From df1c55a47434b2d79dea43673a3a97b9e955ce82 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 20 Nov 2020 11:50:15 +0100
Subject: [PATCH] add function to iterate through all sub-places, and add
 PlaceRef::ty

---
 compiler/rustc_middle/src/mir/mod.rs | 9 +++++++++
 compiler/rustc_middle/src/mir/tcx.rs | 9 +++++++++
 2 files changed, 18 insertions(+)

diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 9289d4708de1..4a7d4dab5079 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -1741,6 +1741,15 @@ impl<'tcx> Place<'tcx> {
     pub fn as_ref(&self) -> PlaceRef<'tcx> {
         PlaceRef { local: self.local, projection: &self.projection }
     }
+
+    /// Iterate over the projections in evaluation order, i.e., the first element is the base with
+    /// its projection and then subsequently more projections are added.
+    pub fn iter_projections(self) -> impl Iterator<Item=(PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
+        self.projection.iter().enumerate().map(move |(i, proj)| {
+            let base = PlaceRef { local: self.local, projection: &self.projection[..i] };
+            (base, proj)
+        })
+    }
 }
 
 impl From<Local> for Place<'_> {
diff --git a/compiler/rustc_middle/src/mir/tcx.rs b/compiler/rustc_middle/src/mir/tcx.rs
index f0bfdae261c6..1b2c1076a688 100644
--- a/compiler/rustc_middle/src/mir/tcx.rs
+++ b/compiler/rustc_middle/src/mir/tcx.rs
@@ -136,6 +136,15 @@ impl<'tcx> Place<'tcx> {
     }
 }
 
+impl<'tcx> PlaceRef<'tcx> {
+    pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> PlaceTy<'tcx>
+    where
+        D: HasLocalDecls<'tcx>,
+    {
+        Place::ty_from(self.local, &self.projection, local_decls, tcx)
+    }
+}
+
 pub enum RvalueInitializationState {
     Shallow,
     Deep,