Fix signature to work with example error

Author: Mark-Simulacrum

posts/2022-08-11-Rust-1.63.0.md

@@ -106,8 +106,8 @@ on Linux.
 
 ### Turbofish for generics in functions with `impl Trait`
 
-For a function signature like `fn foo<T>(value: T, f: impl FnOnce())`, it was an
-error to specify the concrete type of `T` via turbofish: `foo::<u32>(3, || {})`
+For a function signature like `fn foo<T>(value: T, f: impl Copy)`, it was an
+error to specify the concrete type of `T` via turbofish: `foo::<u32>(3, 3)`
 would fail with:
 
 ```text