Auto merge of #117908 - lcnr:region-kind-rename, r=BoxyUwU

finish `RegionKind` renaming

second step of https://github.com/rust-lang/types-team/issues/95

continues the work from #117876. While working on this and I encountered a bunch of further cleanup which I'll either open a tracking issue for or will do in a separate PR:
- rewrite the `RegionKind` docs, they still talk about `ReEmpty` and are generally out of date
- rename `DescriptionCtx` to `DescriptionCtxt`
- what is `CheckRegions::Bound`?
- `collect_late_bound_regions` et al
- `erase_late_bound_regions` -> `instantiate_bound_regions_with_erased`?
- `EraseEarlyRegions` visitor should be removed, feels duplicate

r? `@BoxyUwU`

src/librustdoc/clean/auto_trait.rs

@@ -723,7 +723,7 @@ fn is_fn_trait(&self, path: &Path) -> bool {
 
 fn region_name(region: Region<'_>) -> Option<Symbol> {
     match *region {
-        ty::ReEarlyBound(r) => Some(r.name),
+        ty::ReEarlyParam(r) => Some(r.name),
         _ => None,
     }
 }
@@ -743,7 +743,7 @@ fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
             // These are the regions that can be seen in the AST.
             ty::ReVar(vid) => self.vid_to_region.get(&vid).cloned().unwrap_or(r),
-            ty::ReEarlyBound(_) | ty::ReStatic | ty::ReBound(..) | ty::ReError(_) => r,
+            ty::ReEarlyParam(_) | ty::ReStatic | ty::ReBound(..) | ty::ReError(_) => r,
             r => bug!("unexpected region: {r:?}"),
         }
     }

src/librustdoc/clean/mod.rs

@@ -287,9 +287,9 @@ pub(crate) fn clean_middle_region<'tcx>(region: ty::Region<'tcx>) -> Option<Life
         ty::ReStatic => Some(Lifetime::statik()),
         _ if !region.has_name() => None,
         ty::ReBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => Some(Lifetime(name)),
-        ty::ReEarlyBound(ref data) => Some(Lifetime(data.name)),
+        ty::ReEarlyParam(ref data) => Some(Lifetime(data.name)),
         ty::ReBound(..)
-        | ty::ReFree(..)
+        | ty::ReLateParam(..)
         | ty::ReVar(..)
         | ty::ReError(_)
         | ty::RePlaceholder(..)
@@ -1928,13 +1928,13 @@ fn clean_trait_object_lifetime_bound<'tcx>(
     // latter contrary to `clean_middle_region`.
     match *region {
         ty::ReStatic => Some(Lifetime::statik()),
-        ty::ReEarlyBound(region) if region.name != kw::Empty => Some(Lifetime(region.name)),
+        ty::ReEarlyParam(region) if region.name != kw::Empty => Some(Lifetime(region.name)),
         ty::ReBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) if name != kw::Empty => {
             Some(Lifetime(name))
         }
-        ty::ReEarlyBound(_)
+        ty::ReEarlyParam(_)
         | ty::ReBound(..)
-        | ty::ReFree(_)
+        | ty::ReLateParam(_)
         | ty::ReVar(_)
         | ty::RePlaceholder(_)
         | ty::ReErased

src/tools/clippy/clippy_lints/src/pass_by_ref_or_value.rs

@@ -175,7 +175,7 @@ fn check_poly_fn(&mut self, cx: &LateContext<'tcx>, def_id: LocalDefId, decl: &F
                         },
                         // Early bound regions on functions are either from the containing item, are bounded by another
                         // lifetime, or are used as a bound for a type or lifetime.
-                        RegionKind::ReEarlyBound(..) => continue,
+                        RegionKind::ReEarlyParam(..) => continue,
                         _ => (),
                     }
 

src/tools/clippy/clippy_lints/src/ptr.rs

@@ -465,9 +465,9 @@ fn check_fn_args<'cx, 'tcx: 'cx>(
                                     .walk()
                                     .filter_map(|arg| {
                                         arg.as_region().and_then(|lifetime| match lifetime.kind() {
-                                            ty::ReEarlyBound(r) => Some(r.def_id),
+                                            ty::ReEarlyParam(r) => Some(r.def_id),
                                             ty::ReBound(_, r) => r.kind.get_id(),
-                                            ty::ReFree(r) => r.bound_region.get_id(),
+                                            ty::ReLateParam(r) => r.bound_region.get_id(),
                                             ty::ReStatic
                                             | ty::ReVar(_)
                                             | ty::RePlaceholder(_)