Fix an ICE when matching over const slices

src/test/run-pass/issue-51655.rs

@@ -0,0 +1,23 @@
+// Copyright 2018 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.
+
+#![allow(dead_code)]
+
+const PATH_DOT: &[u8] = &[b'.'];
+
+fn match_slice(element: &[u8]) {
+    match element {
+        &[] => {}
+        PATH_DOT => {}
+        _ => {}
+    }
+}
+
+fn main() {}