refactor(kernel): start using unwrap_unchecked

The `unwrap_unchecked` methods were recently added to the standard
library [1] and are yet to be stabilized.

[1]: rust-lang/rust#80876

Author: yvt

src/r3/src/kernel/task/readyqueue.rs

@@ -9,7 +9,6 @@ use crate::{
     },
     utils::{
         intrusive_list::{Ident, ListAccessorCell, Static, StaticLink, StaticListHead},
-        unwrap::UnwrapUnchecked,
         Init, PrioBitmap,
     },
 };

src/r3/src/kernel/wait.rs

@@ -10,7 +10,6 @@ use super::{
 
 use crate::utils::{
     intrusive_list::{self, HandleInconsistencyUnchecked, ListAccessorCell},
-    unwrap::UnwrapUnchecked,
     Init,
 };
 

src/r3/src/lib.rs

@@ -16,6 +16,7 @@
 #![feature(set_ptr_value)] // `<*const T>::set_ptr_value`
 #![feature(raw_ref_macros)]
 #![feature(or_patterns)]
+#![feature(option_result_unwrap_unchecked)] // `Option<T>::unwrap_unchecked`
 #![feature(cfg_target_has_atomic)] // `#[cfg(target_has_atomic_load_store)]`
 #![feature(unsafe_block_in_unsafe_fn)] // `unsafe fn` doesn't imply `unsafe {}`
 #![feature(never_type)] // `!`

src/r3/src/utils.rs

@@ -29,7 +29,6 @@ pub mod mem;
 pub(crate) mod pin;
 mod prio_bitmap;
 mod rawcell;
-pub(crate) mod unwrap;
 #[macro_use]
 mod vec;
 #[macro_use]