From a0f4914ccbb6915a150a5e57a8dab12d5afc4d8c Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Fri, 26 Apr 2019 22:18:59 +0200
Subject: [PATCH 1/3] This continue is not needed

---
 src/librustc_mir/borrow_check/mod.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs
index 1d65a018dd62d..fc1f5eb5d5a7a 100644
--- a/src/librustc_mir/borrow_check/mod.rs
+++ b/src/librustc_mir/borrow_check/mod.rs
@@ -1831,7 +1831,6 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                     }
 
                     place = base;
-                    continue;
                 }
             }
         }

From 9f7b953a7e691139ada3f390cd6f8ee9e5279642 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Thu, 2 May 2019 01:07:28 +0200
Subject: [PATCH 2/3] Remove root_local fn in favor of base_local

---
 src/librustc_mir/borrow_check/borrow_set.rs |  2 +-
 src/librustc_mir/borrow_check/place_ext.rs  | 17 +----------------
 2 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/src/librustc_mir/borrow_check/borrow_set.rs b/src/librustc_mir/borrow_check/borrow_set.rs
index 56dacf20edcb8..5ced497baa1fd 100644
--- a/src/librustc_mir/borrow_check/borrow_set.rs
+++ b/src/librustc_mir/borrow_check/borrow_set.rs
@@ -210,7 +210,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'tcx> for GatherBorrows<'a, 'gcx, 'tcx> {
 
             self.insert_as_pending_if_two_phase(location, &assigned_place, kind, idx);
 
-            if let Some(local) = borrowed_place.root_local() {
+            if let Some(local) = borrowed_place.base_local() {
                 self.local_map.entry(local).or_default().insert(idx);
             }
         }
diff --git a/src/librustc_mir/borrow_check/place_ext.rs b/src/librustc_mir/borrow_check/place_ext.rs
index 913884a821837..cf9a6165d71a2 100644
--- a/src/librustc_mir/borrow_check/place_ext.rs
+++ b/src/librustc_mir/borrow_check/place_ext.rs
@@ -1,6 +1,6 @@
 use rustc::hir;
 use rustc::mir::ProjectionElem;
-use rustc::mir::{Local, Mir, Place, PlaceBase, Mutability, Static, StaticKind};
+use rustc::mir::{Mir, Place, PlaceBase, Mutability, Static, StaticKind};
 use rustc::ty::{self, TyCtxt};
 use crate::borrow_check::borrow_set::LocalsStateAtExit;
 
@@ -16,10 +16,6 @@ crate trait PlaceExt<'tcx> {
         mir: &Mir<'tcx>,
         locals_state_at_exit: &LocalsStateAtExit,
         ) -> bool;
-
-    /// If this is a place like `x.f.g`, returns the local
-    /// `x`. Returns `None` if this is based in a static.
-    fn root_local(&self) -> Option<Local>;
 }
 
 impl<'tcx> PlaceExt<'tcx> for Place<'tcx> {
@@ -82,15 +78,4 @@ impl<'tcx> PlaceExt<'tcx> for Place<'tcx> {
             },
         }
     }
-
-    fn root_local(&self) -> Option<Local> {
-        let mut p = self;
-        loop {
-            match p {
-                Place::Projection(pi) => p = &pi.base,
-                Place::Base(PlaceBase::Static(_)) => return None,
-                Place::Base(PlaceBase::Local(l)) => return Some(*l),
-            }
-        }
-    }
 }

From 49f01413748f536f49b3d14845dbe5dd717b6b84 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Thu, 2 May 2019 01:07:44 +0200
Subject: [PATCH 3/3] Implement base_local iteratively

---
 src/librustc/mir/mod.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index 0dc23f5ce47e5..f23ff47b5ff66 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -2055,10 +2055,13 @@ impl<'tcx> Place<'tcx> {
 
     /// Finds the innermost `Local` from this `Place`.
     pub fn base_local(&self) -> Option<Local> {
-        match self {
-            Place::Base(PlaceBase::Local(local)) => Some(*local),
-            Place::Projection(box Projection { base, elem: _ }) => base.base_local(),
-            Place::Base(PlaceBase::Static(..)) => None,
+        let mut place = self;
+        loop {
+            match place {
+                Place::Projection(proj) => place = &proj.base,
+                Place::Base(PlaceBase::Static(_)) => return None,
+                Place::Base(PlaceBase::Local(local)) => return Some(*local),
+            }
         }
     }