Short impl's wrap leaving "where" dangling on a line by itself

[SamWhited]

Consider the following formatting (from the current nightly build as of 2017-06-17) for a generic Set trait:

impl<T> Set<T> for T
where
    T: PartialEq,
{
    default fn contains(&self, c: T) -> bool {
        *self == c
    }
}

This feels unnecessary to me. When it's this short, and could always fit on a line, there's no reason to wrap:

impl<T> Set<T> for T where T: PartialEq,

If we always want to wrap for consistency with longer types, it feels poor to leave the "where" on a line all by itself, the following would look better (and extra generic parameters could still be added underneath and tabbed out to line up with the first one):

impl<T> Set<T> for T
    where T: PartialEq,

[sgrif]

This was pretty exhaustively discussed in the RFC: rust-lang/style-team#38

You can always write impl<T: PartialEq> Set<T> instead

[SamWhited]

Thanks; it's hard to find any formatting / code things with GitHub's search. If this is intended then there's no issue. For a simple case like this at least it is suprising and "looks like" a bug to me, but of course, maybe it's just me.

You can always write impl<T: PartialEq> Set instead

I assume where exists for a reason and this would not be practical in all cases, however, in this deliberately minimal example you're right, I could.

[nrc]

and here rust-lang/style-team#74 too (closing because it is an RFC issue, not a Rustfmt one)