auto merge of #16883 : jakub-/rust/issue-16648, r=pcwalton

They were only correct in the simplest case. Some of the optimisations
are certainly possible but should be introduced carefully and only
when the whole pattern codegen infrastructure is in a better shape.

Fixes #16648.

src/test/run-pass/issue-16648.rs

@@ -0,0 +1,20 @@
+// 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 main() {
+    let x: (int, &[int]) = (2i, &[1i, 2i]);
+    assert_eq!(match x {
+        (0, [_, _]) => 0,
+        (1, _) => 1,
+        (2, [_, _]) => 2,
+        (2, _) => 3,
+        _ => 4
+    }, 2i);
+}