS.

• Update `indirect_structural_match` and `pointer_structural_match` lints to match RFC

  • Lints are outside the scope of the FLS.

• Make non-`PartialEq`-typed consts as patterns a hard error

  • Already described in 5.5:4.

• Split `refining_impl_trait` lint into `_reachable`, `_internal` variants

  • Lints are outside the scope of the FLS.

• Remove unnecessary type inference when using associated types inside of higher ranked `where`-bounds

  • The FLS does not document type inference to such a degree.

• Weaken eager detection of cyclic types during type inference

  • The FLS does not specify type inference to such a degree.

• `trait Trait: Auto {}`: allow upcasting from `dyn Trait` to `dyn Trait + Auto`

  • New paragraph: 4.12.3:29

E.22. language changes in Rust 1.77.0¶

• Reveal opaque types within the defining body for exhaustiveness checking.

  • Concrete type introspection is outside the scope of the FLS.

• Stabilize C-string literals.

  • New section: C String Literals

• Stabilize THIR unsafeck.

  • This is not a language change.

• Add lint `static_mut_refs` to warn on references to mutable statics.

  • Lints are outside the scope of the FLS.

• Support async recursive calls (as long as they have indirection).

  • This lifted restriction was not documented in the FLS.

• Undeprecate lint `unstable_features` and make use of it in the compiler.

  • Lints are outside the scope of the FLS.

• Make inductive cycles in coherence ambiguous always.

  • The trait solver is outside the scope of the FLS.

• Get rid of type-driven traversal in const-eval interning, only as a future compatibility lint for now.

  • This lifted restriction was not documented in the FLS.

• Deny braced macro invocations in let-else.

  • New paragraph: 8.1:4