Const generic param disappears after rustfmt

[n3d-qmp]

I tried this code:

#![feature(generic_const_items)]
trait Trait {
    const N: isize;
}

const C<T: Trait>: isize = T::N;

After rustfmt generic param disappears:

#![feature(generic_const_items)]
trait Trait {
    const N: isize;
}

const C: isize = T::N;

Meta

rustc --version --verbose:
Tested on playground

[n3d-qmp]

@rustbot label +requires-nightly +A-rustfmt +A-const-generics

[fmease]

In the future, please report rustfmt-specific issues over at rust-lang/rustfmt.

Duplicate of rust-lang/rustfmt#5995.