Rename Rptr to Ref in AST and HIR

The name makes a lot more sense, and `ty::TyKind` calls it `Ref` already
as well.

compiler/rustc_resolve/src/late.rs

@@ -648,7 +648,7 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
         let prev = self.diagnostic_metadata.current_trait_object;
         let prev_ty = self.diagnostic_metadata.current_type_path;
         match ty.kind {
-            TyKind::Rptr(None, _) => {
+            TyKind::Ref(None, _) => {
                 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
                 // NodeId `ty.id`.
                 // This span will be used in case of elision failure.
@@ -2001,7 +2001,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
         impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
             fn visit_ty(&mut self, ty: &'a Ty) {
                 trace!("SelfVisitor considering ty={:?}", ty);
-                if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
+                if let TyKind::Ref(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
                     let lt_id = if let Some(lt) = lt {
                         lt.id
                     } else {