Update Debug repr of ObjectLifetimeDefault::Empty

to align with its actual name

Author: fmease

compiler/rustc_passes/src/check_attr.rs

@@ -695,7 +695,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 let hir::GenericParamKind::Type { .. } = p.kind else { continue };
                 let default = tcx.object_lifetime_default(p.def_id);
                 let repr = match default {
-                    ObjectLifetimeDefault::Empty => "BaseDefault".to_owned(),
+                    ObjectLifetimeDefault::Empty => "Empty".to_owned(),
                     ObjectLifetimeDefault::Static => "'static".to_owned(),
                     ObjectLifetimeDefault::Param(def_id) => tcx.item_name(def_id).to_string(),
                     ObjectLifetimeDefault::Ambiguous => "Ambiguous".to_owned(),

tests/ui/object-lifetime/object-lifetime-default.rs

@@ -2,13 +2,13 @@
 
 #[rustc_object_lifetime_default]
 struct A<
-    T, //~ ERROR BaseDefault
+    T, //~ ERROR Empty
 >(T);
 
 #[rustc_object_lifetime_default]
 struct B<
     'a,
-    T, //~ ERROR BaseDefault
+    T, //~ ERROR Empty
 >(&'a (), T);
 
 #[rustc_object_lifetime_default]

tests/ui/object-lifetime/object-lifetime-default.stderr

@@ -1,10 +1,10 @@
-error: BaseDefault
+error: Empty
   --> $DIR/object-lifetime-default.rs:5:5
    |
 LL |     T,
    |     ^
 
-error: BaseDefault
+error: Empty
   --> $DIR/object-lifetime-default.rs:11:5
    |
 LL |     T,