29b51cdff3
All the slice interners have a wrapper that handles the empty slice case. We can instead handle this in the `slice_interners!` macro, avoiding the need for most of the wrappers, and allowing the interner functions to be renamed from `_intern_foos` to `intern_foos`. The two exceptions: - intern_predicates: I kept this wrapper because there's a FIXME comment about a possible future change. - intern_poly_existential_predicates: I kept this wrapper because it asserts that the slice is empty and sorted.
For more information about how rustc works, see the rustc dev guide.