Filter const trait syntax and some unstable trait

The Rust standard library has some unstable trait and const trait syntax

Although rustc_const_unstable can be handle correctly, r-a will output it when completing item-list

I want to implement it, but there are two problems:

1. Which traits need to be removed itself instead of just removing [const]? Unstable and in the std::marker?
2. When will it be disabled this? in configure? #![feature(const_trait_impl)]? Or something else?

struct Foo;
impl Iterator for Foo {
    fol$0
}

Current:

struct Foo;
impl Iterator for Foo {
    fn fold<B, F>(mut self, init: B, mut f: F) -> B
    where
        Self: Sized + [const] std::marker::Destruct,
        F: [const] FnMut(B, Self::Item) -> B + [const] std::marker::Destruct,
    {
        $0
    }
}

Expect:

struct Foo;
impl Iterator for Foo {
    fn fold<B, F>(mut self, init: B, mut f: F) -> B
    where
        Self: Sized,
        F: FnMut(B, Self::Item) -> B,
    {
        $0
    }
}

Reproduce item-list completion for the provided Iterator implementation and inspect how rust-analyzer handles rustc_const_unstable and const trait syntax. Determine which unstable traits and [const] bounds should be omitted, and verify completion produces the expected fold signature without them.