Remove some unnecessary rustc_allow_const_fn_unstable attributes.

library/alloc/src/raw_vec.rs

@@ -118,7 +118,6 @@ impl<T, A: Allocator> RawVec<T, A> {
 
     /// Like `new`, but parameterized over the choice of allocator for
     /// the returned `RawVec`.
-    #[rustc_allow_const_fn_unstable(const_fn)]
     pub const fn new_in(alloc: A) -> Self {
         // `cap: 0` means "unallocated". zero-sized types are ignored.
         Self { ptr: Unique::dangling(), cap: 0, alloc }

library/core/src/num/nonzero.rs

@@ -52,7 +52,6 @@ impl $Ty {
                 #[$const_new_unchecked_stability]
                 #[must_use]
                 #[inline]
-                #[rustc_allow_const_fn_unstable(const_fn_fn_ptr_basics)] // required by assert_unsafe_precondition
                 pub const unsafe fn new_unchecked(n: $Int) -> Self {
                     // SAFETY: this is guaranteed to be safe by the caller.
                     unsafe {

library/core/src/option.rs

@@ -1486,7 +1486,6 @@ pub const fn get_or_insert_default(&mut self) -> &mut T
     where
         T: ~const Default,
     {
-        #[rustc_allow_const_fn_unstable(const_fn_trait_bound)]
         const fn default<T: ~const Default>() -> T {
             T::default()
         }

library/core/src/task/wake.rs

@@ -147,7 +147,6 @@ impl RawWakerVTable {
     #[rustc_promotable]
     #[stable(feature = "futures_api", since = "1.36.0")]
     #[rustc_const_stable(feature = "futures_api", since = "1.36.0")]
-    #[rustc_allow_const_fn_unstable(const_fn_fn_ptr_basics)]
     pub const fn new(
         clone: unsafe fn(*const ()) -> RawWaker,
         wake: unsafe fn(*const ()),

library/proc_macro/src/bridge/client.rs

@@ -416,7 +416,6 @@ fn run_client<A: for<'a, 's> DecodeMut<'a, 's, ()>, R: Encode<()>>(
 }
 
 impl Client<fn(crate::TokenStream) -> crate::TokenStream> {
-    #[rustc_allow_const_fn_unstable(const_fn)]
     pub const fn expand1(f: fn(crate::TokenStream) -> crate::TokenStream) -> Self {
         extern "C" fn run(
             bridge: Bridge<'_>,
@@ -429,7 +428,6 @@ extern "C" fn run(
 }
 
 impl Client<fn(crate::TokenStream, crate::TokenStream) -> crate::TokenStream> {
-    #[rustc_allow_const_fn_unstable(const_fn)]
     pub const fn expand2(
         f: fn(crate::TokenStream, crate::TokenStream) -> crate::TokenStream,
     ) -> Self {
@@ -474,7 +472,6 @@ pub fn name(&self) -> &'static str {
         }
     }
 
-    #[rustc_allow_const_fn_unstable(const_fn)]
     pub const fn custom_derive(
         trait_name: &'static str,
         attributes: &'static [&'static str],
@@ -483,7 +480,6 @@ pub const fn custom_derive(
         ProcMacro::CustomDerive { trait_name, attributes, client: Client::expand1(expand) }
     }
 
-    #[rustc_allow_const_fn_unstable(const_fn)]
     pub const fn attr(
         name: &'static str,
         expand: fn(crate::TokenStream, crate::TokenStream) -> crate::TokenStream,
@@ -491,7 +487,6 @@ pub const fn attr(
         ProcMacro::Attr { name, client: Client::expand2(expand) }
     }
 
-    #[rustc_allow_const_fn_unstable(const_fn)]
     pub const fn bang(
         name: &'static str,
         expand: fn(crate::TokenStream) -> crate::TokenStream,

library/proc_macro/src/bridge/scoped_cell.rs

@@ -35,7 +35,6 @@ fn deref_mut(&mut self) -> &mut Self::Target {
 pub struct ScopedCell<T: LambdaL>(Cell<<T as ApplyL<'static>>::Out>);
 
 impl<T: LambdaL> ScopedCell<T> {
-    #[rustc_allow_const_fn_unstable(const_fn)]
     pub const fn new(value: <T as ApplyL<'static>>::Out) -> Self {
         ScopedCell(Cell::new(value))
     }