RUST-1.94.0 release notes and known issues

Summary

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 LazyCell::get_mut LazyCell::force_mut LazyLock::get LazyLock::get_mut LazyLock::force_mut impl TryFrom<char> for usize std::iter::Peekable::next_if_map std::iter::Peekable::next_if_map_mut x86 avx512fp16 intrinsics (excluding those that depend directly on the unstable f16 type) AArch64 NEON fp16 intrinsics (excluding those that depend directly on the unstable f16 type) f32::consts::EULER_GAMMA f64::consts::EULER_GAMMA f32::consts::GOLDEN_RATIO f64::consts::GOLDEN_RATIO These previously stable APIs are now stable in const contexts: f32::mul_add f64::mul_add Cargo Stabilize the config include key. The top-level include config key allows loading additional config files, enabling better organization, sharing, and management of Cargo configurations across projects and environments. docs #16284 Stabilize the pubtime field in registry index. This records when a crate version was published and enables time-based dependency resolution in the future. Note that crates.io will gradually backfill existing packages when a new version is published. Not all crates have pubtime yet. #16369 #16372 Cargo now parses TOML v1.1 for manifests and configuration files. Note that using these features in Cargo.toml will raise your development MSRV, but the published manifest remains compatible with older parsers. #16415 Make CARGO_BIN_EXE_<crate> available at runtime Compatibility Notes Forbid freely casting lifetime bounds of dyn -types Make closure capturing have consistent and correct behaviour around patterns Some finer details of how precise closure captures get affected by pattern matching have been changed. In some cases, this can cause a non-move closure that was previously capturing an entire variable by move, to now capture only part of that variable by move, and other parts by borrow. This can cause the borrow checker to complain where it previously didn't, or cause Drop to run at a different point in time. Standard library macros are now imported via prelude, not via injected #[macro_use] This will raise an error if macros of the same name are glob imported. For example if a crate defines their own matches macro and then glob imports that, it's now ambiguous whether the custom or standard library matches is meant and an explicit import of the name is required to resolve the ambiguity. One exception is core::panic and std::panic , if their import is ambiguous a new warning ( ambiguous_panic_imports ) is raised. This may raise a new warning ( ambiguous_panic_imports ) on #![no_std] code glob importing the std crate. Both core::panic! and std::panic! are then in scope and which is used is ambiguous. Don't strip shebang in expression-context include!(…) s This can cause previously working includes to no longer compile if they included files which started with a shebang. Ambiguous glob reexports are now also visible cross-crate This unifies behavior between local and cross-crate errors on these exports, which may introduce new ambiguity errors. Don't normalize where-clauses before checking well-formedness Introduce a future compatibility warning on codegen attributes on body-free trait methods These attributes currently have no effect in this position. On Windows std::time::SystemTime::checked_sub_duration will return None for times before the Windows epoch (1/1/1601) Lifetime identifiers such as 'a are

Improvements and security content

• 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 LazyCell::get_mut LazyCell::force_mut LazyLock::get LazyLock::get_mut LazyLock::force_mut impl TryFrom<char> for usize std::iter::Peekable::next_if_map std::iter::Peekable::next_if_map_mut x86 avx512fp16 intrinsics (excluding those that depend directly on the unstable f16 type) AArch64 NEON fp16 intrinsics (excluding those that depend directly on the unstable f16 type) f32::consts::EULER_GAMMA f64::consts::EULER_GAMMA f32::consts::GOLDEN_RATIO f64::consts::GOLDEN_RATIO These previously stable APIs are now stable in const contexts: f32::mul_add f64::mul_add Cargo Stabilize the config include key. The top-level include config key allows loading additional config files, enabling better organization, sharing, and management of Cargo configurations across projects and environments. docs #16284 Stabilize the pubtime field in registry index. This records when a crate version was published and enables time-based dependency resolution in the future. Note that crates.io will gradually backfill existing packages when a new version is published. Not all crates have pubtime yet. #16369 #16372 Cargo now parses TOML v1.1 for manifests and configuration files. Note that using these features in Cargo.toml will raise your development MSRV, but the published manifest remains compatible with older parsers. #16415 Make CARGO_BIN_EXE_<crate> available at runtime Compatibility Notes Forbid freely casting lifetime bounds of dyn -types Make closure capturing have consistent and correct behaviour around patterns Some finer details of how precise closure captures get affected by pattern matching have been changed. In some cases, this can cause a non-move closure that was previously capturing an entire variable by move, to now capture only part of that variable by move, and other parts by borrow. This can cause the borrow checker to complain where it previously didn't, or cause Drop to run at a different point in time. Standard library macros are now imported via prelude, not via injected #[macro_use] This will raise an error if macros of the same name are glob imported. For example if a crate defines their own matches macro and then glob imports that, it's now ambiguous whether the custom or standard library matches is meant and an explicit import of the name is required to resolve the ambiguity. One exception is core::panic and std::panic , if their import is ambiguous a new warning ( ambiguous_panic_imports ) is raised. This may raise a new warning ( ambiguous_panic_imports ) on #![no_std] code glob importing the std crate. Both core::panic! and std::panic! are then in scope and which is used is ambiguous. Don't strip shebang in expression-context include!(…) s This can cause previously working includes to no longer compile if they included files which started with a shebang. Ambiguous glob reexports are now also visible cross-crate This unifies behavior between local and cross-crate errors on these exports, which may introduce new ambiguity errors. Don't normalize where-clauses before checking well-formedness Introduce a future compatibility warning on codegen attributes on body-free trait methods These attributes currently have no effect in this position. On Windows std::time::SystemTime::checked_sub_duration will return None for times before the Windows epoch (1/1/1601) Lifetime identifiers such as 'a are

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