⚙️ This is an internal compiler API. (rustc_private)
This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.
Uses a sorted slice data: &[E] as a kind of "multi-map". The
key_fn extracts a key of type K from the data, and this
function finds the range of elements that match the key. data
must have been sorted as if by a call to sort_by_key for this to