refactor: remove #![feature(const_fn_trait_bound)]

The `const_fn_trait_bound` feature was stabilized by
<rust-lang/rust#93827>.

README.md

@@ -47,7 +47,6 @@ The R3 original kernel is provided as a separate package [`r3_kernel`][].
 
 ```rust
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

doc/toolchain_limitations.md

@@ -168,7 +168,6 @@ fn clone_projection<T: Trait>(p: &T::Proj) -> T::Proj {
 ```
 
 ```rust,compile_fail,E0277
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 
 trait Trait {
@@ -201,7 +200,6 @@ trait Trait: ~const Clone {}
 ### `[tag:impl_block_const_bounds]` The trait bounds of an `impl` block can't include `~const`
 
 ```rust,compile_fail
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 struct Cfg<C>(C);
 trait CfgBase {}
@@ -214,7 +212,6 @@ impl<C: ~const CfgBase> Cfg<C> {
 A work-around is to move the trait bounds to the `const fn`s inside.
 
 ```rust
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 struct Cfg<C>(C);
 trait CfgBase {}
@@ -232,7 +229,6 @@ impl<C> Cfg<C> {
 The following code doesn't compile (which is okay) because `T` might not be `T: const Drop`.
 
 ```rust,compile_fail,E0493
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]
 #![feature(const_option)]
@@ -248,7 +244,6 @@ impl<T> const Drop for Type<T> {
 The obvious solution is to add `T: ~const Drop` to the `Drop` implementation as well as to the type definition. However, this doesn't work because `~const` is not allowed to appear in the type definition.
 
 ```rust,compile_fail,E0367
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]
 #![feature(const_option)]
@@ -266,7 +261,6 @@ impl<T: ~const Drop> const Drop for Type<T> {
 According to [rust-lang/rust#93028](https://github.com/rust-lang/rust/pull/93028), we can actually remove `~const` from this type definition, and the compiler permits the `Drop` implementation to have an extra `~const`. Unfortunately, this leaves a `Drop` trait bound on the type, which actually cover different types than `~const Drop` does. That's because `T: ~const Drop` means that `T` can be dropped in a constant context (n.b. this is [a special case for `Drop`](https://internals.rust-lang.org/t/pre-rfc-revamped-const-trait-impl-aka-rfc-2632/15192#const-drop-in-generic-code-6) and doesn't apply to other traits), while `T: Drop` means that `T` has a user-defined `Drop` implementation.
 
 ```rust,compile_fail,E0277
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]
 #![feature(const_option)]
@@ -283,7 +277,6 @@ let _ = Type(Some(()));
 A work-around is to enclose `T` in a container that unconditionally implements `const Drop`.
 
 ```rust
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]
 #![feature(const_option)]
@@ -308,7 +301,6 @@ const _: () = { let _ = Type(Some(())); };
 ### `[tag:const_closures]` Closures can't be `impl const Fn`
 
 ```rust
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 const fn identity<C: ~const Fn()>(x: C) -> C { x }
 const fn foo() {}
@@ -317,7 +309,6 @@ identity(|| {});
 ```
 
 ```rust,compile_fail,E0277
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 const fn identity<C: ~const Fn()>(x: C) -> C { x }
 // error[E0277]: the trait bound `[[email protected]:6:26: 6:31]: ~const Fn<()>` is not satisfied

examples/basic/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]

examples/basic_gr_peach/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]

examples/basic_nucleo_f401re/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

examples/basic_rp_pico/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

examples/basic_wio_terminal/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

examples/smp_rp_pico/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

src/r3/src/lib.rs

@@ -3,7 +3,6 @@
 #![feature(const_precise_live_drops)]
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(type_alias_impl_trait)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_impl_trait)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]

src/r3/src/tests.rs

@@ -9,7 +9,6 @@ pub(crate) macro doc_test(
 ) {concat!(
 ignore_if_port_std_does_not_support_target!($head), "\n ",
 "#   #![feature(const_fn_fn_ptr_basics)]
- #   #![feature(const_fn_trait_bound)]
  #   #![feature(const_refs_to_cell)]
  #   #![feature(const_impl_trait)]
  #   #![feature(const_trait_impl)]

src/r3_core/src/bind.rs

@@ -693,7 +693,6 @@ impl<'pool, System, T> DivideBind<'pool, System, T> {
 ///
 /// ```rust
 /// #![feature(const_fn_fn_ptr_basics)]
-/// #![feature(const_fn_trait_bound)]
 /// #![feature(const_trait_impl)]
 /// #![feature(const_mut_refs)]
 /// use r3_core::{bind::Bind, kernel::{Cfg, traits}, prelude::*};
@@ -823,7 +822,6 @@ impl<'pool, const LEN: usize, System, T> const UnzipBind for Bind<'pool, System,
 ///
 /// ```rust
 /// #![feature(const_fn_fn_ptr_basics)]
-/// #![feature(const_fn_trait_bound)]
 /// #![feature(const_trait_impl)]
 /// #![feature(const_mut_refs)]
 /// use r3_core::{
@@ -1300,7 +1298,6 @@ where
 /// # Example
 ///
 /// ```rust
-/// #![feature(const_fn_trait_bound)]
 /// #![feature(const_trait_impl)]
 /// #![feature(const_mut_refs)]
 /// use core::cell::UnsafeCell;

