Incorrectly modifies associated type in macro body

[programmerjake]

https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=4d7f756328bf278741b41d51f006cf8a

Formatting:

macro_rules! m {
    () => {
        type Type;
    };
}

Incorrectly produces:

macro_rules! m {
    () => {
        type Type = impl ;
    };
}

m! is intended to be used like so:

pub trait Trait {
    m! {}
}