[PATCH 05/33] rust: remove `RUSTC_HAS_COERCE_POINTEE` and simplify code

[Gary Guo]

On Wed Apr 1, 2026 at 12:45 PM BST, Miguel Ojeda wrote:
> With the Rust version bump in place, the `RUSTC_HAS_COERCE_POINTEE`
> Kconfig (automatic) option is always true.
> 
> Thus remove the option and simplify the code.
> 
> In particular, this includes removing our use of the predecessor unstable
> features we used with Rust < 1.84.0 (`coerce_unsized`, `dispatch_from_dyn`
> and `unsize`).
> 
> Signed-off-by: Miguel Ojeda <ojeda at kernel.org>

Reviewed-by: Gary Guo <gary at garyguo.net>

> ---
>  init/Kconfig              |  3 ---
>  rust/kernel/alloc/kbox.rs | 29 ++---------------------------
>  rust/kernel/lib.rs        |  8 +-------
>  rust/kernel/list/arc.rs   | 22 +---------------------
>  rust/kernel/sync/arc.rs   | 21 ++-------------------
>  5 files changed, 6 insertions(+), 77 deletions(-)