Overflow with use of `Self` in inherent impl on trait

Code: http://is.gd/zUrIKd

pub trait NBTTypeHelper where Self: NBTType {
    type Tagtype = Self;
}

pub trait NBTType {
}

impl NBTTypeHelper for NBTType {
    type Tagtype = <Self as NBTTypeHelper>::Tagtype;
}

fn main() {}

No, I think it is dupe.

I was think it same as #23305
Could someone change the bad title?

[apasel422]

Still an issue.

[jfager]

Still an issue, updated playpen

[steveklabnik]

Triage: still reproduces today

[Spoonbender]

Triage: no change

up-to-date repro:

#![feature(associated_type_defaults)]

pub trait NBTTypeHelper where Self: NBTType {
	type Tagtype = Self;
}

pub trait NBTType {
}

impl NBTTypeHelper for dyn NBTType {
	type Tagtype = <Self as NBTTypeHelper>::Tagtype;
}

fn main() {}