- [Stabilize the `#[diagnostic]` namespace and `#[diagnostic::on_unimplemented]` attribute](https://github.com/rust-lang/rust/pull/119888/)
- [Make async-fn-in-trait implementable with concrete signatures](https://github.com/rust-lang/rust/pull/120103/)
- [Make matching on NaN a hard error, and remove the rest of `illegal_floating_point_literal_pattern`](https://github.com/rust-lang/rust/pull/116284/)
- [static mut: allow mutable reference to arbitrary types, not just slices and arrays](https://github.com/rust-lang/rust/pull/117614/)
- [Extend `invalid_reference_casting` to include references casting to bigger memory layout](https://github.com/rust-lang/rust/pull/118983/)
- [Add `non_contiguous_range_endpoints` lint for singleton gaps after exclusive ranges](https://github.com/rust-lang/rust/pull/118879/)
- [Add `wasm_c_abi` lint for use of older wasm-bindgen versions](https://github.com/rust-lang/rust/pull/117918/)
This lint currently only works when using Cargo.
- [Update `indirect_structural_match` and `pointer_structural_match` lints to match RFC](https://github.com/rust-lang/rust/pull/120423/)
- [Make non-`PartialEq`-typed consts as patterns a hard error](https://github.com/rust-lang/rust/pull/120805/)
- [Split `refining_impl_trait` lint into `_reachable`, `_internal` variants](https://github.com/rust-lang/rust/pull/121720/)
- [Remove unnecessary type inference when using associated types inside of higher ranked `where`-bounds](https://github.com/rust-lang/rust/pull/119849)
- [Weaken eager detection of cyclic types during type inference](https://github.com/rust-lang/rust/pull/119989)
- [`trait Trait: Auto {}`: allow upcasting from `dyn Trait` to `dyn Auto`](https://github.com/rust-lang/rust/pull/119338)
Compiler
--------
- [Made `INVALID_DOC_ATTRIBUTES` lint deny by default](https://github.com/rust-lang/rust/pull/111505/)
- [Increase accuracy of redundant `use` checking](https://github.com/rust-lang/rust/pull/117772/)
- [Suggest moving definition if non-found macro_rules! is defined later](https://github.com/rust-lang/rust/pull/121130/)
- [Lower transmutes from int to pointer type as gep on null](https://github.com/rust-lang/rust/pull/121282/)
Target changes:
- [Windows tier 1 targets now require at least Windows 10](https://github.com/rust-lang/rust/pull/115141/)
- [Enable CMPXCHG16B, SSE3, SAHF/LAHF and 128-bit Atomics in tier 1 Windows](https://github.com/rust-lang/rust/pull/120820/)
- [Stabilize global cache data tracking](https://github.com/rust-lang/cargo/pull/13492/)
Misc
----
- [rustdoc: add `--test-builder-wrapper` arg to support wrappers such as RUSTC_WRAPPER when building doctests](https://github.com/rust-lang/rust/pull/114651/)
Compatibility Notes
-------------------
- [Many unsafe precondition checks now run for user code with debug assertions enabled](https://github.com/rust-lang/rust/pull/120594/)
This change helps users catch undefined behavior in their code, though the details of how much is checked are generally not stable.
- [riscv only supports split_debuginfo=off for now](https://github.com/rust-lang/rust/pull/120518/)
- [Consistently check bounds on hidden types of `impl Trait`](https://github.com/rust-lang/rust/pull/121679)
- [Change equality of higher ranked types to not rely on subtyping](https://github.com/rust-lang/rust/pull/118247)
- [When called, additionally check bounds on normalized function return type](https://github.com/rust-lang/rust/pull/118882)
- [Expand coverage for `arithmetic_overflow` lint](https://github.com/rust-lang/rust/pull/119432/)
- [Fix detection of potential interior mutability in `const` initializers](https://github.com/rust-lang/rust/issues/121250)
This code was accidentally accepted. The fix can break generic code that borrows a value of unknown type,
as there is currently no way to declare "this type has no interior mutability". In the future, stabilizing
the [`Freeze` trait](https://github.com/rust-lang/rust/issues/121675) will allow proper support for such code.