From b7c04d152b92f137cd452ea45dcb9d2568953c86 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Wed, 14 Nov 2012 19:28:43 -0800
Subject: [PATCH] Inherit mutability through fixed-length vectors.

Fixes #3226.  No review (one line bug fix).
---
 src/librustc/middle/mem_categorization.rs        |  3 ++-
 ...tability-inherits-through-fixed-length-vec.rs | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 src/test/run-pass/mutability-inherits-through-fixed-length-vec.rs

diff --git a/src/librustc/middle/mem_categorization.rs b/src/librustc/middle/mem_categorization.rs
index a43dc0747de..2060eba7da6 100644
--- a/src/librustc/middle/mem_categorization.rs
+++ b/src/librustc/middle/mem_categorization.rs
@@ -797,7 +797,8 @@ impl &mem_categorization_ctxt {
 
           deref_comp(_) => {
             // fixed-length vectors have no deref
-            comp(expr, base_cmt, base_cmt.ty, mt.mutbl, mt.ty)
+            let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl);
+            comp(expr, base_cmt, base_cmt.ty, m, mt.ty)
           }
         };
 
diff --git a/src/test/run-pass/mutability-inherits-through-fixed-length-vec.rs b/src/test/run-pass/mutability-inherits-through-fixed-length-vec.rs
new file mode 100644
index 00000000000..c51c4b20457
--- /dev/null
+++ b/src/test/run-pass/mutability-inherits-through-fixed-length-vec.rs
@@ -0,0 +1,16 @@
+fn test1() {
+    let mut ints = [0, ..32];
+    ints[0] += 1;
+    assert ints[0] == 1;
+}
+
+fn test2() {
+    let mut ints = [0, ..32];
+    for vec::each_mut(ints) |i| { *i += 22; }
+    for ints.each |i| { assert *i == 22; }
+}
+
+fn main() {
+    test1();
+    test2();
+}