Use new Place::base_direct API when possible

Its functionality is duplicated in `borrowed_locals.rs` and
`path_utils.rs`

src/librustc_mir/borrow_check/path_utils.rs

@@ -2,8 +2,7 @@ use crate::borrow_check::borrow_set::{BorrowSet, BorrowData, TwoPhaseActivation}
 use crate::borrow_check::places_conflict;
 use crate::borrow_check::AccessDepth;
 use crate::dataflow::indexes::BorrowIndex;
-use rustc::mir::{BasicBlock, Location, Body, Place, PlaceBase};
-use rustc::mir::{ProjectionElem, BorrowKind};
+use rustc::mir::{BasicBlock, BorrowKind, Location, Body, Place, PlaceBase};
 use rustc::ty::{self, TyCtxt};
 use rustc_data_structures::graph::dominators::Dominators;
 
@@ -132,21 +131,8 @@ pub(super) fn is_active<'tcx>(
 
 /// Determines if a given borrow is borrowing local data
 /// This is called for all Yield statements on movable generators
-pub(super) fn borrow_of_local_data(place: &Place<'_>) -> bool {
-    place.iterate(|place_base, place_projection| {
-        match place_base {
-            PlaceBase::Static(..) => return false,
-            PlaceBase::Local(..) => {},
-        }
-
-        for proj in place_projection {
-            // Reborrow of already borrowed data is ignored
-            // Any errors will be caught on the initial borrow
-            if proj.elem == ProjectionElem::Deref {
-                return false;
-            }
-        }
-
-        true
-    })
+pub(super) fn borrow_of_local_data<'tcx>(place: &Place<'tcx>) -> bool {
+    place.base_direct()
+        .and_then(PlaceBase::local)
+        .is_some()
 }

src/librustc_mir/dataflow/impls/borrowed_locals.rs

@@ -64,7 +64,7 @@ impl<'a, 'tcx> BitDenotation<'tcx> for HaveBeenBorrowedLocals<'a, 'tcx> {
             // Drop terminators borrows the location
             TerminatorKind::Drop { location, .. } |
             TerminatorKind::DropAndReplace { location, .. } => {
-                if let Some(local) = find_local(location) {
+                if let Some(local) = location.base_direct().and_then(PlaceBase::local) {
                     trans.gen(local);
                 }
             }
@@ -92,28 +92,12 @@ struct BorrowedLocalsVisitor<'gk> {
     trans: &'gk mut GenKillSet<Local>,
 }
 
-fn find_local(place: &Place<'_>) -> Option<Local> {
-    place.iterate(|place_base, place_projection| {
-        for proj in place_projection {
-            if proj.elem == ProjectionElem::Deref {
-                return None;
-            }
-        }
-
-        if let PlaceBase::Local(local) = place_base {
-            Some(*local)
-        } else {
-            None
-        }
-    })
-}
-
 impl<'tcx> Visitor<'tcx> for BorrowedLocalsVisitor<'_> {
     fn visit_rvalue(&mut self,
                     rvalue: &Rvalue<'tcx>,
                     location: Location) {
         if let Rvalue::Ref(_, _, ref place) = *rvalue {
-            if let Some(local) = find_local(place) {
+            if let Some(local) = place.base_direct().and_then(PlaceBase::local) {
                 self.trans.gen(local);
             }
         }