add missing impl

Author: Kivooeo

library/core/src/ops/function.rs

@@ -310,4 +310,15 @@ mod impls {
  (*self).call_mut(args)
  }
  }
+
+ #[stable(feature = "rust1", since = "1.0.0")]
+ #[rustc_const_unstable(feature = "const_trait_impl", issue = "143874")]
+ impl<A: Tuple, F: ?Sized> const Fn<A> for &mut F
+ where
+ F: [const] Fn<A>,
+ {
+ extern "rust-call" fn call(&self, args: A) -> F::Output {
+ (**self).call(args)
+ }
+ }
 }

tests/ui/const-generics/adt_const_params/non_valtreeable_const_arg-2.stderr

@@ -29,6 +29,8 @@ LL | Wrapper::<function>::call;
  = note: the following trait bounds were not satisfied:
  `Wrapper<function>: Fn<_>`
  which is required by `&Wrapper<function>: Fn<_>`
+ `Wrapper<function>: Fn<_>`
+ which is required by `&mut Wrapper<function>: Fn<_>`
 note: the trait `Fn` must be implemented
  --> $SRC_DIR/core/src/ops/function.rs:LL:COL
  = help: items from traits can only be used if the trait is implemented and in scope

tests/ui/impl-trait/where-allowed.stderr

@@ -385,6 +385,8 @@ LL | fn in_impl_Fn_return_in_return() -> &'static impl Fn() -> impl Debug { pani
  = note: multiple `impl`s satisfying `_: Fn()` found in the following crates: `alloc`, `core`:
  - impl<A, F> Fn<A> for &F
  where A: Tuple, F: Fn<A>, F: ?Sized;
+ - impl<A, F> Fn<A> for &mut F
+ where A: Tuple, F: Fn<A>, F: ?Sized;
  - impl<Args, F, A> Fn<Args> for Box<F, A>
  where Args: Tuple, F: Fn<Args>, A: Allocator, F: ?Sized;
  - impl<F, Args> Fn<Args> for Exclusive<F>

tests/ui/traits/next-solver/well-formed-in-relate.stderr

@@ -10,6 +10,8 @@ LL | x = unconstrained_map();
  = note: multiple `impl`s satisfying `_: Fn()` found in the following crates: `alloc`, `core`:
  - impl<A, F> Fn<A> for &F
  where A: Tuple, F: Fn<A>, F: ?Sized;
+ - impl<A, F> Fn<A> for &mut F
+ where A: Tuple, F: Fn<A>, F: ?Sized;
  - impl<Args, F, A> Fn<Args> for Box<F, A>
  where Args: Tuple, F: Fn<Args>, A: Allocator, F: ?Sized;
  - impl<F, Args> Fn<Args> for Exclusive<F>