rust: alloc: remove the borrow module (ToOwned, Cow)

The `Cow` type [1] requires that its generic parameter type implements
the `ToOwned` trait [2], which provides a method to create owned data
from borrowed data, usually by cloning.

However, it is infallible, and thus in most cases it is not useful for
the kernel. [3]

Therefore, introduce `cfg(no_borrow)` to remove the `borrow` module
(which contains `ToOwned` and `Cow`) from `alloc`.

Link: https://doc.rust-lang.org/alloc/borrow/enum.Cow.html [1]
Link: https://doc.rust-lang.org/alloc/borrow/trait.ToOwned.html [2]
Link: https://lore.kernel.org/rust-for-linux/20221204103153.117675b1@GaryWorkstation/ [3]
Cc: Gary Guo <gary@garyguo.net>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Finn Behrens <fin@nyantec.com>
This commit is contained in:
Miguel Ojeda 2022-12-06 02:05:19 +01:00
parent 5dc4c995db
commit 8909a80e3f
4 changed files with 6 additions and 499 deletions

View file

@ -100,7 +100,7 @@
#![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]
#![feature(const_box)]
#![cfg_attr(not(no_global_oom_handling), feature(const_btree_new))]
#![feature(const_cow_is_borrowed)]
#![cfg_attr(not(no_borrow), feature(const_cow_is_borrowed))]
#![feature(const_convert)]
#![feature(const_size_of_val)]
#![feature(const_align_of_val)]
@ -215,6 +215,7 @@ pub mod boxed;
mod boxed {
pub use std::boxed::Box;
}
#[cfg(not(no_borrow))]
pub mod borrow;
pub mod collections;
#[cfg(not(no_global_oom_handling))]