Convert Place's projection to a boxed slice

[rust.git] / src / librustc_mir / transform / add_retag.rs

diff --git a/src/librustc_mir/transform/add_retag.rs b/src/librustc_mir/transform/add_retag.rs
index 0fd75cd57b2ac31856938a2707fa59b1274ea986..466f6060827ec1d7b15f95538157982bfbb841e0 100644 (file)
--- a/src/librustc_mir/transform/add_retag.rs
+++ b/src/librustc_mir/transform/add_retag.rs
@@ -17,12 +17,11 @@
 fn is_stable(
     place: PlaceRef<'_, '_>,
 ) -> bool {
-    if let Some(proj) = &place.projection {
-        match proj.elem {
+    place.projection.iter().all(|elem| {
+        match elem {
             // Which place this evaluates to can change with any memory write,
             // so cannot assume this to be stable.
-            ProjectionElem::Deref =>
-                false,
+            ProjectionElem::Deref => false,
             // Array indices are intersting, but MIR building generates a *fresh*
             // temporary for every array access, so the index cannot be changed as
             // a side-effect.
@@ -31,15 +30,9 @@ fn is_stable(
             ProjectionElem::Field { .. } |
             ProjectionElem::ConstantIndex { .. } |
             ProjectionElem::Subslice { .. } |
-            ProjectionElem::Downcast { .. } =>
-                is_stable(PlaceRef {
-                    base: place.base,
-                    projection: &proj.base,
-                }),
+            ProjectionElem::Downcast { .. } => true,
         }
-    } else {
-        true
-    }
+    })
 }
 
 /// Determine whether this type may be a reference (or box), and thus needs retagging.