---

yaml
---
r: 152663
b: refs/heads/try2
c: 90f7e3a
h: refs/heads/master
i:
  152661: 99acdcc
  152659: 312fd12
  152655: 9e50540
v: v3

Author: Cameron Zwarich

[refs]

@@ -5,7 +5,7 @@ refs/heads/snap-stage3: 78a7676898d9f80ab540c6df5d4c9ce35bb50463
 refs/heads/try: 519addf6277dbafccbb4159db4b710c37eaa2ec5
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
-refs/heads/try2: f99349556014f9f2cb86814477248d46931b3048
+refs/heads/try2: 90f7e3a644c9795d9a7dce87d8c6b0cf369a7503
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/try2/src/librustc/middle/borrowck/move_data.rs

@@ -25,6 +25,7 @@ use middle::dataflow::DataFlowContext;
 use middle::dataflow::BitwiseOperator;
 use middle::dataflow::DataFlowOperator;
 use euv = middle::expr_use_visitor;
+use mc = middle::mem_categorization;
 use middle::ty;
 use syntax::ast;
 use syntax::ast_util;
@@ -160,6 +161,22 @@ pub struct AssignDataFlowOperator;
 
 pub type AssignDataFlow<'a> = DataFlowContext<'a, AssignDataFlowOperator>;
 
+fn loan_path_is_precise(loan_path: &LoanPath) -> bool {
+    match *loan_path {
+        LpVar(_) => {
+            true
+        }
+        LpExtend(_, _, LpInterior(mc::InteriorElement(_))) => {
+            // Paths involving element accesses do not refer to a unique
+            // location, as there is no accurate tracking of the indices.
+            false
+        }
+        LpExtend(ref lp_base, _, _) => {
+            loan_path_is_precise(&**lp_base)
+        }
+    }
+}
+
 impl MoveData {
     pub fn new() -> MoveData {
         MoveData {
@@ -500,10 +517,17 @@ impl MoveData {
                   path: MovePathIndex,
                   kill_id: ast::NodeId,
                   dfcx_moves: &mut MoveDataFlow) {
-        self.each_applicable_move(path, |move_index| {
-            dfcx_moves.add_kill(kill_id, move_index.get());
-            true
-        });
+        // We can only perform kills for paths that refer to a unique location,
+        // since otherwise we may kill a move from one location with an
+        // assignment referring to another location.
+
+        let loan_path = self.path_loan_path(path);
+        if loan_path_is_precise(&*loan_path) {
+            self.each_applicable_move(path, |move_index| {
+                dfcx_moves.add_kill(kill_id, move_index.get());
+                true
+            });
+        }
     }
 }
 

branches/try2/src/test/compile-fail/borrowck-array-double-move.rs

@@ -0,0 +1,21 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn f() {
+    let mut a = [box 0, box 1];
+    drop(a[0]);
+    a[1] = box 2;
+    drop(a[0]); //~ ERROR use of moved value: `a[..]`
+}
+
+fn main() {
+    f();
+}
+