Fix a #14731 regression in missing_constructor() for vector patterns

Fixes #15080.

src/test/run-pass/issue-15080.rs

@@ -0,0 +1,30 @@
+// 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 mut x = &[1, 2, 3, 4];
+
+    let mut result = vec!();
+    loop {
+        x = match x {
+            [1, n, 3, ..rest] => {
+                result.push(n);
+                rest
+            }
+            [n, ..rest] => {
+                result.push(n);
+                rest
+            }
+            [] =>
+                break
+        }
+    }
+    assert!(result.as_slice() == [2, 4]);
+}

src/test/run-pass/vec-matching.rs

@@ -68,9 +68,17 @@ fn d() {
     assert_eq!(branch, 1);
 }
 
+fn e() {
+    match &[1, 2, 3] {
+        [1, 2] => (),
+        [..] => ()
+    }
+}
+
 pub fn main() {
     a();
     b();
     c();
     d();
+    e();
 }