Rust 1.84.0 released

Version
1.84.0 of the Rust language has been released. Changes include
improved version selection for dependencies in Cargo, the beginning of the
migration to a new trait solver, and some updated pointer-provenance APIs.

Most of the time, programmers do not need to worry much about
provenance, and it is very clear how a pointer got
derived. However, when casting pointers to integers and back, the
provenance of the resulting pointer is underspecified. With this
release, Rust is adding a set of APIs that can in many cases
replace the use of integer-pointer-casts, and therefore avoid the
ambiguities inherent to such casts. In particular, the pattern of
using the lowest bits of an aligned pointer to store extra
information can now be implemented without ever casting a pointer
to an integer or back. This makes the code easier to reason about,
easier to analyze for the compiler, and also benefits tools like
Miri and architectures like CHERI that aim to detect and diagnose
pointer misuse.