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 compatiblity 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.
• Improve spacing between printed tokens.
• Merge the unused_tuple_struct_fields lint into dead_code.
• Error on incorrect implied bounds in well-formedness check, with a temporary exception for Bevy.
• Fix coverage instrumentation/reports for non-ASCII source code.
• Fix fn/const items implied bounds and well-formedness check.
• Promote riscv32{im|imafc}-unknown-none-elf targets to tier 2.
• Add several new tier 3 targets:
  • aarch64-unknown-illumos
  • hexagon-unknown-none-elf
  • riscv32imafc-esp-espidf
  • riscv32im-risc0-zkvm-elf

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

Libraries

• Implement From<&[T; N]> for Cow<[T]>.
• Remove special-case handling of vec.split_off(0).

Stabilized APIs

• array::each_ref
• array::each_mut
• core::net
• f32::round_ties_even
• f64::round_ties_even
• mem::offset_of!
• slice::first_chunk
• slice::first_chunk_mut
• slice::split_first_chunk
• slice::split_first_chunk_mut
• slice::last_chunk
• slice::last_chunk_mut
• slice::split_last_chunk
• slice::split_last_chunk_mut
• slice::chunk_by
• slice::chunk_by_mut
• Bound::map
• File::create_new
• Mutex::clear_poison
• RwLock::clear_poison

Cargo

• Extend the build directive syntax with cargo::.
• Stabilize metadata id format as PackageIDSpec.
• Pull out cargo-util-schemas as a crate.
• Strip all debuginfo when debuginfo is not requested.
• Inherit jobserver from env for all kinds of runners.
• Deprecate rustc plugin support in cargo.

Rustdoc

• Allows links in markdown headings.
• Search for tuples and unit by type with ().
• Clean up the source sidebar's hide button.
• Prevent JS injection from localStorage.

Misc

• Recommend version-sorting for all sorting in style guide.

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.

• Add more weirdness to weird-exprs.rs.