make uninitialized_error_reported a set of locals

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -100,12 +100,12 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             move_site_vec.iter().map(|move_site| move_site.moi).collect();
 
         if move_out_indices.is_empty() {
-            let root_place = PlaceRef { projection: &[], ..used_place };
+            let root_local = used_place.local;
 
-            if !self.uninitialized_error_reported.insert(root_place) {
+            if !self.uninitialized_error_reported.insert(root_local) {
                 debug!(
                     "report_use_of_moved_or_uninitialized place: error about {:?} suppressed",
-                    root_place
+                    root_local
                 );
                 return;
             }

compiler/rustc_borrowck/src/lib.rs

@@ -566,7 +566,7 @@ struct MirBorrowckCtxt<'cx, 'tcx> {
     fn_self_span_reported: FxIndexSet<Span>,
     /// This field keeps track of errors reported in the checking of uninitialized variables,
     /// so that we don't report seemingly duplicate errors.
-    uninitialized_error_reported: FxIndexSet<PlaceRef<'tcx>>,
+    uninitialized_error_reported: FxIndexSet<Local>,
     /// This field keeps track of all the local variables that are declared mut and are mutated.
     /// Used for the warning issued by an unused mutable local variable.
     used_mut: FxIndexSet<Local>,