I feel like an implementation like `impl<T, R> RangeBounds<T> for &'_ R where R: RangeBounds<T>`

would be a nice QOL addition. It is trivial to implement because all methods of `RangeBound`

take `&self`

, and it would allow people to write `fn foo(r: &impl RangeBounds<usize>)`

. What do you think?

You can already implement `RangeBounds<_>`

for `&'_ R`

if you own `R`

, so the standard library adding that implementation would be a breaking change.

In more jargony terms, `&`

is fundamental, so that implementation is a blanket implementation.