Rust Release Notes

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Language

• Add allow-by-default raw_borrows_via_references lint that checks for references that decay immediately into raw borrows
• Extend unconditional_panic lint 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_literals lint with repeated negation. For instance, it will now no longer lint on --128_i8, which is already detected by the arithmetic_overflow lint. …

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Language

• Allow shortening lifetime of &mut when unsize-coercing, even in an invariant position. For example, you can now coerce a Cell<&'long mut i32> to a Cell<&'short mut dyn Send>. Such shortenings were already previously allowed when coercing a &mut to a &, or coercing a & to a &.
• Add deny-by-default invalid_runtime_symbol_definitions lint and warn-by-default suspicious_runtime_symbol_definitions lint
  • The lints currently specifically targets core runtime symbols like memcmp, memset, strlen, ... and is planned to be expanded in the next few releases.
• Add warn-by-default c_void_returns lint to check core::ffi::c_void as a return type

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Platform Support

• Add powerpc64-unknown-linux-gnuelfv2 as Tier 3
• Add aarch64-unknown-linux-pauthtest as Tier 3 target
• Promote thumbv7a-none-eabi to Tier 2
• Promote thumbv7a-none-eabihf to Tier 2
• Promote thumbv7r-none-eabi to Tier 2
• Promote thumbv7r-none-eabihf to Tier 2 …

<a id="1.97.0-Language"></a>

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

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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.

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Stabilized APIs

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