src/r3_core/src/kernel/mutex.rs

@@ -41,7 +41,6 @@ define_object! {
 /// # Examples
 ///
 /// ```rust
-/// #![feature(const_fn_trait_bound)]
 /// #![feature(const_trait_impl)]
 /// #![feature(const_mut_refs)]
 /// use r3_core::kernel::{

src/r3_core/src/kernel/timer.rs

@@ -273,7 +273,6 @@ define_object! {
 ///
 /// ```rust
 /// # #![feature(const_fn_fn_ptr_basics)]
-/// # #![feature(const_fn_trait_bound)]
 /// # #![feature(const_trait_impl)]
 /// # #![feature(const_mut_refs)]
 /// use r3_core::{kernel::{Cfg, StaticTimer, traits}, time::Duration};
@@ -315,7 +314,6 @@ define_object! {
 ///
 /// ```rust
 /// # #![feature(const_fn_fn_ptr_basics)]
-/// # #![feature(const_fn_trait_bound)]
 /// # #![feature(const_trait_impl)]
 /// # #![feature(const_mut_refs)]
 /// use r3_core::{kernel::{Cfg, StaticTimer, traits, prelude::*}, time::Duration};

src/r3_core/src/lib.md

@@ -104,7 +104,6 @@ Configuration functions are highly composable as they can make nested calls to o
 
 ```rust
 # #![feature(const_fn_fn_ptr_basics)]
-# #![feature(const_fn_trait_bound)]
 # #![feature(const_trait_impl)]
 # #![feature(const_mut_refs)]
 # use r3_core::kernel::{Cfg, traits};

src/r3_core/src/lib.rs

@@ -16,7 +16,6 @@
 #![feature(const_cell_into_inner)]
 #![feature(const_ptr_offset_from)]
 #![feature(type_alias_impl_trait)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_intrinsic_copy)]
 #![feature(const_slice_ptr_len)]
 #![feature(exhaustive_patterns)] // `let Ok(()) = Ok::<(), !>(())`

src/r3_kernel/src/lib.rs

@@ -5,7 +5,6 @@
 #![feature(const_raw_ptr_comparison)]
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(cfg_target_has_atomic)] // `#[cfg(target_has_atomic_load_store)]`
-#![feature(const_fn_trait_bound)]
 #![feature(const_intrinsic_copy)]
 #![feature(exhaustive_patterns)] // `let Ok(()) = Ok::<(), !>(())`
 #![feature(generic_const_exprs)]

src/r3_port_arm/src/lib.rs

@@ -1,6 +1,5 @@
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(const_ptr_offset_from)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_ptr_offset)]
 #![feature(const_trait_impl)]

src/r3_port_arm_m/src/lib.rs

@@ -1,6 +1,5 @@
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(const_ptr_offset_from)]
-#![feature(const_fn_trait_bound)]
 #![feature(generic_const_exprs)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]

src/r3_port_arm_m_test_driver/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

src/r3_port_arm_test_driver/src/main.rs

@@ -4,7 +4,6 @@
 //! title="Screwdriver"></a></div>
 #![doc = include_str!("./common.md")]
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

src/r3_port_riscv/src/lib.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(generic_const_exprs)]
 #![feature(const_trait_impl)]
 #![feature(naked_functions)]

src/r3_port_riscv_test_driver/src/main.rs

@@ -1,5 +1,4 @@
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(const_ptr_offset)]

src/r3_port_std/benches/test_suite.rs

@@ -1,5 +1,4 @@
 //! Runs test cases defined in `r3_test_suite`.
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_mut_refs)]
 #![feature(slice_ptr_len)]

src/r3_port_std/src/lib.md

@@ -4,7 +4,6 @@ The port for running [`::r3_kernel`][] in a hosted environment
 
 ```rust
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]

src/r3_port_std/src/lib.rs

@@ -1,5 +1,4 @@
 #![feature(cfg_target_has_atomic)] // `#[cfg(target_has_atomic_load_store)]`
-#![feature(const_fn_trait_bound)]
 #![feature(atomic_mut_ptr)]
 #![feature(thread_local)]
 #![feature(deadline_api)]

src/r3_port_std/tests/test_suite.rs

@@ -1,6 +1,5 @@
 //! Runs test cases defined in `r3_test_suite`.
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]

src/r3_portkit/src/lib.rs

@@ -1,6 +1,5 @@
 //! R3 PortKit
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(generic_const_exprs)]
 #![feature(adt_const_params)]
 #![feature(naked_functions)]

src/r3_support_rp2040/src/lib.rs

@@ -4,7 +4,6 @@
 //! [R3]: ::r3
 //! [Raspberry Pi Pico]: https://pico.raspberrypi.org
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(exhaustive_patterns)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]

src/r3_support_rza1/src/lib.rs

@@ -5,7 +5,6 @@
 //! [RZ/A1H]: https://www.renesas.com/us/en/products/microcontrollers-microprocessors/rz/rza/rza1h.html
 //! [GR-PEACH]: https://www.renesas.com/us/en/products/gadget-renesas/boards/gr-peach.html
 #![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]
 #![cfg_attr(

src/r3_test_suite/src/lib.rs

@@ -2,7 +2,6 @@
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(cfg_target_has_atomic)]
 #![feature(const_transmute_copy)]
-#![feature(const_fn_trait_bound)]
 #![feature(const_refs_to_cell)]
 #![feature(const_trait_impl)]
 #![feature(const_mut_refs)]