The headline ergonomic win is the core::range overhaul. Range, RangeFrom, and RangeInclusive now implement IntoIterator rather than Iterator, which makes them Copy. You can stash a slice accessor in a Copy struct without splitting it into separate start and end fields. The release also stabilizes assert_matches! and debug_assert_matches!, which check a value against a pattern and panic with its Debug output when it doesn't match. New From impls round things out: AssertUnwindSafe, LazyCell, and LazyLock all gain conversions. The one thing to read before you upgrade is the WebAssembly change. The linker no longer passes --allow-undefined, so undefined symbols are now a hard link error instead of being quietly turned into wasm imports. If your wasm build leaned on that implicit behavior, it will break here. Two Cargo CVEs (CVE-2026-5223 and CVE-2026-5222) are patched as well, though crates.io users were never exposed.