Remove impl const and ~const in the standard library

Otherwise it will fail to compile on nightly-2023-04-19

See rust-lang/rust#110395

Author: equation314

crates/axerrno/src/lib.rs

@@ -10,7 +10,6 @@
 //! [`std::io::ErrorKind`]: https://doc.rust-lang.org/std/io/enum.ErrorKind.html
 
 #![no_std]
-#![feature(const_trait_impl)]
 
 mod linux_errno {
     include!(concat!(env!("OUT_DIR"), "/linux_errno.rs"));
@@ -167,7 +166,7 @@ impl AxError {
     }
 }
 
-impl const From<AxError> for LinuxError {
+impl From<AxError> for LinuxError {
     fn from(e: AxError) -> Self {
         use AxError::*;
         match e {

crates/capability/src/lib.rs

@@ -27,7 +27,6 @@
 //!
 
 #![no_std]
-#![feature(const_trait_impl)]
 
 bitflags::bitflags! {
     /// Capabilities (access rights).
@@ -132,7 +131,8 @@ impl<T> WithCap<T> {
     }
 }
 
-impl const From<CapError> for axerrno::AxError {
+impl From<CapError> for axerrno::AxError {
+    #[inline]
     fn from(_: CapError) -> Self {
         Self::PermissionDenied
     }

crates/driver_block/src/lib.rs

@@ -2,6 +2,7 @@
 
 #![no_std]
 #![feature(doc_auto_cfg)]
+#![feature(const_trait_impl)]
 
 #[cfg(feature = "ramdisk")]
 pub mod ramdisk;

crates/driver_block/src/ramdisk.rs

@@ -44,7 +44,7 @@ impl RamDisk {
     }
 }
 
-impl BaseDriverOps for RamDisk {
+impl const BaseDriverOps for RamDisk {
     fn device_type(&self) -> DeviceType {
         DeviceType::Block
     }

crates/linked_list/src/lib.rs

@@ -5,7 +5,6 @@
 //! [1]: https://github.com/Rust-for-Linux/linux/blob/rust/rust/kernel/linked_list.rs
 
 #![no_std]
-#![feature(const_trait_impl)]
 
 mod linked_list;
 

crates/linked_list/src/linked_list.rs

@@ -207,7 +207,7 @@ impl<G: AdapterWrapped> List<G> {
     }
 }
 
-impl<G: AdapterWrapped> const Default for List<G> {
+impl<G: AdapterWrapped> Default for List<G> {
     fn default() -> Self {
         Self::new()
     }